Electronic circuit schematics

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Source from: http://www.district87.org/staff/waltonm/CircuitAnalysis/Electronic%20circuit%20schematics.htm

Alarms and security related schematics Intermittent alarm generator Burglar alarm Moisture alarm Automatic Entry Control System Fridge door alarm Electronic door codelock (PIC16F84) Ultrasonic remote control & alarm system Wire loop alarm Proximity alarm Electronic lock 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 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 Alarm loop sensor (LM3915) Touch triggered alarm Universal alarm system Warning strobe flasher for alarm systems Collection of alarm circuits PIR motion detector light controller Micropower wireless motion detector transmitter Touch activated alarm system Combination Lock (Simple Version) Combination Lock (PIC16F84) Low power RFID transponder Audio power amplifier schematics 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 Amplified ear 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 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 JLH Headphone Amplifiers 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 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 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 Audio preamp circuits mu-stage microphone preamp Solid state microphone preamp Dynamic microphone preamplifier Sound blaster preamplifier Phono preamp Low impedance microphone amplifier Masthead preamp Preamplifier for microphone or guitar use Microphone amplifier RIAA phono amplifier 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 Low impedance microphone amplifier Hi-Fi Preamplifier Crown IC-150A Preamplifier (PDF) Automative, car and motorcycle schematics Race cart or car datalogger Analog Tachometer for Gasoline Engines Headlight On reminder with Light Flashing High Intensity LED 3rd Brake Light Adaptive Windscreen Wiper Control Car clock Car message display Car interval wiper Safety indicator light Speed limit alert Car power supply for MP3 player Car power supply for MP3 player Mk 2.5 Grand Cherokee Off-Highway Lights Engine control unit schematics Portable CD Player Adapter For Car Car battery charger Wireless Auto Tachometer Electronic auto stethoscope Turn signal alarm Motorcycle turn-signal system Cigarette lighter 9V adaptor Alternator Signal Detector Automotive alarm system Road ice alarm Automotive Anti-Lock Brake Control Driver PC based EFI programmer 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 Car burglar alarm Auto to trailer lights interface Car locator (RF based receiver / transmitter) 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 Economy radar detector Combination lock for car liftgate BMW motorcycle side stand protection mod Data acquisition and data logging schematics Datalogger based on 68HC11 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 Air flow detector Air flow detector Strain gauge sensor ADC0804LCN 8-bit A/D converter Web-based thermometer project ADC-x RS232 Interface Schematic (PDF) 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 Network of RS485 temperature sensors Digital compass schematic Temperature datalogger Accelerometer Schematic Serial Port A/D-converter Centronics port D/A converters and low-pass filter LCD Thermometer Wireless Liquid Level Sensing for Restaurant Applications Pressure Sensor-Based Altimeter Circuit Ultrasonic range finder circuit 8-bit analog to digital converter (ADC) Clockless analog to digital converter Low-resolution BCD analog to digital converter AD converter with tracking / sample-hold Analog to digital converter with switching preamplifier Simple flash A/D converter Low-cost A/D converter Logarithmic A/D encoder 1-wire barometer Water-level sensor Addressable ADC Wireless weater station Filter schematics Voltage Controlled State Variable Filter Galaxy Noise Filter RC Notch 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 Single-Supply Sallen Key Notch Filter Single-Supply Twin T Butterworth Low Pass 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 Voltage controlled filter and oscillator "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 Video ping pong game Big Mouth MBC5/CPLD for the GameBoy GameBoy Camera Parallel Port Interface Wireless quiz show system 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 coin tosser Electronic craps game First response monitor Electronic Nicad glow plug driver PowerGlove Interface 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 Applause meter Fart strength meter Model train throttle control DIT shutterglasses controller Furby circuit 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 USB to infrared adapter Infrared remote control shutter release system Infrared transmitter for locomotives IR remote control system for PC IR Receiver (Amplitude Modulated IR) IR Transmitter for Audio (Amplitude Modulated IR) Infrared gate for door Infrared circuits for remote control Serial port controller infrared transmitter (PIC16F628) Digibox interface IR remote control IR remote control jammer Long Range Infrared Remote LCD + IR circuit schematic Infrared body heat detector Stereo IR audio receiver General purpose IR receiver Wireless IR headphone transmitter Wireless IR headphone receiver 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 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 Infrared repeater 40khz IR Tester 555 timer 40khz IR Oscillator IR detector / emitter Fire-Stick infrared remote control Simple infrared remote control Infrared / Ultrasonic beacon Infrared transmitter / decoder Infrared logic probe Implementing Infrared Object Detection Infrared gate detector Infrared relay with relay output IR detector for robotics Computerized Infrared Remote Laser related power supplies and data transmission Laser power supply Laser transmitter/receiver Laser harp Simple laser communicator LASER listening device LASER transmitter / receiver RS-232 Laser Transciever HeNe laser power supply schematics Light beam receiver for laser pistols 12V supply for He-Ne laser Laser diode transmitter 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 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 Diode Laser Power Supplies Ar/Kr Ion Laser Power Supply Design Laser light show Laser light show pattern generator Simple laser communicator LED related schematics Variety of LED circuits Winking LEDs LED flashing light LED initials 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) LED Flasher LED pulser with audible output IR Illuminator Flashing Christmas LED display ICL7660 LED flasher 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 LED Stroboscope - Maintains constant brightness at all flash rates White LED circuits Assorted LED circuits LED Mood Light LED Audio VU Meter Scrolling LED sign 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 Flashing flashlight Flashing road baricade for construction workers Hand clap lamp control 600W 120VAC lamp dimmer 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 Smart 12V light dimmer (PDF) 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 10-channel follower for Austin Hotel 12V Color organ and reverb unit 8-bit digital firing circuit Audio trigger circuit for light chasers Christmas star Electronic candle Electronic candle V2 Fluorescent light dimmer Strobe light LED Mood Light LX-800 Lighting system Xenon Strobe Light Lamp flasher/dimmer Efficient dc lamp dimmer - 74C14 Instrument panel lamp dimmer control Medical and health related schematics Snore alarm electronic device EKG/EEG circuit Radiation Dosage-Rate Meter Heartbeat monitor Cranial Electrotherapy Stimulator Automated crib lights Jogging timer Tan timer Muscular Bio-stimulator Pedometer Heart rate monitor ECG amplifier Simple lie detector Simple lie detector Heartbeat transducer ECG Amplifier 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 PC-based biofeedback monitor Pain field generator 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 Simple RS232C Level Converter using Transistors 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 Atmel 89C Series Flash Microcontroller Programmer AT89C2051 real-time controller PIC12C508 Night-light saver AT89C2051 Night light saver Atmel 8051 Flash Based-Microcontroller Programmer AT89C2051 Digital thermometer and clock PIC16F84 CW decoder (PDF) 12C508 Smart Lock Build a PIC controlled DDS VFO, 0 to 6 MHz PIC controlled DDS VFO, 0 to 6 MHz Basic Stamp Lightning Activity Monitor TCP/IP stack and WWW server in a PIC16F84 PIC16F84 line following robot WWWpic2 - A web server in a PIC PIC16F84 web server 50 MHz frequency counter, voltage meter & SWR/PWR indicator Programmer PIC16F84,12C50x and EEPROM 24Cxx RDS Encoder - digital part PIC programmer for serial port PIC 18 programmer (PIC18F458, PIC18F452, PIC18C252, PIC16C745, PIC18F6620, PIC18F6720) Freign vocabulary recollector 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 POCSAG encoder/decoder Network Time Protocol AVR Clock DS1820 Temperature Sensor Readout Unit PIC16C505 IR / wireless remote control RS485-like multi-drop bus with half duplex serial protocol 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 PIC18 Schematic Atmel AVR programmer Microchip PIC ICSP implementation 101 AT Keyboard to ASCII Decoder using 68HC705J1A MCU DTMF tone decoder using Basic Stamp LCD Serial Terminal Propellor clock (PIC16F84) World's smallest PIC programmer PIC X1 schematic (PIC16F877) 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) Voice recording and message retrieval system 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 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 AT89C2051 line-follower robot Night light saver (PIC12C508) Basic stamp interface circuits PIC16F84 sound controlled Christmas lights 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 PIC16C84 VT-52 Emulator for Linux Microchip PIC ICD (in-circuit debugger) Tony Nixons Pocket Programmer (PIC) PicoWeb V5.1 (AT90S8515) tiny web server 8051 Development System Circuit Board 8051 Development System Circuit Board Temperature controlled based on AT89CX051 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 AC lamp dimmer for Basic Stamp Microcontroller multi channel light dimmer PIC16C63 MIDI controlled light dimmer No parts PIC micro programmer Connecting LED to PIC Micro I/O pins (PDF) Microprocessor RS-232 Reset AT90S8515 experimenter board A PIC-Based Keyboard Emulator PIC-based robot ScanMate audio activated recorded PIC18F252 bootloader schematics Remote control encoder/decoder with PIC16C620 & PIC12C508 Electronic door codelock with PIC16F84 Automatic door opener with PIC12C508 Infra/radio remote control transmitter/receiver with PIC Codelock Automatic door opener (PIC) PIC16F876 Datalogger GPS Repeater Kodak DC-20 camera interface (PIC12C509) Kodak DC-20 camera interface (PIC16F84) Remote control for Raymarine ST4000 Autopilot PIC programmers for parallel port Wisp628 ISP Microchip PIC Programmer 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) Pink noise generator A Schottky-based Saw-to-Tri converter Saw to triangle converter Improved saw to triangle converter Voltage controllable LFO White noise generator Low Frequency Sinewave Generators Horror movies sound effects Sound amplifier Temperature sensitive oscillator 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 Ultrasound detector Electronic siren Two-tone siren Underwater microphone Code practice oscillator Noise generator Electronic whistle 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 NHT subwoofer amp 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 Fender Champ Replica Keyboard scanned 8-tone generator Audio test station Audio tone VU meter Pink noise 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 110 dB beeper - 74C14 Audio output level meter Surround Sound Decoder Mk2 Stereo compressor Audio mixer Miscellaneous schematics Ultrasonic radar How to generate a Rotating Field Chaos generator Simple BFO metal detector Voltage Comparator Information And Circuits Electromagnetic Levitator Build Your Own Digital Setting Circles For Your Astronomical Telescope PL tone generator (NE567) Bat detector Bat detector microphone pre-amplifiers DGPS receiver 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 Full-duplex doorphone with 3 wires connection Analog computer BayComm packet modem Morse monitor HamComm modem interface Morse paddle keyer UV light box Voice activated tape recorder switch 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 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 Vibrating Pocket Bug Detector Basic op-amp circuits 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 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 Griffith Observatory Tesla Coil Fogger smoke machine Dinsmore 1490 digital compass Geiger counter Electric field disturbance monitor Inexpensive seismometer project Digital dial 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 Magnetic levitation circuit PE3342 Programmer Schematic Schmidt Trigger u-Blox GPS receiver board Assorted digital circuits Basic electronic circuits Miscellaneous simple circuits Digital Call Sign Annunciator Ultrasonic switch Sound finding cricket with phase detector Sound finding cricket APRS GPS tracker schematic (PIC16C73) No loss capacitor Discrete logic decimal to BCD converter Doorbell extender Earthquake detector Electromagnetic levitator Jacob's ladder Magnetic ball levitator Photodiode amplifier Relative wind angle indicator Solid-stateTesla coil Very basic circuits Bat detector FCTS Project Smooth Tone Clickless CW Sidetone Generator Morse Code Beacon Keyer Lightning Activated Camera Shutter Trigger Three Power Supplies for the Garmin GPS-20 Sensor Board Driving N-channel FETs from TTL Miniature Self-Powered Autonomous Robot Electronic Dazer 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") Voltage follower with 1G ohm input (LM11) Double-ended flashing voltage monitor - LM10 Full-duplex doorphone Morse code display Intercom schematic Pulse Induction Metal Detector 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 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 Autonomous airplane 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 Two tone train horn 27Mhz toy car receiver 27Mhz toy car transmitter R/C Emergency locator alarm Remote switch for radio-control aircraft accessories Radio Control Battery Backup Glow Plug driver for model engines 12 relay launcher for model rockets Motor and general control schematics Bridge head PWM motor controller Light activated relay Simple 10 Stage Control Box Simple PWM circuit 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 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 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 DC Motor Constant Speed Control 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 H-Bridge shematic DS1821 programmable thermostat SN754410 Dual Motor Driver Board 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 Furnace fan speed controller Remote two-wire stepper motor positioner Drill shaft speed monitor 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 Voice activated switch - MC2830 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) Drum machine Simple MIDI-to-CV converter Sounds effects unit ETI 603 Sequencer Synthesizer schematics 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 MIDI status indicator 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 Audible metronome Visual metronome Vibrato Circuit for Guitar, Steel, Bass, Etc. Zonk Machine and Treble Booster Simple line mixer Simple MIDI tester ASM-1 Analog Synthesizer Module 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 Stereo compressor 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 Analog Input Schematic Kinetic images from sound 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 Isolated Full Duplex RS232C Interface PC Serial Receiver (57.6K Baud / TTL & CMOS) PC Serial Port Receiver Parallel Port Relay Interface PC based 7-segment rolling display DB-9 Connector to DB-25 (both RS-232) Mac Serial Port (RS-422 DIN-8) to RS-232 DB-25 Parallel print capture system ZX96-Mainboard Modem Rockwell RCV336/ACF model V1433VQR ext. Genius Mouse schematics EEPROM programmer Macintosh interface for X10 MR26A Wireless Receiver 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 Commodore 64 24-bit parallel port interface with 8255 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 Serial to ECP interface 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 PC interface for point controller Linux Infra-red Remote Control (LIRC) Homebuilt RS232 LCD Interface Compter microphone 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 CompactFlash to IDE interface ATX power supply schematic X-Y plotter for PC PC based cable tester 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 Simple RS-232 receiver +5v from RS-232 - LM78L05 RS232 - Lowe HF-225 interface 24-bit parallel port interface with 8255 for Commodore computer 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 Tilt sensor for the PalmPilot Casio interface circuits SHARP palm-top/hand-held to RS232 serial converter 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 Interfacing ultrasonic range finder to BrainStem Hamamatsu UVTron Interface to a BrainStem Pulse Shaping on the Palm Pilot Casio interface cable Casio organiser hardware 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 ±12V supply accepts 9 to 30V inputs Power supply provides +5VDC regulated, +10VDC unregulated and 7.5VAC Alkaline battery charger Basic increase in DC voltage 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 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 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 5v Regulated Power Source 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 Automatic Reset Circuit for Astron Power Supply's One-hour battery charger Battery pack capacity indicator Prevision half-wave AC to DC converter Unity gain half-wave rectifier 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 12V to 120VAC inverter Nicad battery cycler Micropower 10ppm/°C, +/-5v reference Battery Characterizer Nicad Battery Discharger/Capacity Indicator 200 Watt Modified PC Power Supply 13.5 Volt 14 Amp Radio-frequency schematics (also see Transmitters) 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 80 Meter CW ARDF receiver CW zero beat indicator (PDF) Build your own VLF Receiver Receiver building blocks Simple wireless radio data link 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 Superregenerative 27MHz receiver 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 No-tune 10GHz transceiver No-tune 1296, 2304 AND 5760MHz transceiver 13cm PSK transceiver for 1.2Mbit/s packet radio Wide-band FM transceiver 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 Phase Shift Radio Direction Finder 23cm Data Transceiver 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 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 DSBSC (Double Side Band Supressed Carrier) GPS (L1) Jammer Frequency Synthesizer Digital Automatic Gain Control (AGC) Four Channel Wireless Transmitter and Receiver Talking receiver 418MHz Control RX/TX PLL synthesizing oscillator (1) PLL synthesizing oscillator (2) PLL synthesizing oscillator (3) 2N2222 40 Meter CW/DSB Transceiver Yaesu FT-736R doppler compensation AM receiver Field strength meter MPF102 receiver MW preamplifier Q - Multiplying Loop Antenna SW aerial amplifier Simple field strength meter 4 band double-tuned preselector UHF Amplifier UHF Preamplifier ZN414 AM receiver ZN414 shortwave receiver 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 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 5 watt, 80 meter QRP CW Transceiver How to Build a 300MHz AM, RF Remote Control System Penncrest 5905 Stereo Receiver Wireless remote control system RF Modem Robotics Project PLL FM transmitter 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 AM/FM/SW active antenna Superregenerative 27MHz receiver RX3302 receiver module schematic 49MHz walkie-talkie Radio Control Electric Switch 56K RF Modem Crossed dipole GPS antenna 80M ARDF direction finder Solar-powered schematics Solar charge controller High efficiency solar powered motor driver Solar robots Solar Tracker 1381 solar engine D1 solar engine FLED solar engine PM1 solar engine Sun tracking circuit for solar arrays Solar power recharger Solar power supply 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 In-Use LED Indicator Telephone In-Use Relay Controller Telephone audio interface 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 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 Cut phone line detector Simple phone tap Telephone auto record Telephone hold button Telephone recorder DTMF tone decoder (Basic Stamp / SSI-202) DTMF Generator/Decoder Telephone recording circuit Interface cables for various cell phones Nokia 3210 MBUS interface 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 Red box detection circuit (PDF) 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 Telephone call director (mini PABX) Phone line sentinel Telephone ring detector Telephone line simulator Cut phone line detector Telephone ring detector - 4N35 Phone-line privacy circuit Telephone autodialler Taxi phone automatic dialler Test equipment schematics Frequency counter Tri-Waveform Generator 50 MHz frequency counter, voltage meter & SWR/PWR indicator 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 220V live wire-in-wall scanner 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) Audible continuity tester Wire tracer Signal generator for signal tracer Electronic level Digital volt meter Adjustable continuity tested 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 1.2GHz frequency counter Simple light sensor adapter for oscilloscope Time Domain Reflectometer (TDR) UTP cable tested 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) Light meter Tonal voltmeter gives audible indication of voltage level AC Millivoltmeter DC millivolt meter Fluxmeter to DVM input XR2206 function generator Low-cost dot/bar generator Milli-ohm adapter Deflection amplifier for oscilloscopes Polarity sensing continuity tester Sensitive RF voltmeter Signal injector 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 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 Beeper to find short circuits 220V wiring detector In-circuit electrolytic tester PIC logic probe with pulser Timing, oscillators etc. (schematics) Budget timer 1 Second Time Base From Crystal Oscillator 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 Time Delay Relay Time Delay Relay Wide-swing Variable Crystal Oscillator Circuit that momentarily closes a pair of contacts at long intervals Long period timer 555 time delay circuit Low frequency clock 4-Bit binary clock 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) Push Button Switch Debouncer Square wave oscillator 5 to 30 Minute Timer NE555 Basic Monostable Mini DDS (Direct Digital Synthesis) Astable Multivibrator AD9852 DDS schematic A GPS receiver based frequency standard Adjustable phase quadrature generator Counter speed doubler Fast rise-time multivibrator Sample-hold controlled oscillator Sine wave oscillator LM3900 sine wave oscillator CMOS 4011 oscillator Simple frequency doubler Sinewave frequency doubler 555 timer circuits Linear voltage to frequency converter Voltage controlled triangle / square generator Monostable multivibrator Clock generator 555 Timer Tutorial + Circuits Frequency comparator - 74HCT74 Clock frequency doubler Versatile electronic timer Transmitter schematics (also see RF) Li'l 7 AM Transmitter Schematic Portable 40W CW transmitter 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 3W FM transmitter FM transmitter (room bug) Microphone Transmitter (bug), 100 MHz Small FM transmitter Wireless microphone XTAL locked tone transmitter AM oscillator for wireless microphones Wireless microphone 1W 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 FM transmitter 4 transistor transmitter FM transmitter Op-amp based FM 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 AM radio tone transmitter - 4049 Op amp based AM radio transmitter 433MHz transmitter using SAW resonator Video related schematics Video Clock Superimposer Simple TV transmitter Audio / video distribution amplifier 10GHz video link Experimental macrovision remover VHF/UHF TV modulator LH0032 video amplifier LM359N video amplifier 8 x 8 Audio-video switch Macrovision code remover 2.3GHz ATV Transmitter 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 Digital video processor MC1374 based TV transmitter TV transmitter Simple TV transmitter Color Bar Generator Microcontroller test pattern generator NTSC Video Distribution Amplifier Commodore RF modulator Video signal edge enhancement Video amplifier Video stabilizer Video/Audio Wireless Transmitter 4 Stage 555 Timer for Video Cam Control Digital volt meter with video output VHF Audio Video Transmitter LH0024 video amplifier Video to RF Modulator Video switcher (PDF) Video switcher 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 Panasonic TR-329B AC-DC Portable TV Homebuilt video digitizer Mark I Homebuilt video digitizer Mark II Audio-video switch TV transmitter (PDF) CCD camera frame grabber