Schematics

Alarms and security related schematics

• Proximity alarm
  
• Electronic lock
  
• Electronic door codelock (PIC16F84)
  
• Ultrasonic remote control & alarm system
  
• Wire loop alarm
  
• Door knob alarm (PDF)
  
• Water seepage alarm (PDF)
  
• Micro-power over temperature alarm (PDF)
  
• Personal silent alarm system
  
• Active IR motion detector
  
• Frost alarm
  
• Ultrasonic radar alarm
  
• Refrigerator door alarm
  
• Emergency Light & Alarm
  
• Electronic combination lock
  
• Proximity detector for humans / living creatures using eddy current detection
  
• A Basic RF Transmitter for PIR Sensors
  
• PIR motion detector
  
• Simple alarm system
  
• Home security project
  
• 5 Zone alarm circuit
  
• Miniature loop alarm
  
• Novel Buzzer
  
• Gate alarm circuit
  
• Modular Burglar Alarm
  
• Motorcycle alarm
  
• Enhanced 5 Digit Alarm Keypad
  
• Enhanced 4 Digit Alarm Keypad
  
• RF Alarm
  
• Single Zone Alarm
  
• Water Activated Alarm
  
• Water level alarm
  
• Perimeter monitor
  
• Digital combination lock
  
• Alarm control keypad
  
• Almost Ultrasonic Motion Sensor
  
• 2-input alarm
  
• Touch activated alarm system
  
• Combination Lock (PIC16F84)
  
• Low power RFID transponder (PDF)
  

• Audio power amplifier schematics

  • Two transistor audio amplifier
    
  • Personal stereo audio amp
    
  • Headphone amplifier
    
  • 1.5W Audio amplifier
    
  • Low-level audio amp
    
  • 10W amplifier
    
  • 80W amplifier
    
  • LM383 12V Amplifier
    
  • 4W amplifier
    
  • 8 watt audio amp
    
  • 20W Amplifier
    
  • 50W Amplifier
    
  • 100W RMS Amplifier
    
  • 2-Channel Power Amplifier
    
  • 25W MOSFET audio amplifier
    
  • 50W audio amplifier using ICL8063
    
  • Amplified ear for surveillance
    
  • 20dB VHF Amplifier
    
  • 30 watt FM linear amplifier
    
  • Linear FM 50 watt amplifier with BLY90
    
  • 60W RF linear amplifier using IRF840
    
  • Push-Pull Class A Amp using type 5687 dual triodes
    
  • Push-Pull Class A 2A3 Stereo Amp
    
  • Single Ended Class A2 SV811-10 Stereo Amp
    
  • Compact 50W Integrated Amplifier with Meier Headphone Section
    
  • Audio amplifier output relay delay
    
  • Spatial Distortion Reduction Headphone Amp
    
  • HeadBanger Headphone Amp
    
  • 2W Amplifier
    
  • TDA2030 8 Watt amplifier
    
  • Headphone monitor amp
    
  • 50W audio power amplifier
    
  • Bi-Directional 2.4 GHz One Watt Amplifier
    
  • Bi-Directional 900Mhz One Watt Amplifier
    
  • 20 Watt GaAaFET Power on 2.3 GHz
    
  • 1 Watt 2.3 GHz RF Amplifier Using a MRF2001
    
  • 2.3 GHz Power Amplifiers
    
  • 2304 and 3456 MHz Power Amplifiers
    
  • High quality exponential VCA
    
  • 16 Watt amplifier
    
  • 8 Watt amplifier
    
  • 20 Watt Class-A Power Amplifier
    
  • El-Cheapo - A Really Simple Power Amplifier
    
  • Single Chip 50 Watt / 8 Ohm Power Amplifier
    
  • Hi-Fi Headphone Amplifier
    
  • 100W Guitar Amplifier
    
  • Death of Zen (DoZ) - A New Class-A Power Amp
    
  • Soft-Start Circuit For Power Amps
    
  • Thermo-Fan To Keep Your Amp Cool
    
  • Audio Amp Output Power Limiter
    
  • 55W (Originally 75W) Power Amplifier
    
  • 300W Subwoofer Power Amplifier
    
  • 20 Watt / Channel Stereo Power Amplifier
    
  • Mini bench amplifier (LM386)
    
  • Small bench amplifier ideal for testing audio stages in circuits
    
  • 12 Watt Valve Guitar Amp
    
  • Five Tube Stereo Amplifier
    

  Audio preamp circuits

  • Microphone amplifier
    
  • RIAA phono amplifier
    
  • Low impedance microphone amplifier
    
  • High quality audio preamplifier (OPA2134)
    
  • Masthead preamp
    
  • Preamplifier for microphone or guitar use
    
  • Simple microphone preamplifier
    
  • Tube microphone preamp
    
  • Simple Stereo Electret Microphone Preamplifier
    
  • Simple Stereo Electret Microphone Preamplifier
    
  • Phono Preamp
    
  • Simple microphone preamplifier
    
  • ECM Mic preamp
    
  • Hi Fi preamp
    
  • Balanced microphone preamp
    
  • Electret mic amplifier
    
  • Audio preamplifier
    
  • Vacuum Tube Microphone Preamp
    
  • FET Preamp Cable
    
  • Altec 1564A Preamp Power Supply
    
  • Neumann U67 microphone preamp power supply
    
  • Audio preamp
    
  • Telefunken/Siemens/Maihak/TAB V72 microphone preamp schematic
    
  • Altec 428B Microphone Preamplifier schematic
    
  • API 321 mic preamp schematic
    
  • RCA BA-1A two-stage preamp schematic
    
  • RCA BA-21A preamplifier schematic
    
  • RCA BA-31A preamplifier schematic
    

  Automative, car and motorcycle schematics

  • Electronic auto stethoscope
    
  • Turn signal alarm
    
  • Motorcycle turn-signal system
    
  • Cigarette lighter 9V adaptor
    
  • Adaptive Windscreen Wiper Control
    
  • Car OBDII diagnostic interface cable schematic pinout
    
  • Car OBD II J1850 PWM, J1850 VPW, ISO-9141 cables schematic pinout
    
  • Grand Cherokee Off-Highway Lights
    
  • Engine control unit schematics
    
  • Portable CD Player Adapter For Car
    
  • Car battery charger
    
  • Wireless Auto Tachometer
    
  • Headlight reminder
    
  • Breath Alcohol Tester controlling a car ignition system
    
  • Simple car battery charger
    
  • Flashing / pulsing third brake like for cars
    
  • Headlight flasher
    
  • Speed alert - wireless portable unit
    
  • Parking aid senses distance to rear of vehicle
    
  • Automatic headlight brightness switch
    
  • Car battery charger circuit
    
  • Electronic car ignition circuit
    
  • Car battery voltage tester using LM3914
    
  • Synchronized multi-spark module (SMSM) for Electronic Ignition Devices (EID)
    
  • Economy radar detector
    
  • Headlight timer
    
  • Parking sonar
    
  • Fuel injector pulse width monitor
    
  • BMW R Series Motorcycle Regulator Schematic
    
  • 80188XL Engine Tachometer
    
  • Simple Car Preamplifier and Artificial Earth
    
  • Breakdown safety beacon
    
  • FCD (Fuel Cut Defencer)
    
  • Interface between GM's 5 Volt 8192 baud ALDL data stream and a PC serial port
    
  • 5301 wideband fuel mixture display
    
  • Wide Band Fuel Mixture Display
    
  • 3rd brake light
    
  • 12V to 9V car coverter
    
  • Car Nicad charger
    
  • Combination lock for car liftgate
    

  Data acquisition (DAQ) and data logging schematics

  • Air flow detector
    
  • Air flow detector
    
  • Strain gauge sensor
    
  • Digital Water Wave/Tide/Level Meter (PIC16F876)
    
  • 8 Photo-Detector Circuit Board
    
  • Self made data-logger V2.5 (second edition)
    
  • Magnetometer
    
  • Analog input section based on AD9220
    
  • uModem 4+4/8 channel A/D board
    
  • ADXL202 accelerometer to CV output
    
  • Universal flight controllers / datalogger
    
  • Rain detector
    
  • Home Brew Compass Sensor
    
  • Using 555 Timer as an A/D converter
    
  • ADC0804LCN 8-bit A/D converter
    
  • Web-based thermometer project
    
  • Honey Bee counter (PDF)
    
  • Capacitance type liquid level measurement (PDF)
    
  • Thermostat node schematic
    
  • Digital PC Oscilloscope
    
  • Ultrasonic Range & Imager
    
  • Precision Digital Altimeter
    
  • Remote digital thermometer sends data over AC power line
    
  • 4-channel data telemetry system
    
  • Voltage follower with 1G ohm input resistance
    
  • Digital compass schematic
    
  • Temperature datalogger
    
  • Serial Port A/D-converter
    
  • Centronics port D/A converters and low-pass filter
    
  • LCD Thermometer
    
  • Wireless Liquid Level Sensing for Restaurant Applications
    
  • Accelerometer Schematic
    
  • Pressure Sensor-Based Altimeter Circuit
    
  • Ultrasonic range finder circuit
    
  • 1-wire barometer
    
  • Water-level sensor
    
  • Addressable ADC
    
  • Electronic altimeter using PIC16F877
    
  • Wireless weater station
    

  Filter schematics

  • Galaxy Noise Filter
    
  • Low-pass active filter
    
  • Filter Circuit for the Earthworm Seismic Data Acquisition System
    
  • 45 to 90Hz hum filter
    
  • Active 2nd Order Filters
    
  • RC Notch Filter (Twin T)
    
  • 'A' Weighting Filter For Audio Measurements
    
  • Multiple Feedback Bandpass Filter
    
  • CW filters
    
  • Self-tune filter
    
  • SSB AF filter
    
  • CW Filters
    
  • Self-tuning CW filter
    
  • SSB AF filter
    
  • Helical Resonator Notch Filter
    
  • 3KHz low-pass filter plus audio amp (PDF)
    
  • Active bandpass filters
    
  • Bandpass filters
    
  • Butterworth filters
    
  • Narrow band audio bandpass filter
    
  • Chebyshev Bandpass Filter
    
  • Bandpass filters
    
  • Chebyshev / Butterworth filters
    
  • Biquad Active Bandpass Filter Schematic
    
  • "A" Weighting Filter For Audio Measurements
    
  • Multiple Feedback Bandpass Filter
    
  • Digital signal processor (DSP) for radio communications
    
  • 29.85 MHZ bandpass filter schematic
    
  • 29.85 MHZ notch filter schematic
    
  • Variable notch filter with both high and low pass filters
    
  • LC filter design
    

  Games and fun stuff (electronic schematics)

  • Visor cradle serial interface
    
  • Electronic coin tosser
    
  • Electronic craps game
    
  • First response monitor
    
  • VCR ping pong game
    
  • Video ping pong game
    
  • MBC5/CPLD for the GameBoy
    
  • GameBoy Camera Parallel Port Interface
    
  • PSX controler to PC MIDI converter
    
  • Dreamcast PC serial adapter
    
  • GameBoy Cart Programmer
    
  • 32 Kb x 8 emulator for the GameBoy
    
  • Project: NES to Atari 2600 controller interface
    
  • Battery Meter for Pinball Machines
    
  • SRX1 (Stephane's Robotic eXperiment 1)
    
  • Pine Racecar Victory Judge
    
  • Interfacing Sony control stick to Empeg
    
  • Electronic Nicad glow plug driver
    
  • Multi-User Jeopardy Game (Fastest Finger First)
    
  • Quiz show indicator
    
  • Dreamcast interface
    
  • Flashing heart
    
  • Phoenix programmer
    
  • Funcard programmer
    
  • Bingo!!! (on your tv)
    
  • Slot car TV cronograph
    
  • Furby reverse-engineered circuit
    
  • Sanyo 20EZ monitor Arcade Game (300k ZIP)
    
  • Burger Time Arcade Game (500k ZIP)
    
  • Dig Dug Arcade Game (800k ZIP)
    
  • Frogger Arcade Game (500k ZIP)
    
  • Galaga Arcade Game (542k ZIP)
    
  • Gyrus Arcade Game (800k ZIP)
    
  • Junior Pacman Arcade Game (400k)
    
  • Ladybug Arcade Game (335k ZIP)
    
  • Mappy Arcade Game (470k ZIP)
    
  • Moon Cresta Arcade Game (300k ZIP)
    
  • Mr.Do Arcade Game (554k ZIP)
    
  • PacLand Arcade Game (316k ZIP)
    
  • Pengo Arcade Game (313k ZIP)
    
  • Q*Bert Arcade Game (600k ZIP)
    
  • Qix Arcade Game (476k ZIP)
    
  • Scramble Arcade Game (600k ZIP)
    
  • Time Pilot'84 Arcade Game (870k ZIP)
    
  • Xevious Arcade Game (450k ZIP)
    
  • Magic Wand Conjuring Trick
    
  • Quiz game circuit
    
  • E.S.P. Conjuring Trick
    
  • Space invaders game using PIC microcontroller
    
  • DIT shutterglasses controller
    
  • Tic-tac-toe game using PIC16F628
    
  • Hangman game
    
  • LED dice with slow down tumbling action
    
  • LED Zeppelin game of skill and patience
    
  • Lotto number selector helps you win a fortune
    
  • Simon Says memory game using a PIC16F84A or PIC16F628 microcontroller
    
  • Spin the device educational project based on PIC12F629 microcontroller
    
  • Tic Tac Toe game based on Microchip PIC16F628 microcontroller
    
  • Game Show Timers
    
  • Archery timer
    
  • Coin tosser
    
  • PIC micro Tetris game
    
  • Magic lamp, IR remote control jammer and other fun circuits (PDF)
    
  • Lego Mindstorms Double Rotation Sensor
    

  Infrared based schematics

  • IR detector
    
  • Infrared body heat detector
    
  • Stereo IR audio receiver
    
  • General purpose IR receiver
    
  • Wireless IR headphone transmitter
    
  • Wireless IR headphone receiver
    
  • Infrared Receiver Module Schematics
    
  • Infrared transmitter for locomotives
    
  • Infrared gate for door
    
  • Infrared circuits for remote control
    
  • Serial port controller infrared transmitter (PIC16F628)
    
  • Digibox interface
    
  • IR remote control
    
  • 40KHz light receiver (PDF)
    
  • 40KHz TV-VCR repeater (PDF)
    
  • Micro based PIR to IR remote converter
    
  • IR-related ASCII Schematics V1.00
    
  • Infrared remote transponder
    
  • Build an Infrared night scope
    
  • Decoding IR Remote Controls
    
  • IR detector
    
  • PC IR Remote Control Hardware
    
  • PC IR Remote Control
    
  • An Ambient-Light-Ignoring Infrared Active Motion Detector
    
  • Simple on-off IR photoswitch without use of comparators
    
  • Infrared gate (door entry alarm)
    
  • Infrared switch using any infrared remote control
    
  • Improved infrared receiver for PC with status LED
    
  • Infrared link for 10-BASE-T / 100-BASE-T PC network card
    
  • iRDA transceiver to extend IR port range up to 15 meters
    
  • Infrared level detector for liquid level detection and proximity detection
    
  • IR remote control tester
    
  • Infrared Transmitter and Receiver schematic diagrams
    
  • Pyroelectric Infrared Sensor
    
  • Minimal Infrared transmitter for PC
    
  • Simple IR transmitter circuit
    
  • Simple infra-red detector
    
  • Infra Red Switch
    
  • IR remote control extender
    
  • IR Remote Control Extender Circuit (Mark 2)
    
  • IR Remote Control Extender Circuit (Mark 3)
    
  • IR Link
    
  • IR remote control tester
    
  • 40khz IR Tester
    
  • 555 timer 40khz IR Oscillator
    
  • IR detector / emitter
    
  • Fire-Stick infrared remote control
    
  • Simple infrared remote control
    
  • Infrared / Ultrasonic beacon
    
  • Implementing Infrared Object Detection
    
  • Computerized Infrared Remote
    

  Laser related power supplies and data transmission

  • Light beam receiver for laser pistols
    
  • 12V supply for He-Ne laser
    
  • Laser diode transmitter
    
  • Low Cost Scanning Laser Rangefinder (PDF)
    
  • Sniper tag laser beam detector
    
  • Laser high-voltage power supply
    
  • Laser power supply
    
  • Laser transmitter/receiver
    
  • Time of flight imagine (PDF)
    
  • Laser harp
    
  • Laser light output intensity meter
    
  • 20MHz VCSEL 3mW laser test circuit (PDF)
    
  • 10MHz to 20MHz laser light detector (PDF)
    
  • Micro-power 40KHz burst laser diode driver (PDF)
    
  • 40KHz laser burst detector (PDF)
    
  • Modulated laser diode tester (PDF)
    
  • Laser range finder and reflectivity meter for the MARS-96 international space project (PDF)
    
  • Ar/Kr Ion Laser Power Supply
    
  • Laser diode power supply circuits
    
  • RS-232 Laser Transceiver
    
  • RS-232 laser transceiver
    
  • Digital radar speedometer - laser reflexion using discrete logic
    
  • HeNe laser power supply
    
  • OPT201 Laser receiver
    
  • OPT301 Laser receiver
    
  • Laser transmitter schematics
    
  • Rangefinder with Fast Multiple Range Capability
    
  • Diode Laser Power Supplies
    
  • Complete Helium Neon Laser Power Supply Schematics
    
  • Home built 100kW nitrogen laser
    
  • RS-232 Laser Transceiver
    
  • Experimental laser data link
    
  • Laser Target Finder Sensor
    
  • Ar/Kr Ion Laser Power Supply Design
    
  • Micro-Laser range finder
    
  • Simple laser communicator
    
  • Real-time Laser Range Finding Vision System
    

  LED related schematics

  • Single and Two Cell White LED Drivers Without Inductors
    
  • Big 7-segment LED display board with SPI interface
    
  • LED Flasher
    
  • LED pulser with audible output
    
  • IR Illuminator
    
  • Flashing Christmas LED display
    
  • ICL7660 LED flasher
    
  • LM3909 replacement using discrete components
    
  • 10, 8 And 6 Step LED Circuits (CD4017)
    
  • Colour Shifting For Bi-Colour LED's
    
  • Current Regulators For Light Emitting Diodes
    
  • Incandescent LED Circuit
    
  • Various LM555 LED Blinker Circuits
    
  • Color fade
    
  • 1.5 Volt LED Flashers
    
  • AC Line Powered LEDs
    
  • Astable Multivibrator
    
  • 9 Second Digital Readout Timer
    
  • 9 Second LED Relay Timer
    
  • 16 Stage Bi-Directional LED Sequencer, other sequencer and flaser circuits
    
  • 10 Stage LED Sequencer
    
  • 28 LED Clock Timer
    
  • Fading Red Eyes
    
  • Two Transistor LED Flasher
    
  • 16 Stage Bi-Directional LED Sequencer
    
  • Expandable 16 Stage LED Sequencer
    
  • LED Photo Sensor Circuit
    
  • LED chaser
    
  • 7 Segment LED Counter
    
  • 7 by 10 LED Moving Sign ( 27C512 EPROM)
    
  • 1.5V LED flasher B (PDF)
    
  • Low current LED flasher (PDF)
    
  • 1.5V LED flasher A (PDF)
    
  • Flashing LED advertising badge (PDF)
    
  • Flashing LED advertising badge (PDF)
    
  • Pulsed LED test circuit (PDF)
    
  • Low battery voltage flasher (PDF)
    
  • Adjustable flashing LED
    
  • Knight rider scanning LED lights
    
  • 3V LED chaser using 4017
    
  • 6V ultra-bright LED chaser using 74HC4017
    
  • Led display digital Voltmeter
    
  • PWM white LED drivers
    
  • Heart of LEDs
    
  • Christmas Star
    
  • Christmas tree
    
  • LED Counter
    
  • PIC16F84 LED chaser
    
  • PIC16F84 LED signboard
    
  • PIC16F84 LED signboard 2
    
  • White LED circuits
    
  • Assorted LED circuits
    
  • 13 Color LED Rainbow
    
  • Seven Component Regulated LED Lamp
    
  • High Efficiency 12V White LED Driver
    
  • LED Mood Light
    
  • LED Audio VU Meter
    
  • Robot Beacon rotating light using PIC12C508
    
  • 5x7 Display
    
  • Various LED flashers
    
  • Kitt car scanning LED sequencer
    
  • Robot beacon light display for mounting on top of a robot
    
  • Sky writer - displays 'in air' messages and features inertia switch
    
  • LM3909 LED flasher
    
  • Animated LED signboard (PIC16C84)
    
  • Picxie 2 - 8x8 Animated LED Signboard
    

  Lighting and ligh controller schematics

  • Garden light switch
    
  • DMX lighting and special effects
    
  • 1200 Watt Lamp Dimmer Circuit using Q4015LT combination Diac
    
  • Diode Type Constant Lighting Circuits
    
  • Microcontroller Multichannel Light Dimmer
    
  • Varying Brightness AC Lamp
    
  • 12 Volt Lamp Dimmer
    
  • 120VAC Lamp Chaser Using Solid State Relays
    
  • Flashing Neons (NE-51 / NE-2)
    
  • Sequencing Neons (NE-51 / NE-2)
    
  • Touch Activated Lamp
    
  • TRIAC light dimmer
    
  • 12VDC Fluorescent Lamp Driver
    
  • Strobe light
    
  • Adjustable Strobe Light
    
  • RHINO8 EL Sequencer
    
  • 5W Fluorescent light intensity modulator (PDF)
    
  • 1W Fluorescent lamp night light (PDF)
    
  • 6 Channel Auto Reverse Sequential Disco Running Lights
    
  • Low-voltage light dimmer
    
  • Light chaser
    
  • Digi Pack DMX 512 lighting controller
    
  • DMX PC keyboard interface
    
  • 4-channel dimmer rack
    
  • PIC16F873 light controller
    
  • Digitally Addressable DALI Dimming Ballast (PDF)
    
  • Disco light controller
    
  • Neon desklamp
    
  • Electronic night light
    
  • Neon lamp dimmer
    
  • LED Mood Light
    
  • LX-800 Lighting system
    
  • Xenon Strobe Light
    
  • 12V florescent light inverter
    
  • 3 Xenone flashing circuits found in flash for disposable cameras
    
  • Lamp flasher/dimmer
    
  • Christmas lights tester
    

  Medical and health related schematics

  • Heart Rate and EKG Monitor using the MSP430FG439 (PDF)
    
  • Snore alarm electronic device
    
  • Heartbeat transducer
    
  • ECG Amplifier
    
  • EKG/EEG circuit
    
  • Wireless Electrocardiogram Monitor
    
  • Heart Rate Monitor (HRM) Receiver Circuit
    
  • Simple lie detector
    
  • ECG Measurement and Analysis
    
  • Cardiac monitor
    
  • Digital pedometer circuit
    
  • Muscular Bio-Stimulator
    
  • Sleeping aid based on electromagnetic-field radiation
    
  • Salt taster - detects the amount of salt contained in liquid foods
    
  • Electronic Stethoscope
    
  • Optical Heart Rate Monitor
    
  • Model 2030 XRAY monitor instruction manual including schematics (PDF)
    
  • Galvanic Skin Response (GSR) Schematic
    
  • Brain-Wave Machine
    
  • Lie detector
    
  • Simple lie detector
    
  • ECG Heart Monitor
    
  • Portable blood pressure monitor
    
  • Heart rate sensor
    
  • The ESP SIM (Sound Impairment Monitor)
    
  • Stress meter educational project using PIC12F629 microcontroller
    
  • Respiration system
    

  Microcontroller based schematics

  • PIC based packet radio encoder (PDF)
    
  • RS485-Version of the SAB80C535-Microcontrollerboard
    
  • PC IR receiver based on PIC16F84
    
  • Record and play fast 1-bit sound on a PIC micro
    
  • AT89C2051/4051scanning 7-segment display and keypad
    
  • AT89C2051/4051 Driving dot LED
    
  • AT89C2051/4051stepper motor interface
    
  • AT89C2051/4051connecting dumb terminal
    
  • Motorola 68K SBC (single board computer)
    
  • 8051 SBC (single board computer)
    
  • Simple RS232C Level Converter using Transistors
    
  • Motorola 68HC11 evaluation board
    
  • C-52 EVB Robot Controller
    
  • Mains clock controller using AT89C2051
    
  • AT89C2051/4051 Easy-Downloader
    
  • AT89C51/52/55 Easy-Downloader
    
  • PIC16F84 programmer
    
  • PIC16F84 miniature real-time controller
    
  • Isolated RS232 for PIC16F84
    
  • PIC16F84 debugging terminal
    
  • MiniLOGGER V1.0
    
  • Analog datalogger based on T89C51RD2
    
  • Atmel 89C Series Flash Microcontroller Programmer
    
  • Atmel 89C2051 prototype board
    
  • AT89C2051 real-time controller
    
  • PIC12C508 Night-light saver
    
  • AT89C2051 Night light saver
    
  • Atmel 8051 Flash Based-Microcontroller Programmer
    
  • AT89C2051 Digital thermometer and clock
    
  • 4-Channel Timer using Atmel 89C4051 and MAX7219 display driver
    
  • PIC16F84 CW decoder (PDF)
    
  • Several Atmel AVR programmer circuits
    
  • 12C508 Smart Lock
    
  • Basic Stamp based altimeter
    
  • Interfacing EEPROM to a Basic Stamp
    
  • Homebrew Basic Stamp project
    
  • Interfacing the MAX186 8 Channel ADC to the BSII
    
  • Interfacing the MAX187 ADC to the BSII to measure voltages
    
  • RF remote control based on Basic Stamp
    
  • 80C31 stepper motor controller
    
  • Build a PIC controlled DDS VFO, 0 to 6 MHz
    
  • PIC controlled DDS VFO, 0 to 6 MHz
    
  • Basic Stamp Lightning Activity Monitor
    
  • Parallel AVR programmer
    
  • PIC16F84 line following robot
    
  • PIC16C505 IR / wireless remote control
    
  • Automatic door opener with PIC12C508
    
  • RS485-like multi-drop bus with half duplex serial protocol
    
  • 50 MHz frequency counter, voltage meter & SWR/PWR indicator
    
  • Programmer PIC16F84,12C50x and EEPROM 24Cxx
    
  • RDS Encoder - digital part
    
  • PIC programmer for serial port
    
  • Fully functional PS/2 mouse based on the PIC16F84
    
  • PIC 18 programmer (PIC18F458, PIC18F452, PIC18C252, PIC16C745, PIC18F6620, PIC18F6720)
    
  • Serial-based PIC16F84 Programmer For Windows 95/98/NT/2000/ME/XP
    
  • PIXpand
    
  • PIC16F877 to IDE interface
    
  • 90S2313 AVR Robot Board
    
  • POCSAG encoder/decoder
    
  • Rotating Sprocket Wheel Generator (PIC16F84)
    
  • Minimal PIC18 board (PDF)
    
  • Talking PIC - based on SP0256
    
  • Sharp GP2D02 Interface to PIC Microcontroller
    
  • Sharp GP2D05 Interface to PIC Microcontroller Sharp GP2D05 Interface to PIC Microcontroller
    
  • Serial to parallel converter using the AT89C2051
    
  • AT89C2051 serial COMs to LED driver
    
  • PIC16F877 Programmer And Development System
    
  • DS1820 Arbiter V2.00 Schematic
    
  • Microchip PIC ICSP implementation
    
  • 101 AT Keyboard to ASCII Decoder using 68HC705J1A MCU
    
  • LCD Serial Terminal
    
  • Propellor clock (PIC16F84)
    
  • A Scenix (and PIC) Programmer
    
  • MMC to PIC16F876 circuit diagram
    
  • 8088 maximum mode SBC
    
  • EZ80 single board computer schematic (Z80)
    
  • 8051 Development System Circuit Board
    
  • Long-period watchdog timer
    
  • PIC Web Server Schematic
    
  • Generate video signals in real-time using a PIC16F84
    
  • PIC ICD
    
  • Tachometer Measures Very Low Frequencies (PIC16F872)
    
  • Smart card programmer
    
  • Jupiter card programemr
    
  • Tutorial board for PIC16F84A microcontroller
    
  • PIC Project #1 - RS232 to I2C Interface
    
  • Galvanic decoupling of I2C bus
    
  • Programmer PIC16F84,12C50x and EEPROM 24Cxx
    
  • Dual PIC16C84 prototype board
    
  • Graphic LCD interface
    
  • Interfacing a 4X4 keypad to a BS2 using a 74922 encoder chip
    
  • FSK modem with PIC16C84
    
  • Talking YODA project (PIC16C84)
    
  • PIC16F84/PIC16F87x-In-System-Programmer
    
  • Microcontroller interface for 5KW microwave oven
    
  • Using an I2C Serial EEPROM with a Basic Stamp 2
    
  • PIC16F84 Based Morse Code Reader
    
  • AVR-Based Serial Port IR Receiver
    
  • Interfacing piezo elements to a microcontroller
    
  • Victoria TAFE programmer (based on AT89C2051)
    
  • JDM programmer
    
  • PIC micro programmer
    
  • Speech recognition using HM2007
    
  • PIC microcontroller servo motor interface
    
  • PIC micro multiple servo motor interface
    
  • PIC16F84 countdown timer
    
  • PIC16F873 ultrasonic range meter
    
  • PIC16F873 Digital clock
    
  • PIC16F873 remote display
    
  • PIC16F84 stepper motor controller
    
  • Way small web server
    
  • PICADC - a free, PIC based "intelligent" A/D converter
    
  • PIC-Programmer 2
    
  • Connecting PIC12C508 8 to 93AA46 serial eprom
    
  • KD7LMO Micro Beacon (PIC18F252)
    
  • GPS LCD Display Project
    
  • PIC16F84 LED chaser
    
  • PIC micro LED projects
    
  • PS/2 keyboard keystroke logger based on Atmel 89C2051
    
  • Electronic distance meter based on Motorola 68HC908QY4
    
  • Fan timer based on Motorola 68HC908QT2
    
  • Atmel AVR and 8051 series ISP programmer
    
  • AT89C2051 line-follower robot
    
  • Night light saver (PIC12C508)
    
  • USB and GLCD expansion board for 8051 SBC
    
  • Microcontroller sensor and actuator interfaces
    
  • Giant money counter (PIC16F876)
    
  • PIC12C509 logic gate replacement for nitrogen filler
    
  • PIC demo board
    
  • PIC12C509 Gym Timer
    
  • PIC LCD and Keypad driver
    
  • PIC12C508 Phase Controller for 2kW heater
    
  • PIC16F84 TRIAC / IGBT brightness phase controller
    
  • PIC16F84 pulse monitor with date/time output (ZIP)
    
  • Programmer for the 68HC705C8 MicroController
    
  • 27c801 EPROM Programmer Project
    
  • LCD to PIC16C54 schematic
    
  • 68HC11 based RDS decoder
    
  • Acceleration monitor using ADXL202 and AVR
    
  • 40+ MHz 5-digit frequency counter with an AVR 2313
    
  • Interfacing DRAM to AT90S8515
    
  • Temperature monitor/controller: AVR 2313 / DS1621
    
  • PIC micro to ISA bus interface
    
  • Microchip PIC ICD (in-circuit debugger)
    
  • Tony Nixons Pocket Programmer (PIC)
    
  • PicoWeb V5.1 (AT90S8515) tiny web server
    
  • Atmel 89C2051 In-Circuit Programmer Schematic
    
  • 8051 Development System Circuit Board
    
  • 8051 Development System Circuit Board
    
  • 8051 Development System Circuit Board
    
  • Microprocessor using Xilinx FPGA
    
  • Temperature controlled based on AT89CX051
    
  • I2C LCD interface
    
  • AFSK 1200 Modem based on PIC16C620
    
  • PicCon - Hidden Radio Transmitter Controller
    
  • PIC16F84 tone generator with source code
    
  • PIC16F84 tone generator
    
  • PIC16F84 tone generator (6-Bit)
    
  • AVR Beacon Super Keyer
    
  • AVR Frequency Counter
    
  • AVR Digital Voltmeter
    
  • AVR Signal Generator
    
  • Designing a 4-Channel A/D (ADC) converter with the PIC12C671
    
  • Ser-Key 10-Key Serial Keypad Encoder
    
  • 2-wire LCD interface using PIC16CF84
    
  • PIC16F84 Serial I/O-expander with PicBasic
    
  • Camera remote control system using Basic Stamp
    
  • Low cost Atmel in-system programmer
    
  • Ultra low-cost programmer for AT90S family
    
  • Connecting AT90S2313 with LCD display 2x16 char and 4x4 keypad
    
  • Electronic safety lock based on ATtiny26
    
  • GSM SMS remote control using AVR microcontroller
    
  • 128x64 LCD Driver for AT90S2313 (ZIP file)
    
  • Connecting LED to PIC Micro I/O pins (PDF)
    
  • Microprocessor RS-232 Reset
    
  • Microprocessor RS-232 Reset
    
  • AT90S8515 experimenter board
    
  • Multi-chip programmer for PIC microcontrollers
    
  • Buffered PIC chip interface
    
  • 2-Digit Counter using the PIC12F629 chip
    
  • Multi-chip programmer for Microchip PIC microcontrollers
    
  • Multipurpose buffered PIC microcontroller development system
    
  • ScanMate audio activated recorded
    
  • PIC vacuum fluorescent display interface
    
  • PIC16F876 Datalogger
    
  • Kodak DC-20 camera interface (PIC12C509)
    
  • Kodak DC-20 camera interface (PIC16F84)
    
  • PIC ICD in-circuit debugger circuit diagram
    
  • Wisp628 ISP Microchip PIC Programmer
    
  • WLoader - PIC16F877 application loader / bootloader
    
  • Nixie clock (PIC16F876)
    
  • Zilog Z80 thermostat embedded web server
    
  • Picxie 2 - 8x8 Animated LED Signboard (PIC16F84) Picxie 2 - 8x8 Animated LED Signboard
    
  • 10 tricks for interfacing to the PIC16C508
    
  • Interfacing the PIC16C508
    
  • PIC 5x7 display
    
  • Analog to digital conversion notes
    
  • Multi-chip programmer
    

  Misc audio (also see Music, Amplifiers, Preamp)

  • Electronic siren
    
  • Two-tone siren
    
  • Underwater microphone
    
  • Code practice oscillator
    
  • Noise generator
    
  • Electronic whistle
    
  • Twin-T Audio Sine Wave Oscillator
    
  • 1.5V Audio Amplifier
    
  • Low Power Op-Amp - Audio Amp (Intercom)
    
  • 555 Tone Generator (8 Ohm Speaker)
    
  • 3 Transistor Audio Amp (50 milliwatt)
    
  • Low Frequency Sinewave Generator
    
  • Automatic Charger for Battery Operated Hi-Fi Preamps
    
  • Six-channel Mixer and Amplifier
    
  • Audio Signal Source
    
  • Analog VU meter
    
  • Voltage controlled amplifier
    
  • Audio graphic equaliser
    
  • Intercom preamp
    
  • FET audio mixer
    
  • Microphone mixer
    
  • Tone control
    
  • Digital volume control
    
  • Sound level meter
    
  • Very loud beeper (PDF)
    
  • Digital noise generator (PDF)
    
  • Tone display system
    
  • Tube amplifier
    
  • Condenser microphone hookup
    
  • Phase shifter
    
  • Paradoxical Sound Syntheizer
    
  • Digital volume control
    
  • Electronic attenuator
    
  • Speech recorded using ISD2560
    
  • Precision audio millivoltmeter
    
  • Automatic loudness control
    
  • Three channel audio spectrum analyzer
    
  • Base / treble control circuit using LM1036N
    
  • Cuckoo sound generator
    
  • Room noise detector
    
  • Various tube crossover circuits
    
  • Minimum Theremin Kit Schematic
    
  • Bias circuits
    
  • Audio line isolator
    
  • Dynamic microphone to electret microphone input
    
  • Line level signal to microphone input adapter
    
  • Simple two line output combiner
    
  • Electret microphone powering circuits
    
  • Use amplifier phono input as line level input
    
  • Speaker signals to line level inputs
    
  • Spring reverb unit
    
  • Sine wave generator
    
  • Simple amplifier
    
  • 3-Band equalizer
    
  • 6-Input mixer
    
  • Doorphone intercom
    
  • Stereo line driver
    
  • Audio notch filer
    
  • Peak reading audio level meter
    
  • Tone control
    
  • Speaker Microphone Circuit
    
  • Electronic canary
    
  • Electronic siren
    
  • Analog Synth Keyboard Schematic
    
  • Weird Sound Generator
    
  • Microphone phantom power supply
    
  • Voltage Controlled Mixer w/Modulator
    
  • Dual Voltage Controlled Oscillator w/Modulator
    
  • Dual Voltage Controlled Filter w/Modulator
    
  • Stereo Ducker
    
  • MS Stereo Decoder
    
  • MS Stereo Microphone
    
  • RIAA Equalized Stereo Phono Preamp
    
  • Tube active crossover
    
  • Improved PL tone decoder
    
  • Magnetic cartridge amplifier
    
  • LM358 preamp
    
  • Sound detector
    
  • Tone detector
    
  • Tone generator
    
  • Warbler
    
  • Audio Detector Circuit
    
  • Voltage Controlled Panner
    
  • Guitar Reverb Effect Version 2
    
  • Stereo Audio Isolator
    
  • Panner Waveform Generator
    
  • Voltage Controlled Panner
    
  • Low Noise Microphone Preamplifier
    
  • Bridging Adapter For Power Amplifiers
    
  • Simple Surround Sound Decoder
    
  • Simplest Ever Amplifier Bridging
    
  • Stereo Width Controllers
    
  • Power Amplifier Clipping Indicator
    
  • Phono Preamps For All
    
  • Digital Delay Unit For Surround Sound
    
  • Parametric And Sub-Woofer Equaliser
    
  • High Quality Sound Mixer
    
  • Loudspeaker Protection and Muting
    
  • Direct Injection Box for Recording & PA Systems
    
  • Minimalist Discrete Hi-Fi Preamp
    
  • Signal Detecting Auto Power-On Unit
    
  • Load Sensing Automatic Switch
    
  • Amplifier thermal protection
    
  • Active Sub-Woofer and Controller
    
  • Balanced Line Driver & Receiver
    
  • VU And PPM Audio Metering
    
  • Variable Amplifier Impedance
    
  • Linkwitz Cosine Burst Generator
    
  • Low Noise Balanced Microphone Preamp
    
  • Fast Audio Peak Limiter
    
  • Subwoofer Equaliser
    
  • Arc welder sound simulator
    
  • Telephone ring sound simulator using SMT (surface mount technology)
    
  • Stereo LED VU meter using discrete components (BC547 transistors)
    
  • Surround Sound Decoder Mk2
    
  • Audio mixer
    

  Miscellaneous schematics

  • Mobile APRS / GPS tracking system
    
  • Electronic fish lure
    
  • Ultrasonic sound receiver
    
  • Experimental data transmitter for fiber optics
    
  • Experimental fiber optic receiver
    
  • Ion detector
    
  • Darkness monitor
    
  • Electroscope
    
  • Simple event counter
    
  • Geiger counter
    
  • Light detector
    
  • Short-circuit beeper
    
  • LM 1800 FM stereo decoder
    
  • Glitch detector
    
  • MAX924 bar-graph level gauge
    
  • Ultrasonic generator
    
  • Negative ion generator
    
  • ELF Monitor
    
  • Laboratory Control System for Cold Atom Experiments
    
  • Chaos generator
    
  • Simple BFO metal detector
    
  • Voltage Comparator Information And Circuits
    
  • Light Activated Detector Circuit (LM393/LM555)
    
  • PL tone generator (NE567)
    
  • Full-duplex doorphone with 3 wires connection
    
  • G Strain energy absorber
    
  • RDS Encoder
    
  • RDS Encoder
    
  • Ultrasound detector
    
  • Discrete Set/Reset Flip Flop
    
  • Monostable Flip Flops (one shot)
    
  • Discrete Bistable Flip Flop
    
  • Sony RS-422 ADAT sync cable pinout
    
  • Garmin Foretrex 101,201, Forerunner 101,201 to Serial DB9 cable schematic pinout
    
  • Biasing Op-Amps into Class A
    
  • Bleeper box for time reference
    
  • Analog computer
    
  • BayComm packet modem
    
  • Morse monitor
    
  • HamComm modem interface
    
  • Morse paddle keyer
    
  • UV light box
    
  • Hardware Random Bit Generator
    
  • Random noise generator
    
  • Analog pulse counter
    
  • Analog opto-isolator
    
  • Pulse width modulators (PWM)
    
  • Pulse width to voltage converter
    
  • Fantastic Atom Expander
    
  • Black Light
    
  • Computerize Your Room/Home
    
  • Flash slave trigger
    
  • Suddent ionospheric disturbance (SID) receiver
    
  • Magnetic levitation device
    
  • Tesla power receiver
    
  • Lazer Tag Equipment Modifications
    
  • Garmin GPS data interconnect
    
  • Inexpensive APRS Weather Station
    
  • Walking robot
    
  • Basic op-amp circuits
    
  • Ion detector
    
  • 1uS light pulse descriminator plus F to V converter (PDF)
    
  • Broadband 2MHz optical fiber receiver (PDF)
    
  • Modulated light received (PDF)
    
  • 1uS light pulse receiver plus post amp (MISC)
    
  • Broadband 5MHz optical fiber receiver (PDF)
    
  • High-speed light receiver (PDF)
    
  • Basement doorbell beeper (PDF)
    
  • Time to dust indicator (PDF)
    
  • Low-power optical interrupter (PDF)
    
  • Simple nitrogen spark generator (PDF)
    
  • Ultrasonic transducer oscillator circuit
    
  • Build logic gates using discrete parts
    
  • Jacob's Ladder
    
  • Circuit for gold wafer card
    
  • Keys finder
    
  • Electronic Eavesdropping Devices Detector
    
  • Lightning Detector
    
  • Geomagnetic field detector
    
  • Seismic detector interfaces to datalogger
    
  • Miniature magnetic gun (rail gun)
    
  • High voltage stun gun
    
  • Mini efficient magnetic coil launcher from disposable camera flash
    
  • Sudden Ionospheric Disturbance (SID) Receiver
    
  • A selection of robotics projects
    
  • Bat detector (new)
    
  • Vat detector (old)
    
  • Variety of quick designs
    
  • Gold wafer (smartcard) programmer
    
  • Making a FRED photopopper
    
  • GPS receiver support kit
    
  • Griffith Observatory Tesla Coil
    
  • Fogger smoke machine
    
  • Dinsmore 1490 digital compass
    
  • Geiger counter
    
  • Electric field disturbance monitor
    
  • Inexpensive seismometer project
    
  • Digital dial
    
  • How to Make a Roomba Serial Interface
    
  • Doorbell for the Deaf
    
  • Electromagnetic field detector
    
  • Insect Repellant
    
  • High Quality Intercom
    
  • Magnetic Gun.
    
  • Metal detector
    
  • Static Electricity / Negative Ion Detector
    
  • Ultrasonic dog whistle
    
  • 2D3 Nixie clock Schematic
    
  • Popular Electronics Ultrasound Detector
    
  • An Inexpensive X-ray Machine
    
  • Navigator 555A radio direction finder (RDF) circuit diagram
    
  • Magnetic levitation circuit
    
  • u-Blox GPS receiver board
    
  • Assorted digital circuits
    
  • Basic electronic circuits
    
  • Miscellaneous simple circuits
    
  • Digital Call Sign Annunciator
    
  • Monitor output from Motorola Oncore GPS engine in HP Z3801A in GPS Disciplined Oscillator
    
  • Ultrasonic switch
    
  • Sound finding cricket with phase detector
    
  • Sound finding cricket
    
  • Common Ground for Older VPW Circuit
    
  • Very basic circuits
    
  • Bat detector
    
  • FCTS Project
    
  • Count Accumulator for Radiation Levels (CARL)
    
  • Modifications for CDV700 Geiger Counter
    
  • Smooth Tone Clickless CW Sidetone Generator
    
  • Lightning Activated Camera Shutter Trigger
    
  • Big Ear Stereo Parabolic Microphone
    
  • Ultra Low Power LCD Indicator
    
  • 12 Volt Toilet Tank Refiller
    
  • Morse Code Beacon Keyer
    
  • Lightning Activated Camera Shutter Trigger
    
  • Cost Effective Multi-Spectral Scanner for Natural Gas Detection
    
  • Simple metal detector electronic circuit
    
  • Metal detector Mk1 - find hidden treasure at the beach
    
  • Metal detector Mk2 - More sophisticated 5 transistor metal detector (BC547, BC557, BC338)
    
  • Driving N-channel FETs from TTL
    
  • Morse Code Practice Keyer 1
    
  • Morse Code Practice Keyer 2
    
  • 741 Light Sensor
    
  • Fluid level detector
    
  • The Aisin-Seiki GPS-Receiver (The "US$20 GPS")
    
  • Morse code display
    
  • Cloud charge monitor (PDF)
    
  • Intercom schematic
    
  • Scaling ADXL50 accelerometer output
    

  Model and remote control schematics

  • autopilot: Do it yourself UAV
    
  • Snake throat muscle controller
    
  • Handy cricket for robotic applications
    
  • Traffic light controller with 20-output sequencing
    
  • 556 Timer Stall-Motor Switch Machine Drivers
    
  • 5 Times Around Circuit
    
  • Audible Train Approach Warning Circuit
    
  • Across The Track Infrared Detectors
    
  • Automatic Reversing Circuit - Mk IV
    
  • Rail Crossing Diamond Protection Circuit
    
  • Automatic Railway Grade Crossing Flashers
    
  • Incline Railway Control Circuit
    
  • Model Railroad Odometer Car
    
  • Turnout Anti-Derail Protection Circuits
    
  • Various Transistor Throttles Cicuit Schematics
    
  • Three Terminal Regulator Type Throttle (LM350K)
    
  • Timed Uncoupling Ramp Driver (LM555)
    
  • Grouped DCC Block Occupancy Detectors
    
  • First Across The Line Race Scorer Circuits
    
  • School Bus Signals Circuit
    
  • Timed DC Throttle
    
  • DCC - Zero Stretching Simulator (LM555)
    
  • A Receive Signal Decoder
    
  • 27Mhz toy car receiver
    
  • 27Mhz toy car transmitter
    
  • One ounce rocket ejection timer
    
  • LED traffic lights
    
  • Proportional radio remote control
    
  • Alf: The Robotic Matchbox car
    
  • Seaplane schematic
    
  • Model Rocket with Video Camera
    
  • Signal breaking module
    
  • Animatronic Snake Throat Muscle Controller
    
  • Electronic millipede robot
    
  • Downed model locator
    
  • Precision Receiver Battery Low Voltage Alarm
    
  • Launch controller for multiple rockets
    
  • Discharger for Receiver Battery Packs
    
  • RC Receiver Battery Low Voltage Alarm
    
  • Downed model locator Mark 2
    
  • Robot with PIC16F84 brain & InfraRed eyes
    
  • 0-10V control for RC servos
    
  • Robotic microcontroller board
    
  • Multi Rocket Launcher
    
  • Model rocket launch controller
    
  • Pad launch controller for model rockets
    
  • Simple flashing light circuit
    
  • Simple flashing light circuit
    
  • A dual alternating flashing light circuit
    
  • Simple flashing light circuit
    
  • A dual tandem flashing light circuit powered by a 9 volt battery
    
  • Simulate the Gyralite (dual flashing headlights).
    
  • Simple train detector using ambient light and a photocell
    
  • R/C digital camera controller
    
  • R/C helicopter camera
    
  • Building an RF Remote Control System
    
  • Motor walker circuit
    
  • 250-amp Speed Controller for RC cars
    
  • Level crossing for model railways
    
  • Building a robot arn using Nitino muscle wire
    
  • Signal module for model railways adds a high degree of realism
    
  • Simple throttle control ideal for railway shuting yards or a second main track line
    
  • Spider robot electronic project page
    
  • Two tone train horn
    
  • R/C Emergency locator alarm
    
  • Remote switch for radio-control aircraft accessories
    
  • Angelfire rocket GPS payload
    
  • Radio Control Battery Backup
    
  • Glow Plug driver for model engines
    

  Motor and general control schematics

  • Bridge head
    
  • PWM motor controller
    
  • Transistor relay driver
    
  • Latching relay driver
    
  • Relay delay circuit
    
  • Touch switch
    
  • Low voltage DC motor speed controller
    
  • Flashing neon christmas lights
    
  • Three input first response monitor
    
  • Switch-on delay circuit
    
  • Electronic thermostat
    
  • LM3911 temperature controller
    
  • Programmable light-activated relay
    
  • Simple 10 Stage Control Box
    
  • One component stepper motor driver
    
  • Dual Stepping motor drivers using UDN2540
    
  • PWM DC motor control with SG3525
    
  • Stepper Motor Driver using TEA3718/3717
    
  • Microstepping with PBM3960 and TEA3718
    
  • DC Motor Driver with L6203
    
  • Stepper Motor Driver using L298 and L297
    
  • Several stepper motorol control circuits
    
  • Wireless RF PWM dual motor controller
    
  • H Bridge Motor Control Circuits
    
  • HIGH or LOW Power Switch For Lights or Small Motors
    
  • Push Button Motor Control Circuits
    
  • Motor speed controllers
    
  • Electronic Thermostat Relay Circuit
    
  • Interfacing 5 volt CMOS to 12 volt loads
    
  • Light Activated Relay
    
  • CMOS Toggle Flip Flop With Relay(CD4013)
    
  • 555 Timer Monostable Circuit Using Pushbutton
    
  • Dual Channel Servo Pulse to H-Bridge Interface
    
  • Current loop interface
    
  • Switching solenoid driver
    
  • Modular relay system
    
  • Light/dark detector
    
  • Pulse Width Modulation DC Motor Control
    
  • Stepper motor controller
    
  • Touch switch
    
  • Anti-jam system for rotary diecut machine based on PIC16F84
    
  • Bridge control for PLC using PIC18F84
    
  • H-Bridge motor controller (5 amps, 100 watts)
    
  • Dual Channel Servo Pulse to H-Bridge Interface
    
  • Servo pulse to PWM converter
    
  • Rolling code 4-channel UHF remote control
    
  • Pushbutton one-shot and latch (PDF)
    
  • Charge coupled bi-directional power MOSFET relay (PDF)
    
  • Finger touch activated switch (PDF)
    
  • Machine vibration triggers hour meter (PDF)
    
  • Solid state relay (PDF)
    
  • Line-powered Xenon flash transmitter (PDF)
    
  • 9V Xenon photoflash controller (PDF)
    
  • No-Hum Fan Controller
    
  • AC switching with TRIAC from TTL
    
  • Control 120VAC relay with TTL
    
  • Driving a relay with a CPU
    
  • Power-line Appliance Controller
    
  • Solid-state power controller
    
  • High And Low Voltage Cut Off With Time Delay
    
  • Optically isolated stepper motor controller
    
  • Stepper motor controller
    
  • 35KHz Magnetic-Radiation Remote-Control
    
  • Voice activated switch using MC2830
    
  • Combination-controlled, fully customizable RF remote control
    
  • Thermoelectic controller (scriptable thermometer)
    
  • Stepper motor positioner
    
  • Thermostat
    
  • Frequency switch
    
  • PIC16F84 RF remote controller
    
  • H-Bridge shematic
    
  • DS1821 programmable thermostat
    
  • Hot Water Tank Indicator
    
  • Temperature monitor
    
  • Cold activated switch
    
  • Voltage comparator switch
    
  • Dark activated switch
    
  • DC Push Button Motor Control Circuit
    
  • Light detector
    
  • DC Motor Reversing Circuit
    
  • Sound operated switch
    
  • LDR light/dark activated relay switch
    
  • Touch Switches
    
  • 6090 digital decoder schematics
    
  • Assorted relay control circuits
    
  • Adjustable Voltage motor controller
    
  • Serial servo controller
    
  • DC Motor-Driver H-Bridge Circuit
    
  • Constant Temperature Circuit
    
  • PWM Motor Speed Controller / DC Light Dimmer
    
  • Constant Temperature Circuit
    
  • PWM DC Motor Speed Control
    
  • Solenoid starter
    
  • MOSFET based speed controller uses 9 IRFZ40 power MOSFETS
    
  • CO2 controller for planted tanks
    
  • Light activated relay
    
  • Delayed shutter control for Kodak DC-20
    
  • Gasoline generator automatic throttle controller
    
  • MOSFET H-BRIDGE schematic and theory
    

  Music related schematics (also see Audio)

  • Audible metronome
    
  • Visual metronome
    
  • Peak-reading meters
    
  • Octave screamer
    
  • Amiga MIDI interface
    
  • Apple Mac to MIDI synthesizer interface cable
    
  • Apple Macintosh MIDI interface schematic (basic version)
    
  • Apple Macintosh MIDI interface schematic (deluxe version)
    
  • Standard MIDI to MIDI interface cable diagram
    
  • Simple MIDI switcher
    
  • MIDI interface / cable tester
    
  • MIDI keyboard
    
  • MIDI merger schematic
    
  • 25-pin PC serial port to MIDI synthesizer interface cable
    
  • 9-pin PC serial port to MIDI synthesizer interface cable
    
  • Serial MIDI interface
    
  • Microcontroller MIDI interface
    
  • MIDI keyboard circuit
    
  • Spring reverb unit
    
  • MP3 Player
    
  • Simple colour organ
    
  • Guitar fuzz effect
    
  • 8 note tune player
    
  • Colour (Sound) Organ
    
  • Transisor organ
    
  • BookPC Car MP3 Player
    
  • Yet Another Mobile MP3 Player
    
  • Wave Multiplier for music synthesizers
    
  • Miniature metronome
    
  • Zonk Machine and Treble Booster
    
  • Simple line mixer
    
  • Simple MIDI tester
    
  • MIDI Controller Footpedal
    
  • DIY Serial MIDI Interface (80C51/80C31 Version)
    
  • Electronic metronome
    
  • Sound Effects Generator
    
  • Sound Effects Generator 2
    
  • Sound Lab Mini-Synth Guitar Trigger
    
  • Digital Guitar Tuner
    
  • Drum tone oscillators
    
  • Analog MIDI synthesizer
    
  • Spring reverb
    
  • MIDI to CV interface
    
  • Dual phantom power pre-amp
    
  • Four channel fuzz box
    
  • Theremin controller
    
  • Vocal zapper
    
  • MIDI drum machine project
    
  • MIDI Drum Machine Analog Input Schematic
    
  • Guitar Reverb Pedal
    
  • Guitar Tremolo Unit
    
  • Spring Reverb Unit For Guitar
    
  • Ultra Simple Bass Guitar Compressor
    
  • Vox AC30 Guitar Amplifier Simulator
    
  • Guitar Vibrato Unit
    
  • Musical Instrument (Expandable) Graphic Equaliser
    
  • Midibox 64
    

  PC related schematics

  • I2C printer port adaptor
    
  • RS232C Level Converter
    
  • PC electrically isolated RS422 interface using SN75176B or MAX485
    
  • PC electrically isolated RS485 interface using MAX487 or SN75176B
    
  • Short circuit protected power supply from PC 12V supply
    
  • Isolated Full Duplex RS232C Interface
    
  • RS232 DB-9 switch to flip between two serial ports
    
  • DB-9 Connector to DB-25 (both RS-232)
    
  • Mac Serial Port (RS-422 DIN-8) to RS-232 DB-25
    
  • Modem Rockwell RCV336/ACF model V1433VQR ext.
    
  • Genius Mouse schematics
    
  • Commodore 64 24-bit parallel port interface with 8255
    
  • Sound Card Interface with Tone Keyer
    
  • Ericsson phone to PC serial port interface
    
  • PC serial port receiver
    
  • Parallel port relay interface
    
  • Digital cameras (AGFA, Olympus) to PC (COM) cable pinout
    
  • Mac to HP48 cable pinout
    
  • Serial port temperature datalogger
    
  • Game boy camera PC serial interface
    
  • Jupiter card programmer
    
  • Parallel (Printer) Port Interface
    
  • RS-232 line monitor and loopback cables
    
  • The KD2BD Pacsat Modem
    
  • SWTP PR-40 Printer Interface Schematics
    
  • A Serial Infrared Remote Controller
    
  • PC Serial and Parallel Port Software and Interfaces
    
  • Interfacing 16x2 character :LCD to parallel port
    
  • RS-232 Protocol Analyser
    
  • Interface cable for Casio QV-200 digital camera
    
  • Radio clock for PC's
    
  • 4-channel 8-bit analog-to-digital converter for PC
    
  • Printer port ADC
    
  • Parallel port ADC based on MAX147
    
  • Analog Signal Acquisition for PC Printer Port
    
  • More accurate PC/AT clock
    
  • Getting power from RS-232 interface
    
  • Barcode scanner
    
  • SmartCard PC Emulator
    
  • Relay interface add-on board for PC
    
  • 8-way relay interface board for PC parallel printer port
    
  • Stepper motor controller for PC parallel port
    
  • 3-axis stepper motor controller for PC parallel port
    
  • PC based thermometer based on Dallas DS1621
    
  • Simple PC thermometer for serial port but using R/C network for measurement
    
  • Dallas DS1620 based USB Digital Thermometer
    
  • PC thermometer using PC game (joystick) port
    
  • iRDA interface for motherboard using Vishay TFDS4500
    
  • LCD2LPT with LIRC (LCD to LPT printer port) interface
    
  • FM radio with PC parallel port interface
    
  • Build your own iRDA SIR Transceiver (Dongle) using MCP2120
    
  • PC thermometer
    
  • Dive computer interface
    
  • Parallel port servo controller
    
  • GPS receiver (Gamin, Eagle etc) to PC interface cables
    
  • Connect two CD-ROM drives to one soundcard
    
  • Headphone driving circuit for soundcards
    
  • Get power out of PC parallel port
    
  • Null Printer Adapter
    
  • PC speaker volume control circuit
    
  • How to get power from PC to your circuits
    
  • RS-232 surge protection
    
  • Simple RS-232 serial port buffer circuit
    
  • Get power out of PC RS-232 port
    
  • Sound Blaster Microphone Preamplifier
    
  • Sega 3D glass interfacing circuits
    
  • Convert Atari-style joystick to PC joystick port
    
  • Fake Joystick circuit
    
  • Using the joystick port as general purpose input
    
  • Connect other circuits to PC joystick port
    
  • Schematic of a standard PC joystick
    
  • Simple PC SmartCard reader
    
  • Fax to modem interface
    
  • Analog to Digital Conversion (ADC) and Communicating with a PC
    
  • Temperature sensor for PC
    
  • PC interface for point controller
    
  • PC-based ISA data acquisition and control board
    
  • Linux Infra-red Remote Control (LIRC)
    
  • Homebuilt RS232 LCD Interface
    
  • USB I/O interface board for PC
    
  • Compter microphone
    
  • CCD linear image sensor to PC parallel interface
    
  • Laptop Computer Serial Port Power Booster
    
  • Assorted computer interface circuits
    
  • HamComm Interface
    
  • Apple II/II+/IIe IDE Drive Interface
    
  • Basic Stamp I & PC Relay Controller
    
  • RS-232 to TTL cable
    
  • Hi-Fi PC Speaker System
    
  • How to construct Garmin GPS receiver interface cables
    
  • iRDA printer adapter
    
  • http://www.teaser.fr/~amajorel/jasmin/
    
  • 160 Baud ALDL Hardware Interface
    
  • AT PC Power Supply 1
    
  • AT PC Power Supply 2
    
  • AT PC Power Supply 3
    
  • AT PC Power Supply 4
    
  • AT PC Power Supply 5
    
  • iLINK Interface
    
  • Digital Signals Decoding Interfaces
    
  • 9-pin null modem cable
    
  • RS232 - Lowe HF-225 interface
    
  • RS232 to IrDA convertor using Vishay TOIM3232
    
  • Interfacing PC sound card to SSB rig
    
  • Supply Derives Power From 3-Wire RS-232 Port
    
  • 24-line PC digital interface (PDF)
    

  PDA interfaces and related schematics

  • Palm Keyboard interface board
    
  • Casio interface circuits
    
  • SHARP palm-top/hand-held to RS232 serial converter
    
  • Fitting a JTAG interface to an iPAQ 3600
    
  • Apple iPod dock pinout
    
  • Casio calculator interface schematic
    
  • Palm Pilot, Palm III, V, VII, VIIx, Handera interface port pinout
    
  • Interfacing ultrasonic range finder to BrainStem
    
  • Hamamatsu UVTron Interface to a BrainStem
    
  • Casio datalogger
    
  • Casio datalogger
    
  • Interfacing ADXL202 accelerometer to PalmPilot
    
  • PalmPilot audio interface
    
  • PalmPilot cradle to modem adapter
    
  • PalmPilot connector pinouts
    
  • PalmPilot serial port interface
    
  • PalmPilot memory schematics
    
  • Aladin interface
    
  • PalmPilot turbo boost guage interface
    
  • MIDI interface for PalmPilot
    
  • IBM PC keyboard to PalmPilot interface
    
  • Aladin interface using op-amp
    
  • Wireless local network for PalmPilot (large PDF)
    

  Power supplies and control schematics

  • Power supply provides +5VDC regulated, +10VDC unregulated and 7.5VAC
    
  • 13.5KV power supply
    
  • Kirlian device supply
    
  • LM317 adjustable power supply
    
  • LTC1265 Nicad charger
    
  • Single cell lithium battery charger
    
  • Smart battery charger
    
  • Battery charge indicator
    
  • Lead acid trickle charger
    
  • 12B Battery condition indicator
    
  • Alkaline battery charger
    
  • Regulated Power Supply Circuits
    
  • Basic Solid State Relays
    
  • High Side Current Monitors (LM358, Zetex - ZXCT-1009)
    
  • Low Battery Voltage Cutout Circuits
    
  • Alternative power source for Magellan GPS receivers
    
  • Dynamo Current and Voltage Regulator
    
  • Generating Negative 5 Volts from 9 Volt Battery
    
  • LED Battery Condition Indicator
    
  • LM317 Variable Voltage Regulator
    
  • LM317 Regulator With Pass Transistor
    
  • High Current Regulated Power Supply
    
  • Simple Variable Voltage Source
    
  • Various switching power supplies
    
  • Variable 3 - 24 Volt / 3 Amp Power Supply
    
  • 2 watt switching power supply
    
  • Variable Voltage and Current Power Supply
    
  • Low Power DC to DC Converter
    
  • Constant Current Battery Charger
    
  • Intelligent NiMH/NiCd switched mode fast charger
    
  • Nicad battery charger
    
  • Simple power supply
    
  • Voltage converter
    
  • Bench power supply
    
  • Easy power supply
    
  • Valve power supply
    
  • 6V to 12V Converter
    
  • Tesla coil / HV generator
    
  • High Current Power Supply
    
  • Dual Polarity Power Supply
    
  • High Voltage High Current Power Supply
    
  • Transformerless Power Supply
    
  • Fixed Voltage Power Supply
    
  • Voltage Inverter
    
  • Voltage Inverter
    
  • Dual power supply
    
  • Negative voltage generator
    
  • Voltage doubler
    
  • Power reminder beeper (PDF)
    
  • Unplugged power cord alarm
    
  • Machine power loss beepter (PDF)
    
  • Low-dropout 12V regulator (LM324)
    
  • HV supply: 12VDC in, 12KV out
    
  • Generating -5VDC from +5VDC
    
  • Filtering PC bus POWER
    
  • Bidirectionall power inverter
    
  • Nagative voltage generation using 555 timer
    
  • Flyback transformer driver
    
  • Basic UPS Power Supply
    
  • Fuse monitor / alarm
    
  • 500W low cost 12V to 220V inverter
    
  • TTL power supply with crowbar protection
    
  • Pulse Charger for reviving tired Lead Acid batteries
    
  • High current regulated power supply
    
  • CEMF (counterelectromotive force) charger
    
  • Ignition Coil High Voltage Generators
    
  • One 9V battery gives +18, +25, +33V
    
  • +9V *and* -9V from one battery
    
  • Adjustable power supply using LM317
    
  • Simple +5V power supply circuit
    
  • 12 Vdc - 120 Vac Inverter Schematic
    
  • +12V/-12V Power supply unit
    
  • +/-12V to +/-5V Power unit
    
  • +5V Switching regulator (1)
    
  • Switching regulator (2)
    
  • Electric power controller
    
  • +30V power supply with +5V
    
  • +30V DC-DC converter
    
  • DC/AC inverter (2)
    
  • DC/AC inverter (1)
    
  • PIC16F873 DC motor speed controller
    
  • 12V 30A power supply
    
  • Dual regulated power supply
    
  • Fuse blown indicator
    
  • Gyrator circuit
    
  • Variable power supply
    
  • LM317 Regulator Circuit
    
  • Nicad battery charger
    
  • Regulated 12V supply
    
  • Unregulated power supply
    
  • Snowmobile GPS power adapter
    
  • Simple switching power supply
    
  • Assorted power source and control circuits
    
  • 12 volt battery monitor
    
  • 12 volt power supply
    
  • 5 volt power supply
    
  • Battery voltage monitor
    
  • LM3914 battery monitor
    
  • Multiple voltage power supply
    
  • Voltage doubler
    
  • Voltage inverter
    
  • PWM DC Motor Speed Control
    
  • Battery Low Voltage Beeper
    
  • PWM Motor Speed Controller / DC Light Dimmer
    
  • PWM Motor/Light Controller
    
  • Low Power LED Voltmeter
    
  • Temperature Controlled Nicad Charger
    
  • PWM Motor/Light Controller
    
  • PWM Motor/Light Controller variants
    
  • Low Power LED Voltmeter
    
  • Temperature Controlled NICD Charger
    
  • Simple Capacitance Multiplier Power Supply For Class-A Amplifiers
    
  • Simple DC Adapter Power Supply
    
  • Variable Dual Lab Power Supply
    
  • Two amp variable power supply
    
  • Automatic AA nicad battery charger
    
  • Battery charge for 12V SLA batteries
    
  • Turn an ordinary wall wart / plug-pack into a regulated device
    
  • Battery Charger Ideas
    
  • Power control for arc welders and other inductive loads
    
  • Charger for gel lead acid batteries
    
  • Compressor-mate power protection for refrigerators, freezers and air conditioners
    
  • Battery Characterizer
    
  • Nicad Battery Discharger/Capacity Indicator
    
  • 200 Watt Modified PC Power Supply 13.5 Volt 14 Amp
    

  Radio-frequency schematics (also see Transmitters)

  • UHF oscillator
    
  • Economoy short-wave radio
    
  • Linearized RF detector
    
  • Two-band radio
    
  • Shortwave conveter for scanners
    
  • FM Bug
    
  • AM Radio
    
  • Toroidal coil RF shortwave receiver
    
  • Crystal radio
    
  • CW RECEIVER 40/80 meter CW receiver
    
  • WLW 500KW Transmitter Schematic
    
  • AM-Receiver for Aircraft communication (118.250MHz)
    
  • AM receiver for aircraft communications
    
  • 45-860MHz Radio receiver based on UV916-tuner
    
  • 80 Meter CW ARDF receiver
    
  • Four channel RF remote control
    
  • Receiver building blocks
    
  • Simple wireless radio data link
    
  • RX3302 receiver module schematic
    
  • Superregenerative 27MHz receiver
    
  • 49MHz walkie-talkie
    
  • Convert 2m VHF FM PMR transceiver Motorola Radius M110 into an amateur radio
    
  • Vibrating pocket bug detector
    
  • Simple Op-Amp Radio
    
  • UHF - 100W Transistorized amplifier
    
  • 50MHz Converter
    
  • RF front-end for triple conversion GPS receiver
    
  • 2M - 20M transverter
    
  • Improved CMOS RF PLL sythesizer
    
  • Harmonic oscillator
    
  • Direction finder system
    
  • One transistor regenerative receiver
    
  • Synthesized HF receiver
    
  • TBA120 narrowband FM receiver
    
  • TDA7000 receiver
    
  • ZN414 receivers
    
  • 10W HF linear amplifier
    
  • 500W HF linear amplifier
    
  • 3W HF QRP linear amplifier
    
  • Phasing SSB exciter
    
  • 500mW HF linear amplifier
    
  • Generic VHF power amplifier
    
  • 10.7MHz FM detector
    
  • RTTY terminal unit
    
  • Q-multiplier
    
  • CMOS RF PLL sythesizer
    
  • 3W FM Transmitter
    
  • Crystal radio
    
  • Op-Amp Radio
    
  • Class B series modulator
    
  • Advanced VHF power meter
    
  • The MRX-40 Mini Receiver
    
  • External antenna for the GPS-38, Magellan 2000, or Eagle Explorer GPS receivers
    
  • Bug detector
    
  • 175KHz inductive pulse receiver (PDF)
    
  • 200-400 MHz voltage controlled oscillator
    
  • AM/FM/SW active antenna
    
  • RF Sniffer under 0.5MHz to above 500MHz
    
  • Demodulator Schematic/Design
    
  • 73MHz remote controller hallogen light
    
  • CB (27MHz citizens band) receiver
    
  • CB (27MHz citizens band) 2.5W transmitter
    
  • AM to FM conveter
    
  • AM BCB radio receiver
    
  • Regenerative shortwave receiver
    
  • 7MHz SSB Transceiver
    
  • Frequency Synthesizer
    
  • Digital Automatic Gain Control (AGC)
    
  • PLL synthesizing oscillator (1)
    
  • PLL synthesizing oscillator (2)
    
  • PLL synthesizing oscillator (3)
    
  • 2N2222 40 Meter CW/DSB Transceiver
    
  • Yaesu FT-736R doppler compensation
    
  • Phased lock loop schematic
    
  • 30M PSK31 Transceiver
    
  • SOP receiver (PDF)
    
  • SOP direct conversion receiver
    
  • Receiver
    
  • 30m direct conversion receiver
    
  • Popcorn direct conversion receiver
    
  • 40m direct conversion receiver
    
  • 80m direct conversion receiver
    
  • Huge LED Antenna Direction Display (part 1)
    
  • Huge LED Antenna Direction Display (part 2)
    
  • 136 kHz direct conversion receiver
    
  • One Watt 2.45 GHz Linear Amplifier
    
  • 222 MHz Transverter
    
  • VFO from 2001 ARRL Handbook, page 17.74
    
  • VFO from 2001 ARRL Handbook, page 14.20
    
  • Assorted RF circuits
    
  • 14MHz SSB 10mW Transceiver
    
  • Building a Simple LF Exciter
    
  • Yaesu band decoder schematic
    
  • VLF radio receiver schematic
    
  • VLF Upconverter for Shortwave Receiver
    
  • 5 watt, 80 meter QRP CW Transceiver
    
  • How to Build a 300MHz AM, RF Remote Control System
    
  • RF Modem Robotics Project
    
  • PLL FM transmitter
    
  • ICOM CI-V interface with RS232 RTS to PTT
    
  • Improved FM Stereo Modulator
    
  • Morse Code Beacon Keyer
    
  • QRP Antenna Tuner
    
  • Smooth Tone Clickless CW Sidetone Generator
    
  • Smooth Tone Clickless CW Sidetone Generator
    
  • Variety of receiver converter projects
    
  • One transistor FM receiver
    
  • 42 Mc Band to 88 Mc Band (retrofit converter) Project
    
  • Crystal radio circuits including diode performance comparison
    
  • 50MHz Assistant (Preamp & Power Amp.)
    
  • Bug detector
    
  • Basic RF oscillator
    
  • Radio Control Electric Switch
    
  • 56K RF Modem
    
  • 80M ARDF direction finder
    
  • Kenwood TR-7950 manual & schematics (PDF)
    

  Solar-power schematics

  • Sun tracking circuit for solar arrays
    
  • Solar power recharger
    
  • Solar power supply
    
  • Photovoltaic Solar Battery Regulator and Load Controller
    
  • Solar charge controller
    
  • Solar robots
    
  • Digital Clock with Timer and Solar Panel Regulator
    
  • Solar Tracker
    
  • 1381 solar engine
    
  • D1 solar engine
    
  • FLED solar engine
    
  • PM1 solar engine
    
  • Solar car array controller schematic
    
  • Solar car battery monitor schematic
    
  • Solar car brake controller schematic
    
  • Solar car main controller schematic
    
  • Solar car display controller schematic
    
  • Solar car electrical design and circuit index
    
  • Portable solar battery charger
    
  • Sensor Electronic Tracker with H-Bridge Drive
    
  • Sensor Electronic Tracker with Simple Solar Charge Controller
    
  • Solar tracking control system
    
  • LED7 solar tracker
    
  • Solar step-down regulator
    
  • Zener-based solar engine
    
  • AA battery solar charger
    
  • AA battery solar charger
    
  • Buck Mode Switching Regulator for Solar Applications
    
  • Solar Panel Charge Controller / Low Voltage Disconnect Circuit
    
  • Solar Panel Current Meter
    
  • Remote Solar LED light
    
  • SCC2 10 Amp Solar Charge Controller
    
  • 12 Volt 20 Amp Solar Charge Controller
    
  • Solar Charged LED Flashlight
    
  • Self Powered Solar Box Furnace
    
  • SPC2 6 Amp Solar Power Center
    
  • Solar Powered Reading Lamp
    
  • AA battery solar charger
    
  • Solar Panel Charge Controller / Low Voltage Disconnect Circuit
    
  • Solar Panel Current Meter
    
  • 5V regulated solar power supply circuit (uses solar garden light solar panels)
    
  • Solar charger for 12V batteries switch switching based on Zetex ZTX 851
    
  • Solar garden light circuit schematic
    
  • Solar cell Nicad charger
    
  • Solar powered dock lamp flasher
    

  Telephone and intercom related schematics

  • Telephone recording circuit
    
  • Infinity Transmitter Schematic and Plans
    
  • Digisound ring modulator
    
  • Incoming call indicator
    
  • Telephone Ring Generator Using 60Hz Power Transformer
    
  • Telephone Ring Generator Using Switching Power Supply
    
  • Telephone In-Use LED Indicator
    
  • Telephone In-Use Relay Circuit
    
  • Telephone Audio Interface
    
  • Telephone interfacing / caller ID using a PIC microcontroller
    
  • Home made PBX / PABX
    
  • Ringing Phone Light Flasher
    
  • Phone Busy Indicator
    
  • FM Telephone Bug
    
  • Cut Phone Line Detector
    
  • Simple Phone Tap
    
  • Telephone Hold Button
    
  • Telephone Recorder
    
  • 300 baud modem circuit schematic
    
  • 1-line telephone status indicator (PDF)
    
  • Line in use indicator (PDF)
    
  • 4-line telephone status indicator (PDF)
    
  • Caller ID decoder
    
  • Telephone in use light
    
  • Detecting a telephone RING
    
  • Phone In-Use Light
    
  • Phone to audio interface
    
  • Phone Off-Hook Indicator
    
  • 'phone rang' indicator light
    
  • Phone Line to Audio
    
  • Phone in-use
    
  • Telephone Line Monitor
    
  • Use old phones as an intercom
    
  • Phone-In-Use indicator
    
  • Hold function for Telephone
    
  • Digital/Standard Phone Line Tester
    
  • Caller ID decoder part 1
    
  • Caller ID decoder part 2
    
  • DTMF decoder / logger
    
  • Cellular Phone calling Detector
    
  • Phone line in use indicator
    
  • Telephone music on hold interface
    
  • Soft musical telephone ringer
    
  • Telephone amplifier
    
  • Telephone line monitor
    
  • Cut telephone line detector
    
  • FM telephone line bug transmitter
    
  • Simple telephone line tap for intercepting telephone calls
    
  • The Link A2B+1 (the Link Telephone Intercom - DTMF version)
    
  • The Link 4+0 - Internal Intercom
    
  • The Original 2 Phone Intercom Link Design
    
  • 8-line intercom system using 89C51 microcontroller
    
  • Universal telephone hold
    
  • Talking phone dial monitor
    
  • Simple Skype VoIP analog adapter
    
  • Telephone line simulator
    
  • Telephone privacy adapter
    
  • Telephone ringing circuits
    
  • Simple circuit to connect telephone equipment to audio mixer
    
  • NCDS Interface Schematic for Nokia 3110, 8110, 8110i
    
  • Assorted telephone circuits
    
  • Greek telecard reader
    
  • Isolated Telephone Interface (phone tap)
    
  • Phone ring circuit schematic
    
  • Infinity Bug Schematic (remote telephone surveillance)
    
  • Detect when phone line in use and when two telephones are on the same line
    
  • Cut phone line detector
    
  • Telephone autodialler
    
  • Taxi phone automatic dialler
    

  Test equipment circuit diagrams

  • Audible continuity tester
    
  • Wire tracer
    
  • Signal generator for signal tracer
    
  • Electronic level
    
  • Digital volt meter
    
  • Adjustable continuity tested
    
  • RF field strength meter
    
  • Frequency counter
    
  • DCC Ammeter
    
  • High Impedance Voltmeter
    
  • Tri-Waveform Generator
    
  • 220V live wire-in-wall scanner
    
  • Owens Bridge Inductance Measurement Device
    
  • ESR Meter
    
  • Line Output / Flyback transformer tester
    
  • Capacitance meter
    
  • Capacitance meter
    
  • AC Line Current Detector
    
  • Triangle and Squarewave Generator
    
  • Signal tracer / injector
    
  • Conrad Electronics MM3610D multimeter cable pinout
    
  • Grid dip meter
    
  • PCB VSWR bridge
    
  • Electric field & leakage detector
    
  • Simple polarity detector
    
  • RCM710 Electronic Scale
    
  • LASER/LED light output intensity meter (PDF)
    
  • Frequency and capacitance meter
    
  • Elecraft XG2 receiver test oscillator (PDF)
    
  • PIC16F84 based diode tester
    
  • Triple Stroboscope
    
  • Automatic heat limiter for soldering iron
    
  • Ultra-simple voltage probe
    
  • Live line detector
    
  • Continuity tester using transistors
    
  • Latching continuity tester using 4093
    
  • Linear Resistance Meter
    
  • Crystal tester
    
  • Capacitance meter
    
  • Digital voltmeter (DVM)
    
  • Transistor tester
    
  • Function generator
    
  • Triangle / Square wave generator
    
  • Picoammeter circuit schematic with 4 ranges
    
  • Beeper to find short circuits
    
  • MOSFET tester
    
  • Inductive meter adapter
    
  • Crystal tester
    
  • Oscilloscope testing module (Huntron circuit)
    
  • Voltage Monitor
    
  • Logic probe
    
  • TDR cable reflection tester
    
  • Resistor decade box
    
  • Simple light sensor adapter for oscilloscope
    
  • Time Domain Reflectometer (TDR)
    
  • pH Meter
    
  • Multi Wire Cable Tester
    
  • Connection tester
    
  • EMF field probe
    
  • Function generator
    
  • Logic probe
    
  • Zener diode tester
    
  • Mini DDS (direct digital synthesizer)
    
  • AD9850 DDS daughterboard
    
  • Signal Tracer and Injector
    
  • VCR Tuner Based RF Spectrum Analyzer Schematic
    
  • LCD frequency counter (PIC16F84)
    
  • 10Hz - 100KHz D.D.S. Function Generator
    
  • TTL Pulse Reading Logic Probe
    
  • Stereo Test Tone Generator
    
  • Pulse Reading Logic Probe
    
  • Pink Noise Generator for Audio Testing
    
  • Audio Millivoltmeter
    
  • Audio Test Oscillator
    
  • Full Featured Transistor Tester
    
  • Opamp Design and Test Board
    
  • Microphone Circuit Test Oscillator
    
  • Distortion Analyser
    
  • Self Oscillating Amplifier for Distortion Testing
    
  • Capacitance meter that connects to multimeter
    
  • Transistor tester and signal injector
    
  • Continuity tester
    
  • Square wave oscillator (555)
    
  • Capacitance meter
    
  • Continuity tester
    
  • Electrolytic capacitor tester
    
  • RF field strength meter Mk1
    
  • RF field strength meter Mk2 (75MHz to 140MHz)
    
  • LED power meter for testing RF transmitters
    
  • Logic designer and breadboarding system for digital circuits
    
  • Logic probe with integral pulser function
    
  • Logic probe that is essential for servicing digital circuits
    
  • Logic pulser with DIP switch for setting output waveform characteristics
    
  • Build a Magnetic Field Immunity Tester
    
  • 555 Timer IC Tester
    
  • 555 go / no-go tester
    
  • 12V Lead-Acid Battery Monitor
    
  • Continuity tester 2
    
  • Continuity tester
    
  • Logic probe
    
  • Field strength meter for the 137 kHz band
    
  • In-circuit electrolytic tester
    
  • PIC logic probe with pulser
    

  Timing and oscillator circuits

  • Budget timer
    
  • Long period timer
    
  • 555 time delay circuit
    
  • Low frequency clock
    
  • Countdown timer with relay
    
  • DDS using AD9835
    
  • CA4060B Timer Circuits
    
  • Special Function Timer Circuits (LM555)
    
  • 1 Second Time Base From Crystal Osc.
    
  • Power-On Time Delay Relay Circuit
    
  • Low Voltage , High Current Time Delay Circuit
    
  • Power-Off Time Delay Relay Circuit
    
  • Generating a Delayed Pulse With a dual 555 Timer
    
  • Time Delay Relay
    
  • Time Delay Relay
    
  • Line powered 60Hz clock generator (PDF)
    
  • Micro-power pulse generator (PDF)
    
  • Darkroom camera shutter timer
    
  • Divide by 1.5 counter (PFD)
    
  • High-output square wave generator (PDF)
    
  • D Flip-flot one-shot circuits (PDF)
    
  • Clock divider
    
  • Clock doubler
    
  • CMOS oscillator
    
  • Crystal 32.768KHz CMOS Oscillator
    
  • Crystal oscillator
    
  • Cheap 40KHz clock
    
  • Stable 40KHz clock
    
  • 'Rounding Off' a square wave
    
  • Switch debounce using 555
    
  • Square wave to sine wave converter
    
  • Bedside lamp timer
    
  • Sun tanning timer
    
  • Digital Stopwatch 0-99sec
    
  • Digital Stopwatch 0-60sec
    
  • 28 LED clock timer
    
  • Photo timer circuit
    
  • Day / Night / 24 Hour Select Sensor
    
  • One transistor timer
    
  • Variable timer
    
  • Micropower pulse generator (PDF)
    
  • Square wave oscillator
    
  • Triangle wave oscillator
    
  • Sawtooth wave oscillator
    
  • Sine/Cosine wave oscillator
    
  • 555 timer
    
  • 555 oscillator
    
  • Stable multivibrator (IC)
    
  • Stable multivibrator (Transistor)
    
  • Push Button Switch Debouncer
    
  • Square wave oscillator
    
  • 5 to 30 Minute Timer
    
  • NE555 Basic Monostable
    
  • Mini DDS (Direct Digital Synthesis)
    
  • Astable Multivibrator
    
  • High Precision GPS/TV controlled Reference Oscillator
    
  • TV based Receiver for a Standard Frequency Generator
    
  • AD9852 DDS schematic
    
  • A GPS receiver based frequency standard
    
  • Square wave oscillator with fixed frequency steps using 555 timer chip
    
  • Monostable multivibrator
    
  • Clock generator
    
  • 555 Timer Tutorial + Circuits
    
  • Versatile electronic timer
    

  Transmitter schematics (also see RF)

  • Wireless microphone
    
  • XTAL locked tone transmitter
    
  • AM oscillator for wireless microphones
    
  • Wireless microphone
    
  • 1W CW Transmitter
    
  • 433MHz transmitter using SAW resonator
    
  • A 3m (100 MHz) small bug
    
  • Micro Power AM Broadcast Transmitter
    
  • FM Beacon Transmitter (88-108 MHz)
    
  • 1 valve CW transmitter
    
  • 250mW HF CW transmitter
    
  • 2 valve CW transmitter
    
  • Transmitter using LM317
    
  • 5 Watt HF CW transmitter
    
  • Simple FM microphone
    
  • FM bug
    
  • High power FM bug
    
  • 27MHz AM/CW transmitter
    
  • Easy 2-meter transmitter
    
  • QRP HF transmitter
    
  • Spark gap transmitter
    
  • QRP SSB transmitter
    
  • Crystal controlled FM transmitter
    
  • 150mW FM transmitter
    
  • FM transmitter
    
  • 175KHz inductive pulse transmitter (PDF)
    
  • 7MHz QRP transmitter
    
  • Small Radio Transmitter
    
  • FM Telephone Transmitter
    
  • 4 watt FM transmitter
    
  • FM transmitter bug
    
  • Small radio transmitter
    
  • AM transmitter
    
  • 2 Transistor FM Voice Transmitter
    
  • 15 watt FM transmitter
    
  • 4 watt FM transmitter
    
  • Tiny FM transmitter using SMD (surface mount devices)
    
  • Medium range transmitter circuit
    
  • AM FM Simultaneous Transmitter Using Digital IC (CD4001)
    
  • Tracking transmitter
    
  • 5W PLL Transmitter
    
  • Miniature FM transmitter
    
  • Sensitive FM transmitter
    
  • Simple RF transmitter
    
  • 1.5 volt tracking transmitter
    
  • Tracking transmitter
    
  • Micro Power FM Broadcasting Circuits
    
  • Low Power FM Transmitter
    
  • RF/SS Handie Hopper Transmitter Schematic
    
  • Beeper bug transmitter for fox hunt and vehicle tracking
    
  • Guitar FM transmitter
    
  • Very stable RF bug
    
  • Small bug using SMT (surface mount technology)
    
  • Miniature beeper bumper transmitter for vehicle and asset tracking
    
  • Pen bugging device ideal for corporate espionage
    
  • 800 meter (2400ft) range FM transmitter that fits on top of standard 9V battery
    
  • Very stable transmitter than can be carried and move while in use, range is 100-200 meters
    
  • Wireless doorbell for operation on 303MHz, transmit range is around 30 meters (100ft)
    
  • 30-Meter QRP Transmitter for Morse Code
    
  • Miniature FM Transmitter #1
    
  • Miniature FM Transmitter #2
    
  • Miniature FM Transmitter #3
    
  • 4-transistor transmitter
    
  • FM telephone transmitter
    
  • Miniature tracking transmitter
    
  • Light sensing RF transmitter
    
  • 1.5V tracking transmitter
    
  • Micro-Spy with FETs
    
  • Micro-Spy with USW
    
  • Micro-Spy with TTL
    
  • Wireless microphone
    

  Video related schematics

  • Video Clock Superimposer
    
  • Video clock superimposer using PIC16C711
    
  • Simple AV (audio / video) wireless transmitter
    
  • Audio / video distribution amplifier
    
  • 10GHz video link
    
  • 8 x 8 Audio-video switch
    
  • VHF/UHF TV modulator
    
  • LH0032 video amplifier
    
  • LM359N video amplifier
    
  • Driver for multiple VGA monitors
    
  • CCD (charge coupled device) support board
    
  • Closed-Caption Decoder
    
  • PIC-Tock video clock
    
  • RGB video digitizer
    
  • Commodore RF modulator
    
  • Video signal edge enhancement
    
  • Video amplifier
    
  • Decoder for encoded transmissions in Videocrypt and D2MAC
    
  • S-Video to RCA adapter
    
  • VGA to SCART adapter
    
  • Television signal amplifier
    
  • Video signal amplifier circuit
    
  • Video/Audio Wireless Transmitter
    
  • 4 Stage 555 Timer for Video Cam Control
    
  • Digital volt meter with video output
    
  • TV/Radio antenna cable galvanic isolator
    
  • S-video to composite video adapter
    
  • VGA converter for video projectors and fixed frequency monitors
    
  • VGA to TV converter
    
  • VGA to PAL and NTSC converter
    
  • PIC micro frame grabber (TDA8708)
    
  • Commodore 64 Video Modulator 251025 Schematics
    
  • Commodore 64 Video Modulator 251696 Schematics
    
  • TV RGB signal output from a SVGA graphics card
    
  • Macrovision removal
    
  • AVR (AT90S2313) composite PAL colour bar generator
    
  • Motorized Video Camera Mount
    
  • Simple motion detecting camer using PIR (passive infrared)
    
  • Homebuilt video digitizer Mark I
    
  • Homebuilt video digitizer Mark II
    
  • TV transmitter (PDF)