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Alarms and security related schematics

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

Audio power amplifier schematics

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

Audio preamp circuits

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

Automative, car and motorcycle schematics

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

Data acquisition (DAQ) and data logging schematics

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

Filter schematics

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

Games and fun stuff (electronic schematics)

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

Infrared based schematics

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

Laser related power supplies and data transmission

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

LED related schematics

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

Lighting and ligh controller schematics

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

Medical and health related schematics

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

Microcontroller based schematics

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

Misc audio (also see Music, Amplifiers, Preamp)

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

Miscellaneous schematics

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

Model and remote control schematics

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

Motor and general control schematics

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

Music related schematics (also see Audio)

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

PC related schematics

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

PDA interfaces and related schematics

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

Power supplies and control schematics

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

Radio-frequency schematics (also see Transmitters)

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

Solar-power schematics

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

Telephone and intercom related schematics

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

Test equipment circuit diagrams

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

Timing and oscillator circuits

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

Transmitter schematics (also see RF)

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