Complete List Of Electronics Projects

Alarm and Security

Drinking Water Alarm
Anti-Theft Security For Car Audios
Luggage Security System
Power Buzzer
Infrared Proximity Detector Alarm
General-Purpose Alarm
Simple Darkness Activated Alarm
Model Railway Short-Circuit Beeper
Gated Alarm
Laser Alarm
Low-Cost Low-Intensity Alarm
Speed Alarm For Cars
Remote Alarm For Smoke Detector
Simple 6-Input Alarm
Night Alert
Simple Knock Alarm With Piezo Sensor
Smoke Alarm Battery Life Extender
Mains Supply Failure Alarm
Bell Alarm
Water Alarm Circuit Diagram
Midnight Security Light
Low Cost Burglar Alarm For Boats
Water Level Alert
Two-Tone Siren Using One IC
Fridge Door Alarm
Broken Charger Connection Alarm
Fire Alarm Using Thermistor
Safety Guard
Powerful Security Siren
Mini Alarm

Amplifiers

Super Simple 3 Watt Audio Power Amplifier
Modular Headphone Amplifier
High Power Headphone Amplifier Using BD139-40
Dual Power Amplifier Using TDA7293 MOSFET IC
Low Cost 2x20 Watt Stereo Amplifier by TDA2005
AF Amplifier With Digital Volume Control Based On TDA8551
11W Stereo/22W Mono Power Amp Using TDA1519C
5.3W Amplifier With Surround System
Balanced Microphone Amplifier
Headphone Amplifier Using Discrete Components
22W Stereo Amplifier Using TDA1554
Compact DJ Station
10W Audio Amplifier With Bass-Boost
Guitar Amplifier
Mini Guitar/Bass Amplifier
Playback Amplifier For Cassette Deck
1W BTL Audio Amplifier
Very Simple Bench Amplifier
Boomer Audio Power Amplifier Using LM4906
Condenser Mic Audio Amplifier
60 Watt Guitar Amplifier
60 Watt Bass Amplifier
Mini Portable Guitar Amplifier
22 Watt Car Subwoofer Amplifier
Hybrid Headphone Amplifier
USB Powered Audio Power Amplifier
DC-Coupled Audio Amplifier
Simple Hybrid Audio Amplifier
Compact High-Performance 12V 20W Stereo Amplifier
36 Watt Audio Power Amplifier Using TDA1562Q
Studio Series Stereo Headphone Amplifier
45 Watt Class-B Audio Power Amplifier
60 Watt Audio Power Amplifier
18W + 18W Stereo Hi-Fi Audio Amplifier (TDA2030)
A Low Power Wireless Audio Power Amplifier
8 Watt Audio Power Amplifier
A High Quality Headphone Amplifier
30 Watt Audio Power Amplifier
Pure Class-A Headphone Amplifier
Stereo Headphone Amplifier
7 Watt Audio Power Amplifier
Portable Headphone Amplifier
25 Watt Audio Amplifier
5 Watt Class-A Audio Amplifier
18watt Audio Amplifier
Headphone Amplifier
2Watt Audio Amplifier
Portable 9v Headphone Amplifier
Speech Amplifier

Audio and Music

Optimized Semiconductor Noise Source
Symmetric Noise Source
US-Style Siren
Multi-Sound For Guitars
General Purpose Oscillator
Oscillation Monitor
Pan Pot
Mini Audio Signal Generator
Sounds From The Old West
Guitar Control
Cheapskate's Headset Adapter
Dual Input-Combining Stereo Line Amplifier
Steam Whistle
Audio Level Threshold Control
Multi-Melody Generator With Instrumental Effect
IR Music Transmitter and Receiver
Multi-tone Siren
Sound Source Locator Uses PreChamp
Audible Flasher Warning
Surf Simulator Circuit Diagram
When The Siren Sounds - A Useful Circuit
Simple White Noise Generator
Balanced-Unbalanced Converter For Audio Work
Automatic Loudness Control
Cuckoo Sound Generator
Cricket Chirping Generator
Bells Ring Generator
Melody Generator
4 Channel Portable Audio Mixer
Music Generator Schematic Using UM66
Laptop Audio-Out Splitter
Three Channel Audio Mixer
Digital Volume Control
Stereo to Mono Converter Based on FET
Three Channel Audio Splitter

Automotive

Brake Light Signal Module
Car Battery Saver
Car Boot Lamp Warning (ICM7556)
Lambda Probe Readout For Carburetor Tuning
Lights On!
Rear Light After Glow (For Bicycles)
Car Interior Lights Delay
Park-Aid Modification
Park-Aid
Push-Bike Light
Speed-Limit Alert
Headlight Reminder
Automatic Headlight Reminder
AFX Slot Car Lap Counter
Petrol Gas Switch For A Pajero
Car Reversing Horn With Flasher
Bicycle Speedometer With Hub Dynamo
Rear Fog Lamp For Vintage Cars
Central Locking Interface
Automatic Windshield Washer Control
Simple Headlight Reminders
LED Bike Light
Fog Lamp Switch
Fog Lamp Sensor
Flashing-LED Battery-Status Indicator
Motor Bike Headlight Controller
Car-Bulb Flasher

Battery and Chargers

Battery Juicer
Li-Ion Battery Charger
Lead Acid Battery Charger #1
Lead Acid Battery Charger #2
Deluxe Charge Rate Limiter for Small Capacity NiCad Batteries
Electric Window/Fence Charger
Versatile Micro-power Battery Protector
Battery Equality Monitor
12 Volt Battery Guardian
Battery Saver
PC-Powered Battery Charger
A 12V Car Charger For ASUS Eee Notebook
Simple Battery Discharger Using Discrete Components
Battery Charger Display Using LT1639
Battery Switch With Low-Dropout Regulator
Motorcycle Battery Monitor
NiCd Battery Charger
Float Charger For NiMH Cells
Simple Battery Isolator
Simple NiCd Battery Charger
NiMH Charger For Up To Six Cells
Nicad Charger Uses Voltage Cut-Out
Battery Desulphation Progress Monitor
Storage Battery Exerciser
Switch-less NiCd-NiMH Battery Charger
Solar-Powered High Efficiency Battery Charger
Low-Voltage Cutout For 12V SLA Batteries
Bike Battery Charger
Simple Battery Charger - Charges Upto 12 NiCD Cells
Solar Battery Protector Prevents excessive Discharge
Low Cost Battery Condition Indicator
12V Lead Acid Battery Desulphator
High-Current Battery Discharger
Solar Panel Based Charger And Small LED Lamp
Battery Charger Regulator
Low-Power Car/Bike USB Charger
Lithium-Polymer Peak Charger
In-Car Charger And Switcher For SLA Battery
Mobile Phone Travel Charger
NiCd Battery Charger With Reverse Polarity Protection
NiMh and NiCd Battery Charger
USB Powered Mobile Phone Battery Charger
12 Volt Car Battery Charger
A Friendly Charger for Mobile Phones
Low Cost Universal Battery Charger
Mobile Cell phone Battery Charger
Mobile Phone and iPod Battery Charger
Mobile Phone Battery Charger
Dry Cell Battery Charger Using LM741

Boosters

Step-Up Booster Powers Eight White LEDs
Input Impedance Booster II
Input Impedance Booster
10,000x With One Transistor
Low-Power Voltage Doubler (Booster)
Pump it up: Mp3 Booster
Ampere or Current Booster Circuit
Bass Booster Circuit
Audio Booster

Clock and Timers

Flip-Flop Timer Using 4017
Three Hour Timer
Isolated 1-Hz Clock
Egg Timer
Alarm Clock With Day Selector
Thrifty 2Hz Clock
Experimental Pendulum Clock
An Accurate Reaction Timer
Switch Timer For Bathroom Light
Up/Down Timer For A Power Antenna
Pendulum-Controlled Clock
Multipurpose Flip-Flop Timer
555 Timer With Variable On/Off Times
Building A Synchronous Clock
Long Delay Timer
Jogging Timer
Amplifier Timer
One second Audible Clock
Car Headlights Timer
A Tan Timer
A Very Useful Timed Beeper
A Bedside Lamp Timer

Computer Related

CD-Rom Drive as Digital-Audio CD Player
Serial To Parallel Converter
Automatic Mains Disconnect
Case Modding
Processor Fan Control
IrDA Interface
Home Network for ADSL
How To Connect Two Computers Using Modems
Monitor Life Extender
Digital Isolation up to 100Mbits
Speaker-Headphone Switch For Computers
Computer Off Switch
Hard Disk Switch
USB Fuse
USB Power Socket With Indicator
USB Switch For Printers
Laptop Protector
USB Operated Home Appliances
USB Printer Share Switch
USB Power Injector For External Hard Drives

Filters and Oscillators

Baud Rate Generator
Comparator Based Crystal Oscillator
HQ Notch Filter Without Close-Tolerance Components
Simple Function Generator
Very Low Power 32kHz Oscillator
Voice Bandwidth Filter

Health and Hobby

ECG Amplifier By TLC274
Railway Points Sequencer
Pulse Rate Monitor
Pills Reminder
Quick Counter For Young Children
LED Noughts And Crosses
LED Chaser Provides Three Game Functions
Low-Cost Dual Digital Dice
Soldering Iron Tip Preserver
Gym Agility: A Simple Strategy Game
Heart Rate Monitor
Call Acknowledged !
Model Railway Turnout Control
Transcutaneous Electrical Nerve Stimulator (TENS)
Tablet Reminder Uses Watch Module
123 Game - All MCU-free
Dicing With LED's
Cranial Electrotherapy Stimulator
Pulse Generator And Signal Tracer
Whistle Responder
Sleeping Aid
Digital Step-Km Counter

Home and Garden

Remote-Controlled Fan Regulator
Laser-Guided Door Opener
Automatic Room Power Control
Water Level Indicator Using 7-Segment Display
Rainwater Storage Gauge
Cat and Dog Repeller
Inexpensive Remote Watering System
You Have Mail!
Whistling Kettle
Doorbell Cascade
Gentle Breeze
Automatic Range Hood
12V Fan Directly on 220V AC
Environmentally-friendly Mosquito Repeller
Doorbell Memory
Fridge-Door Open Alarm
Automatic Water Tank Filler
Digital Remote Thermometer
Plant Watering Watcher
Salt Taster
Fridge Door Alarm Schematic 2nd Version
Room Noise Detector
Water Level Alert
Heating System Thermostat

Indicators

Fastest Finger First Indicator
Digital Main Voltage Indicator
Mains/Fuse Failure Indicator
Modem Off Indicator
LED Bar Off Indicator
Supply Voltage Indicator
Fuse Monitor
Audio Clipping Indicator
Battery-Charging Indicator For Mains Adaptor
Telephone In-Use Indicator
Battery Self Discharge Indicator
Two-LED Voltage Indicator
Blinker Indicator
Yes-No Indicator Has Zero Standby Current
Low Battery Indicator II
Low Battery Indicator I
Maximum Minimum Voltage Indicator
Clipping Indicator For Audio Amplifiers
Mains Indicator
Earth Fault Indicator
Blown Fuse Indicator
Battery Indicator For The Caravan
110 and 220V AC LED Voltage Indicator
Water Level Indicator
DC or AC Voltage Indicator
Battery Voltage Indicator
Peak Indicator
Audio Indicator Using LM741

IR (Infra-Red)

Simple Remote Control Tester
Simple Infrared Remote Control Extender
Infra-Red Sensor/Monitor
Infra-red Light Barrier Using 555
RC5 Repeater
Light Gate With Counter Using 555 And 4033
IR–S/PDIF Transmitter
IR–S/PDIF Receiver
IR Remote Control Receiver
Infra-red Receiver
Simple Infrared Control Extender
Direction Sensitive Light Barrier
Infrared Remote Receiver Has Four Outputs
RC (Remote Control) Switch
Infrared Remote Extender
Infrared Fire-Cracker Igniter
Long-Range IR Transmitter
On-off Infrared Remote Control
TV Muter
IR (Infrared) Detector
Beam-break Detector For Camera Shutter or Flash Control
Remote Operated Home Appliances
Wireless On-Off Switch
Active High Pass Filter Using LM741

Inverters and Converters

500W Low Cost 12V to 220V Inverter
UPS For Cordless Telephones
Discrete Voltage Inverter
Voltage Inverter Using Switch-Mode Regulator
4-Bit Analogue to Digital Converter
12V Fluorescent Lamp Inverter
Cheap 12V to 220V Inverter
Inverter For Soldering Iron
100W Inverter

Lights and LEDs

White LED Lamp
12 Volt DC Fluorescent Lamp Driver
Fine Control Super Bright LED Pulser
Bar-Mode Lights Sequencer
LED–LDR Blinker
Magic Lights
Picnic Lamp
High-Intensity, Energy-Efficient LED Light
Soft Start For Torch - Increases The Life Of Torch Bulbs
Two-Position Dimmer
220V AC Powered Blinking LED
EL Lamp Driver Using HV832MG
Vehicle Interior Lighting With Switch-Off Delay
LED Flasher
Reflector For Pedestrians
Mains Powered White LED Lamp
Luxury Car Interior Light
Multi-Color LED
Automatic Light Dimmer
6-Channel Running Light
LED Lighting For Consumer Unit Cupboard
Light From Flat Batteries
Flickering Light II
30mA LED Dimmer
Backup Lamp
Dimmer With A MOS-FET
1W LED Driver
UV Torch Light
LED Light Pen
Irregular Flasher
Bluish Flasher
Novel White LED Torch
12V Halogen Dimmer
Automotive LED Timing Light
Economical Desk Lamp For Camping
El-Cheapo Fluoro Ballast
Exit Sign With Battery Protection
Stroboscope Uses White LEDs
Courtesy Light Extender
Model Theatre Lighting Dimmer
Using AC for LED Christmas Lights
LED Lighting For Dual-Filament Lamps
Constant Current LED Drive
Automatic White-LED Garden Light
Interactive Toy Traffic Lights
Traffic Lights For Model Cars Or Model Railways
Neon Flasher Runs From 3V Supply
LED Torch Uses Blocking Oscillator
Grand Prix Starting Lights
Halogen Lamp Dimmer With Soft Start
Thrifty LED Protector
Driver For 20 LEDs
Multicolor HD LED
Automatic Light Controller Using 7806
LED Phototherapy Unit
Using LED As A Light Sensor
Slave Flash Trigger
Ultra Bright LED Lamp
Portable Lamp Flasher
One Of Nine Sequencer
12V Dimmer
Fully Automatic Emergency Light
Solar Lamp Using PR4403
Slave Flash Trigger
Put That Light Out
High-intensity LED Warning Flasher
Smooth Flasher
The Itsy-Bitsy USB Lamp
Midnight Security Light Circuit Schematic
IC Controlled Emergency Light With Charger
Electronic Candle Blow Out
Flashing-LED Battery-Status Indicator
Fading LEDs
Dancing LEDs
Bicycle Back Safety Light
Automatic Low-Power Emergency Light
Two Flashing LEDs
Mains Operated LED
AC 220 Volts Flashing Lamps
Brightness Controller For Small Lamps and LEDs
LED or Lamp Pulsar Circuit
LED or Lamp Flasher
Emergency Light and Alarm
Two-LED Pilot Light
Flashing Eyes
Dark Activated LED or Lamp Flasher
Battery Powered Night Lamp
Courtesy Light
Dark Activated Terrace Lamp

MCU - Microcontroller

PIC Controlled Relay Driver
LCD Module in 4-bit Mode
AVR Dongle
USB-Powered PIC Programmer
Programming The Propeller IC
Contrast Control for LCDs
Simple Universal PIC Programmer
Intelligent Presence Simulator
The Gentle Touch
Multitasking Pins
DCF77 Preamplifier

Microphone

Electronic Ear for Lego RCX Module
Low-Noise Microphone Amplifier (OP270E)
Compressor For Electret Microphone
Speech Eroder
Room Recorder
Spy Ear
Clap Sensitive On-Off Relay
Hearing Aid
A Low Cost Hearing Aid
Amplified Ear

Motor Control

Electronic Motor Starter
PWM Dimmer/Motor Speed Controller
Stepper Motor Generator
Bipolar Stepper Motor Control
Rolling Shutter Motor Control
Fan Controller Using Just Two Components
Reservoir Pump Controller
Solar Hot Water Panel Differential Pump Controller
Stepper Motor Generator
Luminescent Generator
Motor Turn Stall Detector
Two Basic Motor Speed Controllers
Cheap Pump Controller
Efficient Fan Speed Controller
Light-Controlled Pond Pump
Junk-box Fan Speed Controller
Pump Controller For Solar Hot Water System
Stepper Motor Controller
DC Motor Speed Controller
Discrete PWM Generator
12V Speed Controller/Dimmer

Power (Mains)

Non-Contact Power Monitor
Contact-less AC Mains Voltage Detector
Supply Voltage Monitor
Electrical Isolation For I2C Bus
Simple Electrification Unit
Mains Pulser
Power Flip-Flop Using A Triac
Mains Voltage Monitor
Mains Manager
Mains Slave Switcher II
Mains Slave Switcher
Mains Frequency Monitor
Smart Trailing Socket
Fuse Saver
Mini High-Voltage Generator

Power Supply

Dual Polarity Unregulated PSU For High-End Audio Amps
High Voltage Converter: 90V From 1.5V
Very Low Dropout Adjustable Breadboard Power Supply
3V Supply Splitter
Transformer-less Power Supply
Discrete Voltage Regulator
Simple Pre-Regulator
Dual Power Supply For Amplifiers
Switching Voltage Regulator
Low Power 12V Transformer-less Power Supply
High Input Voltage Linear Regulator
ATX Power Switch Substitute
Compact Switching Step-Down Converter By MAX639
DC/DC Converter From +1.5V To +34V
Dual Polarity 5 Volt Converter Using LM2685
9V DC Adapter With Battery Backup
3 Volts Car Adapter Using LT1074CT
Adjustable 3 Ampere Regulator
78xx Voltage Regulators
12V Glow Plug Converter
DC Control for Triacs
DMM Fuse Protector
Over-voltage Protection
Floating 9V Supply For DVM Modules
RS232 Voltage Regulator
555 DC/DC Converter
Low-Power Voltage Reference
Switch-Mode Power Supply
Low-Drop 5V Regulator
Thrifty Voltage Regulator
Ultra Low-Power 5V Regulator
Soft Start For Switching Power Supply
Alarm Power Supply
Fast Electronic Fuse
Logic PSU With Over-Voltage Protection
Polarity Reverser
Lead-Acid-Battery Regulator For Solar Panel Systems
Fast Voltage-Driven Current Source
Variable PSU
Reset from Multiple Power Supplies
Voltage Regulator Calculation
Reverse Polarity Protector
7.2V Battery Replacement Power Supply For Camcorders
Power Supply For USB Devices
5V Power Supply For On-Train Radio Camera
Negative Auxiliary Voltage
Stable Filament Supply
Voltage Levels Control Relays
Triple Power Supply
SMPSU With A Relay
Inductor-less 3-5 Volts Converter
Buck-Boost Voltage Converter
Adjustable Zener Diode
3.3 V or 5 V Direct from the Mains
100V Regulators
Fully Adjustable Power Supply
Battery Replacement Power Supply
Switch-mode Constant Current Source
Ultra Low Drop Linear Voltage Regulator
Short Circuit Protection For Balanced Supply Rails
Low-Cost Dual Power Supply
High Current Low-Dropout Voltage Regulator
Cheap Switch-Mode DC-DC Converter
8V DC Power Supply With Over-Voltage Protection
Low-Loss Step Down Converter
High-Voltage Regulator With Short Circuit Protection
Alternative Halogen Power Supply
Quad Power Supply For Hybrid Amplifier
Power MOS-FET Bridge Rectifier
Transformer-less 5 Volt Power Supply
Adjustable Current Limit For Dual Power Supply
Step-Down Converter Controlle
Stabilized Power Supply With Short-Circuit Indication
Protection For Voltage Regulators
Solar Cell Voltage Regulator
Low Voltage Step-Down Converter
48V Phantom (Microphone) Power Supply
12V Regulated Inverter Supply
9 Volt 2 Ampere DC Power Supply
3-30V 3A Adjustable Regulated DC Power Supply
Adjustable 1.3-22V Regulated Power Supply
5V Regulated Power Supply
1.5 - 35 Volt DC Regulated Power Supply
Ampere or Current Booster
Discrete Virtual Ground
Stabilized Regulated Power Suppl
Dual-rail Variable DC Power Supply
Dual Opamp Buffered Power Supply
Variable Dc Power Supply

Pulse and Frequency

Pulse Generator
1kH Synthetic Inductor
Frequency Doubler
1.2GHz VCO With Linear Modulation
Pulse Frequency Modulator
CMOS Crystal Frequency Multiplier
Optical Pulse Generator
Long-Interval Pulse Generator

RF (Radio)

Wire Tracer (Transmitter)
Wire Tracer (Receiver)
Low Power FM Transmitter
Simple RF Detector For 2M
One Transistor Radio
10 to 1000 MHz Oscillator
0-44dB RF Attenuator
Diode Radio For Low Impedance Headphones
Longwire Match For SW Receivers
FM Wireless Microphone
Active Short-Wave Antenna
Antenna Tuning Unit (ATU) For 27-MHz CB Radios
Sine Wave To TTL Converter
DRM Down-Converter For 455kHz IF Receivers
Tuned Radio Frequency (TRF) Receiver
SSB Add-On For AM Receivers
Single-Chip VHF RF Preamp
Shortwave Monitor
Antenna Input & Audio Lineout Adaptor For Portable Radios
Radio Controlled Electronic Flash
Simple AM Radio Receiver
Active Antenna
Opamp VHF FM Transmitter
Simple AM Transmitter
Simple Short-Wave Transmitter
Medium-Power FM Transmitter
Thunderstorm Predictor
Quality Stereo Wireless Microphone or Audio Link

Relay

Solar Relay
Reducing Relay Power Consumption
Audio Amplifier Output Relay Delay
Pushbutton Relay Selector
Relay Coil Energy Saver
Handy Time Delay With Relay Output
Momentary Switch Teamed With Latching Relay
Water Pump Relay Controller

Sensors and Detectors

Automatic Heat Detector
Tiny Dew Sensor
Two-Wire Temperature Sensor Using LM35
Sensitive Overload Sensor
Isolated Fuse Fail Indicator
Spike Detector For Oscilloscopes
Automatic Air Humidifier
Celsius Thermometer
Two-Wire Temperature Sensor
Infra-Red Proximity Detector
Infra-Red Level Detector
Simple Moisture Detector
Temporarily Silencing A Smoke Detector
Simple Audio Peak Detector
Pseudo Track Occupancy Detector
Acoustic Sensor
Car Battery Failure Detector
Super Light Sensor
Simple BFO Metal Locator
Body Charge Detector
Mobile Bug Detector
Temperature-Controlled Soldering Iron
Invisible Broken Wire Detector
Low Supply Rail Detection
Simple Short-Circuit Detection
Simple One-Wire Touch Detector
Simple Capacitive Touch Sensor
Temperature-Controlled Switch
Capacitive Sensor
Energy Leak Detector
Live Line Detector-Indicator

Speakers and Subwoofers

Crowbar Speaker Protection
Crossover For Subwoofer
Loudspeaker Protector Monitors Current

Switches

IR On/Off Switch Using Microcontroller
Smart Foot Switch
Time Switch

Heat Sensitive Switch
Clap Switch
Automatic Switch For Voltage Converters
Auto Power Off
On And Off Button
Clap-Controlled Switch
Push Off Push On
Master/Slave Switch
Low-Voltage Remote Mains Switch
Speaker-Headphone Switch For Computers
Petrol Gas Switch For A Pajero
RC (Remote Control) Switch
Mains Slave Switcher II
Computer Off Switch
Mains Slave Switcher I
Electronic Touch Switch
Hard Disk Switch
Temperature Sensitive Switch For Solar Collector
Remote Control Mains Switch
On Off Touch Switch
220V AC Lamp Toggle Switch

Telephone and Intercom

Low-Cost Transistorized Intercom
DTMF Receiver IC MT8870 Tester
Cordless Phone Backup
2-Line Intercom-Cum-Telephone Line Changeover
Watch-Dog For Telephones
Telephone Ringer Using Timer ICs
Telephone Call Voice Changer
Telephone Line Indicator
Telephone Free Indicator
Electronic Telephone Ringer
Aviation Intercom
Full-duplex Intercom
Telephone Ringer
Protection For Telephone Line

Test and Measurement

Transistor Tester
Measuring Inductors
High Side Current Measurements
Cheap And Cheerful Transistor Tester
Cable Analyzer
Thyristor Tester
Liquid-Crystal Display (LCD) Tester
Infra-red Remote Control Tester I
Three-State Continuity Tester
Infra-red Remote Control Tester II
Connection Tester
12/24/48 V D.C. Tester
Improved Vibrating Battery Tester
4-20mA Current Loop Tester
Servo Tester Using A 4538
Meter Adaptor With Symmetrical Input
El Cheapo Cable Tester
Four-Channel Oscilloscope Adaptor
Pipe Descaler
Curve Tracer Adaptor
Cable Tester Uses Quad Latch
Frequency Multiplier For LF Measurements
Capacitor Leakage Adaptor For DMM
Internal Resistance Tester For Batteries
Safe Oscillator For Watch Crystals
Simple Cat.5 Network Tester
Cheap AC Current Measurement
Computer Data Cable Tester
Battery Tester For Deaf and Blind Persons
Hyper-Simple Battery Capacity Tester
Harmonic Generator With Single Opamp
IR Remote Control Tester
Low Ohms Adaptor For DMM Based On An LM317 Regulator
Switchable Output Crystal Oscillator
Simple Logic Probe
Minimalist Oscilloscope
A Very Simple LED Tester
Car and Motorcycle Battery
Continuity Tester
LED Tester
Battery Tester
Quick On-Board Junction Tester
Components Voltage Tester
Self-Powered Fast Battery Tester
Circuit Board Checker
220vAC Operated Remote Tester
Infrared Remote Tester III

Tone Control and Preamplifier

Electric Guitar Preamplifier
Ultra-Simple Microphone Preamplifier
Modular Phono Preamplifier
Simple MD Cartridge Preamplifier
RIAA Phono Preamplifie
Balanced Microphone Preamplifier
Preamplifier For Soundcard
Ten-Band Equalizer
Treble Tone Control
Accurate Bass Tone Control
Passive RIAA Preamplifier
Multimedia RIAA Preamplifier
Paraphase Tone Controller
Preamp Stage For Ceramic Phono Cartridge Or Violin Pickups
A Balanced Output Board For The Stereo DAC
Modular Preamplifier Switching Center
Modular Preamplifier
Portable Microphone Preamplifier
Phono Preamplifier
Stereo Preamplifier With Bass Boost

Video

VGA to BNC Adapter (Converter)
Video-Out Coupling
RGB To Color Difference Converter
3-Input Video MUX Cable Driver Using LT1399
Video Amplifier
Video Tracer For Trouble-Shooting
NTSC-PAL TV Signal Identifier
Video Isolator

VU Meters

Simple Voltmeter
LED Volt Meter
Linear RF Power Meter
ESR & Low Resistance Test Meter
TV Relative Signal Strength Meter
Electronic Torricelli Barometer
Audio Power Meter
Save Your Ears - A Noise Meter

Miscellaneous

Dimmer Control Voltage Polarity Changer
RMS to DC Converter
Flip-Flop Using CMOS NAND Gates
Electronic Die
Opamp With Hysteresis
PWM Modulator
Cat And Dog Repellent
Reset Sequencer
Discrete Robot
Zero Gain Mod For Non-Inverting Opamp
Simple Under-Voltage Cut-Out
Simple Combination Lock
Logic Probe With Sound
Relative Field Strength Meter For A DMM
Simple 9-Way Cable Identifier
Dual Relay Driver Board