Alarms and security related schematics

• Proximity alarm
  
• Electronic lock
  
• Intermittent alarm generator
  
• Burglar alarm
  
• Electronic door codelock (PIC16F84)
  
• Moisture alarm
  
• Automatic Entry Control System
  
• Fridge door alarm
  
• Ultrasonic remote control & alarm system
  
• Wire loop alarm
  
• Digital entry lock
  
• Proximity switch
  
• Toxic Gas Detector
  
• Door knob alarm (PDF)
  
• Water seepage alarm (PDF)
  
• Micro-power over temperature alarm (PDF)
  
• Personal silent alarm system
  
• Active IR motion detector
  
• A Basic RF Transmitter for PIR Sensors
  
• PIR motion detector
  
• Simple alarm system
  
• 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

• 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
  
• Amplified ear
  
• 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

• Microphone amplifier
  
• RIAA phono amplifier
  
• Low impedance microphone amplifier
  
• mu-stage microphone preamp
  
• Solid state microphone preamp
  
• Dynamic microphone preamplifier
  
• Sound blaster 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
  
• Hi-Fi Preamplifier
  
• Crown IC-150A Preamplifier (PDF)
  

  Automative, car and motorcycle schematics

• Electronic auto stethoscope
  
• Turn signal alarm
  
• Motorcycle turn-signal system
  
• Cigarette lighter 9V adaptor
  
• 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
  
• 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

• Air flow detector
  
• Air flow detector
  
• Strain gauge sensor
  
• 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
  
• 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
  
• Electronic coin tosser
  
• Electronic craps game
  
• First response monitor
  
• 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 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
  
• Infrared body heat detector
  
• Stereo IR audio receiver
  
• General purpose IR receiver
  
• Wireless IR headphone transmitter
  
• Wireless IR headphone receiver
  
• USB to infrared adapter
  
• 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 remote control system for PC
  
• IR Receiver (Amplitude Modulated IR)
  
• IR Transmitter for Audio (Amplitude Modulated IR)
  
• Digibox interface
  
• IR remote control
  
• IR remote control jammer
  
• Long Range Infrared Remote
  
• LCD + IR circuit schematic
  
• 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
  
• IR detector for robotics
  
• Computerized Infrared Remote
  

  Laser related power supplies and data transmission

• Light beam receiver for laser pistols
  
• 12V supply for He-Ne laser
  
• Laser diode transmitter
  
• Laser power supply
  
• Laser transmitter/receiver
  
• Laser harp
  
• Simple laser communicator
  
• LASER listening device
  
• LASER transmitter / receiver
  
• RS-232 Laser Transciever
  
• HeNe laser power supply schematics
  
• 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

• LED Flasher
  
• LED pulser with audible output
  
• IR Illuminator
  
• Flashing Christmas LED display
  
• ICL7660 LED flasher
  
• 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)
  
• 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
  
• 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
  
• Heart rate monitor
  
• ECG amplifier
  
• Simple lie detector
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• Electronic siren
  
• Two-tone siren
  
• Underwater microphone
  
• Code practice oscillator
  
• Noise generator
  
• Electronic whistle
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• Commodore 64 24-bit parallel port interface with 8255
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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
  
• 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)

• 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
  
• 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
  
• 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
  
• 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
  
• Radio Control Electric Switch
  
• 56K RF Modem
  
• Crossed dipole GPS antenna
  
• 80M ARDF direction finder
  

  Solar-powered schematics

• Sun tracking circuit for solar arrays
  
• Solar power recharger
  
• Solar power supply
  
• 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
  
• Solar car array controller schematic
  
• Solar car battery monitor schematic
  
• Solar car brake controller schematic
  
• Solar car main controller schematic
  
• Solar car display controller schematic
  
• Solar car electrical design and circuit index
  
• Portable solar battery charger
  
• Sensor Electronic Tracker with H-Bridge Drive
  
• Sensor Electronic Tracker with Simple Solar Charge Controller
  
• Solar tracking control system
  
• LED7 solar tracker
  
• Solar step-down regulator
  
• Zener-based solar engine
  
• AA battery solar charger
  
• AA battery solar charger
  
• Solar Panel Charge Controller / Low Voltage Disconnect Circuit
  
• Solar Panel Current Meter
  
• SCC2 10 Amp Solar Charge Controller
  
• Solar Charged LED Flashlight
  
• AA battery solar charger
  
• Solar Panel Charge Controller / Low Voltage Disconnect Circuit
  
• Solar Panel Current Meter
  
• Solar cell Nicad charger
  
• Solar powered dock lamp flasher
  

  Telephone and intercom related schematics

• Telephone recording circuit
  
• 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
  
• 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

• 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
  
• 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
  
• 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
  
• 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
  
• In-circuit electrolytic tester
  
• PIC logic probe with pulser
  

  Timing, oscillators etc. (schematics)

• Budget timer
  
• Long period timer
  
• 555 time delay circuit
  
• Low frequency clock
  
• 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
  
• 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
  
• Wireless microphone
  
• XTAL locked tone transmitter
  
• AM oscillator for wireless microphones
  
• Wireless microphone
  
• 1W CW Transmitter
  
• 433MHz transmitter using SAW resonator
  
• 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
  
• 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
  

  Video related schematics

• Video Clock Superimposer
  
• Simple TV 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
  
• 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
  
• TV transmitter (PDF)
  
• CCD camera frame grabber