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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   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)   RETURN TO TOP 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   RETURN TO TOP 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   RETURN TO TOP 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   Digital compass schematic   Temperature datalogger   Serial Port A/D-converter   Centronics port D/A converters and low-pass filter   LCD Thermometer   Wireless Liquid Level Sensing for Restaurant Applications   Accelerometer Schematic   Pressure Sensor-Based Altimeter Circuit   Ultrasonic range finder circuit   1-wire barometer   Water-level sensor   Addressable ADC   Electronic altimeter using PIC16F877   Wireless weater station   RETURN TO TOP 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   RETURN TO TOP Games and fun stuff (schematics) Visor cradle serial interface   Electronic coin tosser   Electronic craps game   First response monitor   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   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   RETURN TO TOP 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   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   RETURN TO TOP Laser related power supplies & 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   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   RETURN TO TOP LED related schematics 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   RETURN TO TOP 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   RETURN TO TOP 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   RETURN TO TOP 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   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   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   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   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)   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   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   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   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 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   RETURN TO TOP 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   RETURN TO TOP Miscellaneous schematics Ultrasonic radar   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   Analog computer   BayComm packet modem   Morse monitor   HamComm modem interface   Morse paddle keyer   UV light box   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   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   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   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)   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   RETURN TO TOP 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   RETURN TO TOP 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   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   RETURN TO TOP 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 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   RETURN TO TOP PC related schematics I2C printer port adaptor   RS232C Level Converter   Isolated Full Duplex RS232C Interface   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   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   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)   RETURN TO TOP 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)   RETURN TO TOP 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   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   RETURN TO TOP Radio-frequency schematics (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   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   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)   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   136 kHz direct conversion receiver   One Watt 2.45 GHz Linear Amplifier   222 MHz Transverter   VFO from 2001 ARRL Handbook, page 17.74   VFO from 2001 ARRL Handbook, page 14.20   Assorted RF circuits   14MHz SSB 10mW Transceiver   Building a Simple LF Exciter   Yaesu band decoder schematic   VLF radio receiver schematic   5 watt, 80 meter QRP CW Transceiver   How to Build a 300MHz AM, RF 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   Radio Control Electric Switch   56K RF Modem   80M ARDF direction finder   RETURN TO TOP 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   RETURN TO TOP 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   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   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   RETURN TO TOP 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)   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   In-circuit electrolytic tester   PIC logic probe with pulser   RETURN TO TOP 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   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)   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   Monostable multivibrator   Clock generator   555 Timer Tutorial + Circuits   Versatile electronic timer   RETURN TO TOP 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   RETURN TO TOP Video related schematics Video Clock Superimposer   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   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/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)