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DIVERSE ALARMS

• Intermittent alarm generator
• Burglar alarm
• Moisture alarm
• Proximity alarm
• Electronic lock
• Door knob alarm (PDF)
• Water seepage alarm (PDF)
• Micro-power over temperature alarm (PDF)
• 5 Zone alarm circuit
• Miniature loop alarm
• Gate alarm circuit
• Perimeter monitor
• Digital combination lock
• Touch activated alarm system

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LIGTHING

• 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
• Disco style Strobe Light
• 220V Flashing lights
• Coutesy lamp
• Bedside lamp timer
• TRIAC light dimmer
• 12VDC Fluorescent Lamp Driver
• Strobe light
• Adjustable Strobe Light
• 5W Fluorescent light intensity modulator (PDF)
• 1W Fluorescent lamp night light (PDF)
• Electronic night light
• LED Mood Light
• LX-800 Lighting system
• Xenon Strobe Light
• Lamp flasher/dimmer
• PWM light bulb regulator

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MEDICAL TESTER

• Radiation Dosage-Rate Meter
• Cranial Electrotherapy Stimulator
• Automated crib lights
• Joigging timer
• Tan timer
• Muscular Bio-stimulator
• Pedometer
• Simple lie detector
• Heartbeat transducer
• ECG Amplifier
• The ESP SIM (Sound Impairment Monitor)

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FOR AUDIO

• Frequency shifter
• A Schottky-based Saw-to-Tri converter
• Saw to triangle converter
• Improved saw to triangle converter
• Voltage controllable LFO
• White noise generator
• Low Power Op-Amp - Audio Amp (Intercom)
• 555 Tone Generator (8 Ohm Speaker)
• 3 Transistor Audio Amp (50 milliwatt)
• Low Frequency Sinewave Generator
• Horror movies sound effects
• Sound amplifier
• Temperature sensitive oscillator
• Old-fashioned siren effect
• Simple VOX circuit
• Audio mixer circuits
• Audio oscillator circuits
• Simple 4-watt AF amplifer
• A self-tuning AF filter for CW
• SSB AF Filter
• Audio level indicator
• Room noise detector
• Amplifier timer
• Bell ring generator
• Amplified ear
• Precision audio millivoltmeter
• Voice record/playback using ISD 1000A
• Audio Graphic Equaliser
• FET audio mixer
• Microphone mixer
• Tone control
• Digital volume control
• Sound level meter
• CMOS IC audio oscillator
• Electronic siren
• Two-tone siren
• Underwater microphone
• Code practice oscillator
• Noise generator
• Electronic whistle
• Very loud beeper (PDF)
• Digital noise generator (PDF)
• Condenser microphone hookup
• Phase shifter
• Paradoxical Sound Syntheizer
• 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
• 3-Band equalizer
• 6-Input mixer
• Doorphone intercom
• Stereo line driver
• Audio notch filer
• Peak reading audio level meter
• Tone control
• Electronic canary
• Improved PL tone decoder
• Magnetic cartridge amplifier
• LM358 preamp
• Sound detector
• Tone detector
• Tone generator
• Warbler
• Voltage Controlled Panner
• Low Noise Microphone Preamplifier
• Bridging Adapter For Power Amplifiers
• Simple Surround Sound Decoder
• Simplest Ever Amplifier Bridging
• Stereo Width Controllers
• Power Amplifier Clipping Indicator
• Phono Preamps For All
• Digital Delay Unit For Surround Sound
• Parametric And Sub-Woofer Equaliser
• High Quality Sound Mixer
• Loudspeaker Protection and Muting
• Direct Injection Box for Recording & PA Systems
• Minimalist Discrete Hi-Fi Preamp
• Signal Detecting Auto Power-On Unit
• Load Sensing Automatic Switch
• Amplifier thermal protection
• Active Sub-Woofer and Controller
• Balanced Line Driver & Receiver
• VU And PPM Audio Metering
• Variable Amplifier Impedance
• Linkwitz Cosine Burst Generator
• Low Noise Balanced Microphone Preamp
• Fast Audio Peak Limiter
• Subwoofer Equaliser

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MISCELLANEOUS SCHEMATICS

• Discrete Set/Reset Flip Flop
• Monostable Flip Flops (one shot)
• Discrete Bistable Flip Flop
• Chaos generator
• Simple BFO metal detector
• Build Your Own Digital Setting Circles For Your Astronomical Telescope
• Electric field disturbance monitor
• CW Practice/transmission monitor
• A simple CW keyer for paddle keys
• Plant watering watcher
• Capacitance sensor
• Whistle responder
• Nocturnal animals whisker
• 12V DC electronic door chime
• Random noise generator
• Hardware random bit generator
• Fantastic Atom Expander
• Black Light
• Computerize Your Room/Home
• Flash slave trigger
• A Visual CW Zero Beating Aid
• A two-way Morse practice set
• Basic op-amp circuits
• Electronic fish lure
• Ultrasonic sound receiver
• Experimental data transmitter for fiber optics
• Experimental fiber optic receiver
• Ion detector
• Darkness monitor
• Electroscope
• Simple event counter
• Geiger counter
• Light detector
• Short-circuit beeper
• LM 1800 FM stereo decoder
• Glitch detector
• MAX924 bar-graph level gauge
• Ultrasonic

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MODEL

• LED traffic lights
• R/C Receiver <-> Joystick Port Interface for Flight Simulators
• Proportional Radio Control of models
• Two-tone siren
• HEXBOT robot
• Alf: The Robotic Matchbox car
• PICar
• A Low Cost Thermal Peak Detection Charger
• A Miniature High-Rate Speed Control with Brake
• An On/Off Motor Control with Brake
• 0-10V control for RC servos
• 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
• Two tone train horn
• Radio Control Battery Backup
• Glow Plug driver for model engines

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MOTOR , RELAY

• 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
• Light/dark detector
• Pulse Width Modulation DC Motor Control
• Stepper motor controller
• Touch switch
• 12V Sump Pump Control
• Transistor relay driver
• Latching relay driver
• Relay delay circuit
• Touch switch
• Low voltage DC motor speed controller
• Flashing neon christmas lights
• Three input first response monitor
• Switch-on delay circuit
• Electronic thermostat
• LM3911 temperature controller
• Programmable light-activated relay
• 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
• Stepper motor positioner
• SN754410 Dual Motor Driver Board
• Temperature monitor
• Cold activated switch
• Voltage comparator switch
• Dark activated switch
• DC Push Button Motor Control Circuit
• Light detector
• Sound operated switch
• Touch Switches
• Detect fan failure with a single transistor
• Constant Temperature Circuit
• PWM DC Motor Speed Control
• Solenoid starter
• CO2 controller for planted tanks
• Light activated relay

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MUSIC

• Drum machine
• Simple MIDI-to-CV converter
• Sounds effects unit
• ETI 603 Sequencer
• Synthesizer schematics
• Peak-reading meters
• Octave screamer
• Optical Theremin - electronic musical instrument
• Spring reverb unit
• Metronome and pitch generator
• Mini metronome
• Simple colour organ
• Guitar fuzz effect
• 8 note tune player
• Colour (Sound) Organ
• Transistor organ
• Audible metronome
• Visual metronome
• Simple line mixer
• Simple MIDI tester
• Electronic metronome
• 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
• D.C. Mixer for music synthesizers
• Opto-isolated MIDI cable

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ORGANIZER DATA

• SHARP palm-top/hand-held to RS232 serial converter
• Casio organiser hardware

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TELEPHONE

• 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
• Phone in use circuit
• Digisound ring modulator
• Incoming call indicator
• Ringing Phone Light Flasher
• Phone Busy Indicator
• FM Telephone Bug
• Cut Phone Line Detector
• Simple Phone Tap
• Telephone Hold Button
• Telephone Recorder
• Telephone recording circuit
• 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
• Universal telephone hold
• Talking phone dial monitor
• Telephone line simulator
• Telephone privacy adapter
• Telephone ringing circuits
• Simple circuit to connect telephone equipment to audio mixer
• Hands-free telephone
• Using old phones as an intercom
• Phone line to audio
• Phone recorder
• Telephone tap
• Telephone controlled night light

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TESTER EQUIPMENT

• AC Line Current Detector
• Triangle and Squarewave Generator
• Tri-Waveform Generator
• JFET crystal testing oscillator
• Grid Dip Oscillator circuit and how to use it
• Voltage probe
• Live line detector
• Simple polarity detector
• RCM710 Electronic Scale
• 3 - 12 MHz Signal Generator
• Some simple test equipment to build
• RF Power Meter for the QRPer
• Dip Oscillator for HF
• Two Tone Audio Oscillator (use for SSB tests)
• Audible continuity tester
• Wire tracer
• Signal generator for signal tracer
• Electronic level
• Digital volt meter
• Adjustable continuity tested
• LASER/LED light output intensity meter (PDF)
• Frequency and capacitance meter
• Simple light sensor adapter for oscilloscope
• Time Domain Reflectometer (TDR)
• EMF field probe
• Function generator
• Logic probe
• Zener diode tester
• 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
• Build a Magnetic Field Immunity Tester
• 555 Timer IC Tester
• Continuity tester 2
• Continuity tester
• Logic probe
• 220V wiring detector

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TIMING

• 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
• Staircase wave generator
• 1KHz Sinewave generator
• Timed beeper
• Weign Bridge generator
• Time Delay Relay
• Time Delay Relay
• Wide-swing Variable Crystal Oscillator
• Circuit that momentarily closes a pair of contacts at long intervals
• Long period timer
• 555 time delay circuit
• Low frequency clock
• 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
• Micropower pulse generator (PDF)
• Push Button Switch Debouncer
• Square wave oscillator
• Clock generator
• 555 Timer Tutorial + Circuits

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VIDEO

• Audio / video distribution amplifier
• Driver for multiple VGA monitors
• Closed-Caption Decoder
• PIC-Tock video clock
• Video signal amplifier
• MC1374 based TV transmitter
• TV transmitter
• Simple TV transmitter
• Video signal edge enhancement
• Video amplifier
• 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
• Do-it-Yourself VGA ro PPrPb Cable
• Many video amplifier circuits includiing transmission over UTP (PDF)
• Mark II video digitiser
• Video digitiser
• Audio-video switch






AUDIO FILTERS

• Active 2nd Order Filters
• RC Notch Filter (Twin T)
• 3KHz low-pass filter plus audio amp (PDF)
• "A" Weighting Filter For Audio Measurements
• Multiple Feedback Bandpass Filter
• Akerberg-Mossberg (AM) Second Order Bandpass inverting
• Deliyannis Second Order Bandpass I inverting
• Deliyannis Second Order Bandpass II inverting
• KHN (Non-Inverting Input) Second Order Bandpass inverting
• Multiple Feedback (MFB) Second Order Bandpass I inverting
• Multiple Feedback (MFB) Second Order Bandpass II inverting
• Tow-Thomas (TT) Second Order Bandpass inverting
• Twin-T Second Order Bandpass inverting
• Berka-Herpy (BH) Second Order Bandpass non-inverting
• Fliege Second Order Bandpass non-inverting
• KHN (Inverting Input) Second Order Bandpass non-inverting
• Mikhael-Bhattacharyya (MB) Second Order Bandpass non-inverting
• Sallen-Key (SK) Second Order Bandpass non-inverting
• Akerberg-Mossberg (AM) Second Order Notch inverting
• KHN (Non-Inverting Input) Second Order Notch inverting
• Berka-Herpy (BH) Second Order Notch non-inverting
• Fliege Second Order Notch non-inverting
• KHN (Non-Inverting Input) Second Order Notch inverting
• Mikhael-Bhattacharyya (MB) Second Order Notch non-inverting
• Sallen-Key (SK) Second Order Notch non-inverting
• Twin-T Second Order Notch I non-inverting
• Twin-T Second Order Notch II non-inverting
• First Order Highpass III inverting
• First Order Highpass IV inverting
• First Order Highpass I non-inverting
• First Order Highpass II non-inverting
• Akerberg-Mossberg (AM) Second Order Highpass inverting
• KHN (Inverting Input) Second Order Highpass inverting
• Multiple Feedback (MFB) Second Order Highpass inverting
• Berka-Herpy (BH) Second Order Highpass non-inverting
• Fliege Second Order Highpass non-inverting
• KHN (Non-Inverting Input) Second Order Highpass non-inverting
• Mikhael-Bhattacharyya (MB) Second Order Highpass non-inverting
• Sallen-Key (SK) Second Order Highpass I non-inverting
• Sallen-Key (SK) Second Order Highpass II non-inverting
• Twin-T Second Order Highpass non-inverting
• First Order Lowpass III inverting
• First Order Lowpass I non-inverting
• First Order Lowpass II non-inverting
• Akerberg-Mossberg (AM) Second Order Lowpass inverting
• KHN (Inverting Input) Second Order Lowpass inverting
• Multiple Feedback (MFB) Second Order Lowpass I inverting
• Multiple Feedback (MFB) Second Order Lowpass II inverting
• Bach Second Order Lowpass non-inverting
• Berka-Herpy (BH) Second Order Lowpass non-inverting
• Fliege Second Order Lowpass non-inverting
• KHN (Non-Inverting Input) Second Order Lowpass non-inverting
• Mikhael-Bhattacharyya (MB) Second Order Lowpass non-inverting
• Sallen-Key (SK) Second order Lowpass I non-inverting
• Tow-Thomas (TT) Second Order Lowpass non-inverting
• Twin-T Second Order Lowpass non-inverting

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AUDIO POWER AMPLIFIERS

• 100W Amplifier
• 18W Audio amplifier
• 25W MOSFET amplifier
• Headphone amplifier
• Portable headphone amplifier
• 2W amplifier
• 8 watt audio amp
• 20W Amplifier
• 50W Amplifier
• Two transistor audio amplifier
• Personal stereo audio amp
• Headphone amplifier
• 1.5W Audio amplifier
• Low-level audio amp
• 10W amplifier
• 80W amplifier
• LM383 12V Amplifier
• 100W Audio amplifier
• 100W RMS Amplifier
• 2-Channel Power Amplifier
• Push-Pull Class A Amp using type 5687 dual triodes
• Push-Pull Class A 2A3 Stereo Amp
• Single Ended Class A2 SV811-10 Stereo Amp
• Audio amplifier output relay delay
• HeadBanger Headphone Amp
• 2W Amplifier
• TDA2030 8 Watt amplifier
• 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

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AUDIO PREAMPLIFIERS

• Phono preamp
• Microphone amplifier
• RIAA phono amplifier
• Simple microphone preamplifier
• Phono Preamp
• Simple microphone preamplifier
• ECM Mic preamp
• Hi Fi preamp
• Electret mic amplifier
• Audio preamplifier
• Audio preamp
• Low impedance microphone amplifier

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AUTOMOTIVE MOTO

• Analog Tachometer for Gasoline Engines
• Headlight On reminder with Light
• Flashing High Intensity LED 3rd Brake Light
• Speed limit alert
• Portable CD Player Adapter For Car
• Car battery charger
• Wireless Auto Tachometer
• Electronic auto stethoscope
• Turn signal alarm
• Motorcycle turn-signal system
• Cigarette lighter 9V adaptor
• Headlight reminder
• Breath Alcohol Tester controlling a car ignition system
• Simple Car Preamplifier and Artificial Earth
• Interface between GM's 5 Volt 8192 baud ALDL data stream and a PC serial port
• 3rd brake light
• 12V to 9V car coverter
• Car Nicad charger
• Economy radar detector

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DATA AQUISITIONS

• TempSentry temperature sensor technical info and schematics
• Datalogger based on 68HC11
• Analog input section based on AD9220
• Digital remote thermometer
• Light direction sensor
• 12-Bit ADC interface
• Digital thermometer
• Compost temperature and moisture monitor
• Rain detector
• Air flow detector 1
• Air flow detector 2
• Strain gauge sensor
• Web-based thermometer project
• Honey Bee counter (PDF)
• Capacitance type liquid level measurement (PDF)
• Digital PC Oscilloscope
• Serial Port A/D-converter
• Centronics port D/A converters and low-pass filter
• Inclinometer using ADXL05
• Water-level sensor

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FOR GAMES

• Big Mouth
• GameBoy Camera Parallel Port Interface
• PSX controler to PC MIDI converter
• GameBoy Cart Programmer
• Pine Racecar Victory Judge
• Electronic coin tosser
• Electronic craps game
• First response monitor
• PowerGlove Interface
• 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
• DIT shutterglasses controller







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