Circuits

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Alarms and security related schematics

  • Proximity alarm  
  • Electronic lock  
  • Electronic door codelock (PIC16F84)  
  • Moisture alarm  
  • Fridge door alarm  
  • Ultrasonic remote control & alarm system  
  • Wire loop alarm  
  • Digital entry lock  
  • Proximity switch  
  • Toxic Gas Detector  
  • Door knob alarm (PDF)  
  • Water seepage alarm (PDF)  
  • Micro-power over temperature alarm (PDF)  
  • Personal silent alarm system  
  • Active IR motion detector  
  • A Basic RF Transmitter for PIR Sensors  
  • PIR motion detector  
  • Simple alarm system  
  • Automatic door opener using PIC12C508  
  • 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  
  • Touch activated alarm system  
  • Combination Lock (PIC16F84)  
  • Low power RFID transponder  

    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  
  • 100W Amplifier  
  • 18W Audio amplifier  
  • 25W MOSFET amplifier  
  • Headphone amplifier  
  • Portable headphone amplifier  
  • 2W amplifier  
  • 4W amplifier  
  • 8 watt audio amp  
  • 20W Amplifier  
  • 50W Amplifier  
  • 100W Audio amplifier  
  • 100W RMS Amplifier  
  • 2-Channel Power Amplifier  
  • 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  
  • Audio amplifier output relay delay  
  • Spatial Distortion Reduction Headphone Amp  
  • HeadBanger Headphone Amp  
  • 2W Amplifier  
  • TDA2030 8 Watt amplifier  
  • Headphone distribution amp  
  • 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  
  • Power amp schematic (PDF)  
  • 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)  
  • 12 Watt Valve Guitar Amp  

    Audio preamp circuits

  • Microphone amplifier  
  • RIAA phono amplifier  
  • Low impedance microphone amplifier  
  • Dynamic microphone preamplifier  
  • Phono preamp  
  • 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  
  • Audio preamp  
  • Electret mic amplifier  
  • Audio preamplifier  
  • Vacuum Tube Microphone Preamp  
  • FET Preamp Cable  
  • Audio preamp  

    Automative, car and motorcycle schematics

  • Electronic auto stethoscope  
  • Turn signal alarm  
  • Motorcycle turn-signal system  
  • Cigarette lighter 9V adaptor  
  • Analog Tachometer for Gasoline Engines  
  • Headlight On reminder with Light  
  • Adaptive Windscreen Wiper Control  
  • Car clock  
  • Car message display  
  • Car interval wiper  
  • Safety indicator light  
  • Speed limit alert  
  • Grand Cherokee Off-Highway Lights  
  • Engine control unit schematics  
  • Portable CD Player Adapter For Car  
  • Car battery charger  
  • Wireless Auto Tachometer  
  • Alternator Signal Detector  
  • Automotive alarm system  
  • Road ice alarm  
  • Automotive Anti-Lock Brake Control Driver  
  • Headlight reminder  
  • Breath Alcohol Tester controlling a car ignition system  
  • Simple car battery charger  
  • Parking sonar  
  • Fuel injector pulse width monitor  
  • BMW R Series Motorcycle Regulator Schematic  
  • 80188XL Engine Tachometer  
  • Integrate Fuel Pump Wire Security Cut Off with a Turbo Timer  
  • Simple Car Preamplifier and Artificial Earth  
  • 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  
  • BMW motorcycle side stand protection mod  

    Data acquisition and data logging schematics

  • Air flow detector  
  • Air flow detector  
  • Strain gauge sensor  
  • Digital Water Wave/Tide/Level Meter (PIC16F876)  
  • 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  
  • Light direction sensor  
  • 12-Bit ADC interface  
  • Digital thermometer  
  • 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  
  • Low Flow-Rate Thermal Flowmeter  
  • Geiger counter  
  • Differential Capacitance Measurement for Tilt Meter  
  • Honey Bee counter (PDF)  
  • Capacitance type liquid level measurement (PDF)  
  • Thermostat node schematic  
  • Digital PC Oscilloscope  
  • Ultrasonic Range & Imager  
  • Precision Digital Altimeter  
  • Digital compass schematic  
  • Temperature datalogger  
  • Serial Port A/D-converter  
  • Centronics port D/A converters and low-pass filter  
  • LCD Thermometer  
  • Acceleration monitor using Analog Devices ADXL202  
  • Optical sensor using PIC12C508  
  • 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  
  • Active 2nd Order Filters  
  • RC Notch Filter (Twin T)  
  • Multiple Feedback Bandpass Filter  
  • CW filters  
  • Self-tune 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  
  • Inversal notch and bandpass filter  
  • DC Accurate, Active RC Lowpass 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  
  • LC filter design  

    Games and fun stuff (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  
  • Mobile robot (PDF)  
  • PSX controler to PC MIDI converter  
  • Dreamcast PC serial adapter  
  • GameBoy Cart Programmer  
  • Memory game  
  • 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  
  • April Fools LEDs  
  • Pinewood Derby logic  
  • Quiz Master  
  • GameBoy Schematic  
  • GameBoy LCD schematic  
  • GameBoy Power & Cartridge schematic  
  • GameBoy ROM+RAM+MBC1 Cart Schematic  
  • GameBoy MBC1 circuit equivalent  
  • Super GameBoy schematic  
  • Quiz show indicator  
  • Dreamcast interface  
  • 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  
  • Video game system using PIC18F252 (direct video generation)  
  • Video game system using SX28 (direct video generation)  
  • DIT shutterglasses controller  
  • Tic-tac-toe game using PIC16F628  
  • Archery timer  
  • 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 remote control shutter release system  
  • Infrared transmitter for locomotives  
  • Infrared gate for door  
  • Infrared circuits for remote control  
  • Serial port controller infrared transmitter (PIC16F628)  
  • IR Receiver (Amplitude Modulated IR)  
  • IR Transmitter for Audio (Amplitude Modulated IR)  
  • Digibox interface  
  • IR remote control  
  • Long Range Infrared Remote  
  • iRDA to TTL interface  
  • 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  
  • Infrared Transmitter and Receiver schematic diagrams  
  • Pyroelectric Infrared Sensor  
  • Minimal Infrared transmitter for PC  
  • Simple IR transmitter circuit  
  • Simple infra-red detector  
  • AVR (AT90S2313) serial port infrared receiver  
  • 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  
  • IR detector for robotics  
  • 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  
  • Laser power supply  
  • Laser transmitter/receiver  
  • Laser harp  
  • Laser Telephone Receiver Circuit  
  • Fiber Optic Voice Communications  
  • Efficient Laser Supply  
  • 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)  
  • Ar/Kr Ion Laser Power Supply  
  • Laser diode power supply circuits  
  • RS-232 Laser Transceiver  
  • HeNe laser power supply  
  • OPT201 Laser receiver  
  • OPT301 Laser receiver  
  • Laser transmitter schematics  
  • Diode Laser Power Supplies  
  • Laser bug circuit  
  • RS-232 Laser Transceiver  
  • Experimental laser data link  
  • Ar/Kr Ion Laser Power Supply Design  
  • Simple laser communicator  

    LED related schematics

  • 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  
  • Color fade  
  • LEDs shimmer randomly as though on fire  
  • LED power supplies for AA cells  
  • 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)  
  • Sequencial LED Flasher with Reversable Direction  
  • Tri Color LED Controller with Serial Interface  
  • 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  
  • 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  
  • LED Mood Light  
  • LED Audio VU Meter  
  • Robot Beacon rotating light using PIC12C508  
  • LM3909 LED flasher  
  • Animated LED signboard (PIC16C84)  
  • Picxie 2 - 8x8 Animated LED Signboard  

    Lighting schematics

  • Garden light switch  
  • DMX lighting and special effects  
  • Microcontroller Multichannel Light Dimmer  
  • Digital timer light switch  
  • Hand clap lamp control  
  • Radio controlled light switch  
  • Disco style Strobe Light  
  • 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  
  • 220V Flashing lights  
  • Coutesy lamp  
  • Bedside lamp timer  
  • TRIAC light dimmer  
  • 12VDC Fluorescent Lamp Driver  
  • Strobe light  
  • Adjustable Strobe Light  
  • RHINO8 EL Sequencer  
  • Light Sequenced Candelabra  
  • Light timer  
  • 5W Fluorescent light intensity modulator (PDF)  
  • 1W Fluorescent lamp night light (PDF)  
  • Low-voltage light dimmer  
  • Light chaser  
  • 4-channel dimmer rack  
  • PIC16F873 light controller  
  • Disco light controller  
  • Neon desklamp  
  • Electronic night light  
  • Neon lamp dimmer  
  • LED Mood Light  
  • LX-800 Lighting system  
  • Xenon Strobe Light  
  • Lamp flasher/dimmer  

    Medical and health related schematics

  • Snore alarm electronic device  
  • Heartbeat transducer  
  • ECG Amplifier  
  • EKG/EEG circuit  
  • Radiation Dosage-Rate Meter  
  • Heartbeat monitor  
  • Cranial Electrotherapy Stimulator  
  • Automated crib lights  
  • Jogging timer  
  • Tan timer  
  • Muscular Bio-stimulator  
  • Pedometer  
  • Simple lie detector  
  • EEG preamp, anti alias filter and isolation circuit  
  • Self Contained Electromyograph (EMG)  
  • Cardiac monitor  
  • Galvanic Skin Response (GSR) Schematic  
  • Brain-Wave Machine  
  • Lie detector  
  • Simple lie detector  
  • ECG project page  
  • The ESP SIM (Sound Impairment Monitor)  
  • 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)  
  • 12C508 Smart Lock  
  • 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  
  • WWWpic2 - A web server in a PIC  
  • PIC16F84 web server  
  • 50 MHz frequency counter, voltage meter & SWR/PWR indicator  
  • Microcontroller board using the Atmel AVR AT90S8535  
  • 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)  
  • Freign vocabulary recollector  
  • Illuminate holiday destinations on a world map  
  • Embedded system to send e-mails (small TCP/IP stack)  
  • Speaking clock using PIC & ISD device  
  • Speaking doorbell using PIC & ISD device  
  • Whistle detector using 8-pin PIC  
  • PIXpand  
  • PIC16F877 to IDE interface  
  • 68HC11 stepper motor control  
  • 90S2313 AVR Robot Board  
  • POCSAG encoder/decoder  
  • Network Time Protocol AVR Clock  
  • DS1820 Temperature Sensor Readout Unit  
  • Rotating Sprocket Wheel Generator (PIC16F84)  
  • Talking PIC - based on SP0256  
  • 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)  
  • Optical sensor using PIC12C508  
  • Interfacing S-7800A to PIC16F877  
  • 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  
  • Voice recording and message retrieval system  
  • Interfacing a GPS to an LCD using a Microcontroller  
  • Long-period watchdog timer  
  • PIC16F84 Range Finder Project  
  • Generate video signals in real-time using a PIC16F84  
  • PIC ICD  
  • 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  
  • 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  
  • 8051 development system circuit board  
  • 8088 maximum mode single board computer (SBC)  
  • Basic 89C2051 / 89C4051 circuit diagram  
  • Debugging dump terminal for 89C2051 designs  
  • Easy debugging terminal  
  • Galvanic decoupling of I2C bus  
  • Circuits interfacing piezo elements to a microcontroller  
  • Driving a TRIAC using a PIC12C508  
  • Isolated RS232C for PIC16F84  
  • Microchip ICD (in-circuit debugger) circuit diagram  
  • Microchip PIC ICSP implementation circuit diagram  
  • Interfacing NMEA GPS to LCD using PIC16F84  
  • PIC ICD (in-circuit debugger)  
  • PIC16C71 morse code callsign generator  
  • PIC16F84 to LCD interface  
  • PIC16F84 I/O expander with PicBasic  
  • Scanning 7-Segment & Keypad  
  • 10-key serial keypad encoder  
  • Simple RS232C Level Converter using Transistors  
  • Talking PIC microcontroller using SP0256  
  • 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  
  • Basic stamp interface circuits  
  • 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  
  • PIC16C84 VT-52 Emulator for Linux  
  • 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  
  • 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  
  • Ser-Key 10-Key Serial Keypad Encoder  
  • 2-wire LCD interface using PIC16CF84  
  • PIC16F84 Serial I/O-expander with PicBasic  
  • RS 485-RPT Schematic  
  • Camera remote control system using Basic Stamp  
  • Low cost Atmel in-system programmer  
  • Ultra low-cost programmer for AT90S family  
  • AVR to USB interface  
  • Programable LCD counter with memory backup based on Atmel AT90S1200A  
  • Connecting AT90S2313 with LCD display 2x16 char and 4x4 keypad  
  • Atmel AVR RCEN fuse bit programmer  
  • 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  
  • AT90S8515 experimenter board  
  • Multi-chip programmer for PIC microcontrollers  
  • Buffered PIC chip interface  
  • A PIC-Based Keyboard Emulator  
  • PIC-based robot  
  • ScanMate audio activated recorded  
  • PIC vacuum fluorescent display interface  
  • PIC18F252 bootloader schematics  
  • PIC16F876 Datalogger  
  • GPS Repeater  
  • Kodak DC-20 camera interface (PIC12C509)  
  • Kodak DC-20 camera interface (PIC16F84)  
  • PIC ICD in-circuit debugger circuit diagram  
  • PIC programmers for parallel port  
  • 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  
  • Audio level indicator  
  • Room noise detector  
  • Amplifier timer  
  • Bell ring generator  
  • Amplified ear  
  • Precision audio millivoltmeter  
  • 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  
  • CMOS IC audio oscillator  
  • Three band Active Tone Control  
  • Automatic gain control (AGC) circuits  
  • Audio frequency meter  
  • Bull Horn  
  • Sound Mixer/Amplifier  
  • Very loud beeper (PDF)  
  • Digital noise generator (PDF)  
  • Tone display system  
  • Tube amplifier  
  • Condenser microphone hookup  
  • Phase shifter  
  • Paradoxical Sound Syntheizer  
  • Various tube crossover circuits  
  • 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  
  • 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  
  • 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  
  • Surround Sound Decoder Mk2  
  • Audio mixer  

    Miscellaneous schematics

  • Ultrasonic radar  
  • 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  
  • Chaos generator  
  • Simple BFO metal detector  
  • Voltage Comparator Information And Circuits  
  • Build Your Own Digital Setting Circles For Your Astronomical Telescope  
  • PL tone generator (NE567)  
  • Bat detector  
  • Bat detector microphone pre-amplifiers  
  • Full-duplex doorphone with 3 wires connection  
  • G Strain energy absorber  
  • RDS Encoder  
  • Toggle Switch Debounced Pushbutton  
  • RDS Encoder  
  • Discrete Set/Reset Flip Flop  
  • Monostable Flip Flops (one shot)  
  • Discrete Bistable Flip Flop  
  • Talking Morse Code Practice Computer  
  • Plant watering watcher  
  • Capacitance sensor  
  • Whistle responder  
  • Nocturnal animals whisker  
  • 12V DC electronic door chime  
  • Biasing Op-Amps into Class A  
  • Parasite zapper  
  • 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  
  • A Visual CW Zero Beating Aid  
  • A two-way Morse practice set  
  • Magnetic levitation device  
  • Tesla power receiver  
  • Lazer Tag Equipment Modifications  
  • Garmin GPS data interconnect  
  • Inexpensive APRS Weather Station  
  • Walking robot  
  • Basic op-amp circuits  
  • Power line FM intercom  
  • Intercom circuit  
  • Lightning Storm Detector  
  • Large LCD Display Buffering Driver  
  • Text to speech converter  
  • 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  
  • 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  
  • Speech recognition using HM2007  
  • GPS receiver 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  
  • Popular Electronics Ultrasound Detector  
  • An Inexpensive X-ray Machine  
  • Navigator 555A radio direction finder (RDF) circuit diagram  
  • Magnetic levitation circuit  
  • PE3342 Programmer Schematic  
  • 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  
  • APRS GPS tracker schematic (PIC16C73)  
  • Common Ground for Older VPW Circuit  
  • Very basic circuits  
  • Bat detector  
  • FCTS Project  
  • Smooth Tone Clickless CW Sidetone Generator  
  • Morse Code Beacon Keyer  
  • Lightning Activated Camera Shutter Trigger  
  • Simple metal detector electronic circuit  
  • Three Power Supplies for the Garmin GPS-20 Sensor Board  
  • Driving N-channel FETs from TTL  
  • Miniature Self-Powered Autonomous Robot  
  • 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  
  • Intercom schematic  
  • Scaling ADXL50 accelerometer output  

    Model and remote control schematics

  • Snake throat muscle controller  
  • Handy cricket for robotic applications  
  • Incline Railway Control Circuit  
  • A Receive Signal Decoder  
  • 27Mhz toy car receiver  
  • 27Mhz toy car transmitter  
  • One ounce rocket ejection timer  
  • LED traffic lights  
  • Two-tone siren  
  • Proportional radio remote control  
  • Alf: The Robotic Matchbox car  
  • Seaplane schematic  
  • Model Rocket with Video Camera  
  • Signal breaking module  
  • RF serial link for robot  
  • PIC based rocket altimeter  
  • 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  
  • Simple charge rate monitor  
  • Deluxe charge rate monitor  
  • "CLONEPAC" memory module for Futaba 8UAF/8UAP  
  • Battery pack discharger  
  • Plane locator  
  • Plane locator 2  
  • Battery low voltage alarm  
  • Battery low voltage alarm 2  
  • Ultimate battery low voltage alarm  
  • 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  
  • Spider robot electronic project page  
  • Two tone train horn  
  • R/C Emergency locator alarm  
  • Remote switch for radio-control aircraft accessories  
  • 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  
  • Motor speed controllers  
  • Ceiling fan speed control  
  • Delayed off light switch  
  • Deoderizer fan timer  
  • 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  
  • Pump controller  
  • H-Bridge motor controller (5 amps, 100 watts)  
  • Dual Channel Servo Pulse to H-Bridge Interface  
  • Servo pulse to PWM converter  
  • 12V Sump Pump Control  
  • Rolling code 4-channel UHF remote control  
  • DC Motor Speed Controller  
  • 3 Phase Brushless DC Motor Xtal Based Controller  
  • DC motor controller  
  • Garden moisture controller  
  • Overload Voltage Protection with Automatic Reset  
  • Pulse Width Modulator  
  • Pulse Width Modulator Motor Speed 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)  
  • AC switching with TRIAC from TTL  
  • Control 120VAC relay with TTL  
  • Driving a relay with a CPU  
  • Power-line Appliance Controller  
  • Simple Switched Servo Driver  
  • Combination-controlled, fully customizable RF remote control  
  • Thermoelectic controller (scriptable thermometer)  
  • Stepper motor positioner  
  • Stepper motor driver  
  • Thermostat  
  • Frequency switch  
  • PIC16F84 RF remote controller  
  • Stepper motor 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  
  • PWM Motor Speed Controller / DC Light Dimmer  
  • Constant Temperature Circuit  
  • PWM DC Motor Speed Control  
  • Solenoid starter  
  • CO2 controller for planted tanks  
  • Light activated relay  
  • Delayed shutter control for Kodak DC-20  
  • Gasoline generator automatic throttle controller  
  • Block power switching module  
  • 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  
  • Colour organ light  
  • MP3 Player  
  • Metronome and pitch generator  
  • Mini metronome  
  • Compact Flash / IDE MP3 Player MKI  
  • 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  
  • Vibrato Circuit for Guitar, Steel, Bass, Etc.  
  • MIDI status indicator  
  • 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  
  • 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  
  • EEPROM programmer  
  • Commodore 64 24-bit parallel port interface with 8255  
  • Sound Card Interface with Tone Keyer  
  • RGB oo Monochrome converter - Matches impedance of PC to CCTV monitor  
  • Ericsson phone to PC serial port interface  
  • PC serial port receiver  
  • Parallel port relay interface  
  • ISA 48 I/O digital card  
  • PC infrared iRDA interface using TFDS 4500  
  • Jupiter card programmer  
  • USB to RS232 Dongle  
  • Parallel (Printer) Port Interface  
  • RS-232 line monitor and loopback cables  
  • The KD2BD Pacsat Modem  
  • 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  
  • A PC-Based LowFER Frequency Synthesizer  
  • General purpose 48-bit ISA parallel I/O card  
  • Power from RS-232 port  
  • PCI to ISA converter  
  • WatchDog for ISA Bus  
  • 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  
  • 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  
  • Interfacing to an IBM PC/AT keyboard  
  • PC interface for point controller  
  • Linux Infra-red Remote Control (LIRC)  
  • Homebuilt RS232 LCD Interface  
  • 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  
  • IDE hard-disk interface for Amiga 500  
  • How to construct Garmin GPS receiver interface cables  
  • iRDA printer adapter  
  • 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

  • Casio interface circuits  
  • SHARP palm-top/hand-held to RS232 serial converter  
  • Interfacing ultrasonic range finder to BrainStem  
  • Hamamatsu UVTron Interface to a BrainStem  
  • Casio interface cable  
  • Casio organiser hardware  
  • MIDI interface for Palm computers  
  • MIDI interface for Palm cradle  
  • MIDI interface for Visor USB  
  • MIDI-USB Cradle for Visor (Deluxe, Platinum)  
  • MIDI interface for Visor  
  • 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  
  • 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  
  • Alternative power source for Magellan GPS receivers  
  • Power Tool Torque Control  
  • 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  
  • Variable DC power supply  
  • 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  
  • 1A Variable Regulated Power Supply  
  • Negative voltage generator  
  • 12V battery capacity tester  
  • NE555 Low Voltage Battery Disconnect Circuit  
  • 33 Volt DC To DC Converter  
  • Automatic AC voltage (110/240) selector  
  • Variable 0-5A Current Source  
  • Ground Fault Interupter  
  • Intelligent battery charger  
  • 12 Volt DC Load Control and Battery Protection  
  • Low battery indicator  
  • Variable power supply  
  • Switching Power Supply  
  • Low Power DC Quadrupler  
  • Surge protector  
  • Ultimate power supply  
  • Variable Regulated Power Supply  
  • 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  
  • High current regulated power supply  
  • One 9V battery gives +18, +25, +33V  
  • +9V *and* -9V from one battery  
  • Battery charger  
  • Adjustable power supply using LM317  
  • Simple +5V power supply circuit  
  • 12 Vdc - 120 Vac Inverter Schematic  
  • +12V/-12V Power supply unit  
  • +/-12V -> +/-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 Motor Speed Controller / DC Light Dimmer  
  • PWM Motor/Light Controller  
  • Low Power LED Voltmeter  
  • 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  
  • Battery Charger Ideas  
  • Power control for arc welders and other inductive loads  
  • Charger for gel lead acid batteries  
  • Nicad battery cycler  
  • 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  
  • TRF AM Receiver circuit  
  • 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  
  • CW zero beat indicator (PDF)  
  • Build your own VLF Receiver  
  • 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  
  • 2MHz RF Oscillator  
  • 50-150MHz Overtone Oscillator  
  • 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  
  • Car radio tunes the Amateur Bands  
  • Crystal set that requires no antenna  
  • 80m Direct Conversion Receiver  
  • A compact L-match ATU for portable use  
  • Morse Adaptor for your VHF/UHF FM rig  
  • An end-fed antenna, L-match coupler and resistive bridge for HF  
  • AM Broadcast Band Regenerative Receiver  
  • 50 MHz to 146 MHz Converter  
  • Hear Amateurs on your Shortwave Radio!  
  • Compact 20 14 MHz direct conversion receiver  
  • Hear Amateurs on your FM Radio!  
  • RF actuated CW monitor  
  • LF to HF Converter  
  • Super 80 ultra-simple SSB receiver for 3.5 MHz  
  • Class B series modulator  
  • L-Band PHEMT LNA for GPS, Inmarsat etc  
  • Advanced VHF power meter  
  • The MRX-40 Mini Receiver  
  • 23cm Data Transceiver  
  • External antenna for the GPS-38, Magellan 2000, or Eagle Explorer GPS receivers  
  • AM Broadcast Band Active Antenna  
  • Active antenna with gain  
  • Ham Band VFO  
  • HF Signal generator  
  • Simple AM Radio Receiver & Amplifier  
  • Bug detector  
  • 175KHz inductive pulse receiver (PDF)  
  • 200-400 MHz voltage controlled oscillator  
  • AM/FM/SW active antenna  
  • RF Sniffer <.5 to >500 MHz  
  • Demodulator Schematic/Design  
  • AM BCB radio receiver  
  • Regenerative shortwave receiver  
  • 7MHz SSB Transceiver  
  • DSBSC (Double Side Band Supressed Carrier)  
  • Frequency Synthesizer  
  • Digital Automatic Gain Control (AGC)  
  • Four Channel Wireless Transmitter and Receiver  
  • Talking receiver  
  • 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  
  • 23cm Wide-Band FM data transceiver for high-speed packet-radio  
  • VLF radio receiver schematic  
  • 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  
  • 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  

    Solar-powered schematics

  • Sun tracking circuit for solar arrays  
  • Solar power recharger  
  • Solar power supply  
  • Solar charge controller  
  • Solar robots  
  • 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  
  • Solar Panel Charge Controller / Low Voltage Disconnect Circuit  
  • Solar Panel Current Meter  
  • SCC2 10 Amp Solar Charge Controller  
  • Solar Charged LED Flashlight  
  • AA battery solar charger  
  • Solar Panel Charge Controller / Low Voltage Disconnect Circuit  
  • Solar Panel Current Meter  
  • 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  
  • DTMF Generator/Decoder  
  • Interface cables for various cell phones  
  • Telephone music on hold box  
  • Telephone ring controlled relay  
  • 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  
  • FM telephone bug  
  • Universal telephone hold  
  • Talking phone dial monitor  
  • 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  
  • Phone ring circuit schematic  
  • Cut phone line detector  
  • Telephone autodialler  
  • Taxi phone automatic dialler  

    Test equipment schematics

  • Audible continuity tester  
  • Wire tracer  
  • Signal generator for signal tracer  
  • Electronic level  
  • Digital volt meter  
  • Adjustable continuity tested  
  • Frequency counter  
  • Tri-Waveform Generator  
  • 220V live wire-in-wall scanner  
  • Owens Bridge Inductance Measurement Device  
  • ESR Meter  
  • Line Output / Flyback transformer tester  
  • PC-Based Digital Storage Oscilloscope (DSOA)  
  • PC Based Digital Storage Oscilloscope Mk3  
  • Simple 6-Digit 40MHz Frequency Counter Module  
  • Automatic stud detector  
  • Capacitance meter  
  • Capacitance meter  
  • AC Line Current Detector  
  • Triangle and Squarewave Generator  
  • Signal tracer / injector  
  • Voltage probe  
  • Live line detector  
  • Grid dip meter  
  • PCB VSWR bridge  
  • Electric field & leakage detector  
  • Simple polarity detector  
  • RCM710 Electronic Scale  
  • 3 - 12 MHz Signal Generator  
  • Some simple test equipment to build  
  • RF Power Meter for the QRPer  
  • Dip Oscillator for HF  
  • Two Tone Audio Oscillator (use for SSB tests)  
  • Simple pH meter  
  • Temperature compensated pH meter  
  • pH meter with calibration  
  • Four Channel Oscilloscope Adapter  
  • Arbitrary Waveform Generator  
  • Digital Pressure Gauge  
  • Remote Field Strength Meter  
  • Digital frequency counter  
  • Function generator  
  • High / Low indicator  
  • AC/DC LED Indicator  
  • Micro ohm meter  
  • Micro volt probe  
  • MOSFET tester  
  • Power factor meter  
  • Ramp generator  
  • LASER/LED light output intensity meter (PDF)  
  • Frequency and capacitance meter  
  • Resistor decade box  
  • Simple light sensor adapter for oscilloscope  
  • Time Domain Reflectometer (TDR)  
  • 40MHz frequency counter using Atemel AVR 2312 microcontroller  
  • pH Meter  
  • Multi Wire Cable Tester  
  • Connection tester  
  • EMF field probe  
  • Function generator  
  • Logic probe  
  • Zener diode tester  
  • Mini DDS (direct digital synthesizer)  
  • LCD frequency counter (PIC16F84)  
  • 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  
  • 120MHz frequency counter  
  • Capacitance meter that connects to multimeter  
  • Transistor tester and signal injector  
  • Continuity tester  
  • Square wave oscillator (555)  
  • 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  
  • 4-channel DSO for oscilloscope  
  • Field strength meter for the 137 kHz band  
  • In-circuit electrolytic tester  
  • PIC logic probe with pulser  

    Timing, oscillators etc. (schematics)

  • Budget timer  
  • Long period timer  
  • 555 time delay circuit  
  • Low frequency clock  
  • Countdown timer with relay  
  • DDS using AD9835  
  • 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  
  • 1KHz Sinewave generator  
  • Timed beeper  
  • GPS receiver clock circuit  
  • Time Delay Relay  
  • Time Delay Relay  
  • Wide-swing Variable Crystal Oscillator  
  • Circuit that momentarily closes a pair of contacts at long intervals  
  • Onboard Fogger Timer  
  • Colpitts 1 to 20 MHz Crystal Oscillator  
  • Divide By 1-1/2 Circuit  
  • Simple sinewave generator  
  • Two Transistor Sine Wave Oscillator  
  • 10 Hz to 10 Khz VCO with Square and Triangle wave  
  • 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  
  • 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)  
  • Timer based on Microchip PIC16F628  
  • 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  
  • Monostable multivibrator  
  • Clock generator  
  • 555 Timer Tutorial + Circuits  
  • Versatile electronic timer  

    Transmitter schematics (also see RF)

  • Li'l 7 AM Transmitter Schematic  
  • 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  
  • Basic FM Transmitter  
  • 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  
  • Two Valve 40m CW Transmitter  
  • Frequency agile 80m CW QRP transmitter  
  • 80 metre DSB transmitter  
  • One Valve CW transmitter  
  • Simple Low FER Transmitter  
  • 7Mhz AM/CW Amateur Radio Transmitter  
  • VHF FM transmitter  
  • Simple FM transmitter  
  • Wireless microphone  
  • Shortwave radio transmitter  
  • 175KHz inductive pulse transmitter (PDF)  
  • 7MHz QRP transmitter  
  • Small Radio Transmitter  
  • FM Telephone Transmitter  
  • 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  
  • 30-Meter QRP Transmitter for Morse Code  
  • Miniature FM Transmitter #1  
  • Miniature FM Transmitter #2  
  • Miniature FM Transmitter #3  
  • Light sensing RF transmitter  
  • Micro-Spy with FETs  
  • Micro-Spy with USW  
  • Micro-Spy with TTL  

    Video related schematics

  • Video Clock Superimposer  
  • Video clock superimposer using PIC16C711  
  • Simple AV (audio / video) wireless transmitter  
  • Audio / video distribution amplifier  
  • 10GHz video link  
  • Experimental macrovision remover  
  • 8 x 8 Audio-video switch  
  • VHF/UHF TV modulator  
  • LH0032 video amplifier  
  • LM359N video amplifier  
  • Macrovision code remover  
  • Driver for multiple VGA monitors  
  • CCD (charge coupled device) support board  
  • Closed-Caption Decoder  
  • PIC-Tock video clock  
  • Video/Audio Wireless Transmitter  
  • Video signal amplifier  
  • RGB video digitizer  
  • Color Bar Generator  
  • Microcontroller test pattern generator  
  • NTSC Video Distribution Amplifier  
  • Commodore RF modulator  
  • Video signal edge enhancement  
  • Video amplifier  
  • 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)  
  • Low cost audio/video modulator and transmitter  
  • Many video amplifier circuits includiing transmission over UTP (PDF)  
  • 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  
  • Homebuilt video digitizer Mark I  
  • Homebuilt video digitizer Mark II  
  • TV transmitter (PDF)