* Audio / music *

100W RMS amplifier

3-way 4th Order Active Crossovers for Car Audio

100W RMS amplifier

3-way 4th Order Active Crossovers for Car Audio

4W audio amplifier

8W audio amplifier

http://www.phy.ohiou.edu/~cigna/amps/

22W audio amplifier

50W audio amplifier

Audio line isolator

Audio preamplifiers

Colour (sound) organ

Digital sample rate converter

FET Audio mixer

Graphic equaliser

Guitar fuzz boxes

Guitar phaser

Headphone amplifier

IC audio preamp

LED VU meter

Low distortion audio amplifier

Microphone preamp

MIDI passthrough circuit

Multi-Mix Headphone Distribution Amp

Offset gain module

Paradoxical sound synthesiser

Phono preamp (valve)

Push-pull class A 2A3 stereo amp (valve)

Push-pull class A amp using type 5687 dual triodes

Ring modulator

SCMS killer for DAT recorders

Signal generator

Simple colour organ

Single Ended Class A2 SV811-10 Stereo Amp

Spring reverb unit

Transistor audio preamp

Transistor organ

Voltage controlled amplifier

Voltage controlled panner

* Automotive *

Breath Alcohol Tester controlling a car ignition system

Car battery charger

Wireless Auto Tachometer

* Computer related (non PC specific) *

Centronics port D/A converter

Joystick related projects

Getting power from serial port

HDLC adaptor for Atari ST

Null printer adaptor

RS-232 port monitor

Serial port A/D converter

Serial port relay control

* Consumer electronics *

Add 200 channels to PRO-43 scanner

Casio organiser interface

Home automation project

IR remote control repeater

Sharp organiser/pocket computer to RS-232 interface

The Propeller, a mechanically scanned LED clock

* Games and entertainment *

Powerglove to serial adaptor

* Microcontroller related *

68HC11 based data-logger

Basic stamp digital thermometer

Basic stamp light direction sensing

Closed caption decoder

F1 MC68HC11F1 based microcontroller - full circuit and PCB layout

iRX 2.0 PIC based microcontroller

Serial comms to LED driver

Serial port break reset circuit

Serial to parallel converter using the AT89C2051

Weighscale

* Models and model remote control *

Auto Reversing Circuit for Model Trains

Constant directional lighting #1

Constant directional lighting #2

Constant directional lighting #3

Constant directional lighting #4

Dual alternating flashing light

Dual tandem flashing light

Flashing light circuit #1

Flashing light circuit #2

Flashing light circuit #3

Infrared train detector

Intelligent glowplug driver

Simple train detector

Simulate gyrating headlight

* Motor, light and power control *

Battery discharger and status check

Current sensing relay driver

Diode constant lighting

Domestic heating boiler control

Fluorescent Lamps, Ballasts, and Fixtures

Light/dark activated relay

Power-line appliance controller

PWM light bulb regulator

PWM motor speed control

Servo motor info and schematics

More servo motor info and schematics

Stepper motor control circuit

Strobe light

Tacho generator motor speed feedback

Temperature controlled nicad charger

Temperature regulator

TRIAC light dimmer

Using a solenoid activated start gate

Xenon flash and strobe page

* Oscillators and timers *

Basic RF oscillator

Clock divider

Clock doubler for CMOS logic

CW beacon keyer

IC monostable multivibrator (555)

LM3909 LED flasher

Ramp generator, VCO, tri-stable oscillator

Squarewave to sine converter

Timers: delay on energise, delay on de-energise, latch

* PC related *

Barcode scanner

CCD video capture camera - circuit on request

Collection of ASCII PC related schematics

Computer controlled IR device

Connecting an AOR AR8000 or AR2700 to an IBM PC

Connecting Sega 3D glasses to a PC serial port

Data bus monitor

Interfacing the XC6200 Series

IR receiver for serial interface

Serial port A/D converter

Several PC related circuit and information files for FTP

Simple parallel port interface

TI-Calc to PC cable

* Power supplies *

12VDC To 120VAC Inverter

12 Volt low drop-out voltage regulated power supply

Adjustable power supply

Constructing low-voltage power supplies

Dual polarity power supply

High current power supply

Low-drop regulator (postscript file)

Simple regulated supply with overcurrent trip

* RF circuits *

1.5V tracking transmitter

50MHz Assistant (Preamp & Power Amp)

Active antenna

AM radio

Broadcast- quality FM transmitter

FET dip-meter

FM transmitter

Light sensing RF transmitter

Miniature FM transmitter #1

Miniature FM transmitter #2

Miniature FM transmitter #4

Op-amp radio

RF power meter

RF sniffer

Small FM transmitter

Several receiver circuits

Simplest RF transmitter

The smallest QRP transceiver for 80 meters

Transistor tracking transmitter

Various CW and AM transmitters

* Robotics (also see Motor, light and power control) *

Mobile robot

Robot limb control system

* Security and other sensors and detectors *

Collection of ASCII infrared related circuits

Garage door hacker

Infrared active motion detector

Infrared detector

Infrared to light converter

Rain detector

Security alarm

Smart card data monitor

Smart card to PC interface

Stepper motor as an encoder

Touch switches

More touch switches

Ultrasonic movement detector

Voice controlled switch

* Science related/novelty *

An inexpensive x- ray machine

Atom expander (LED light show)

Black light (battery powered invertor)

Building a Jacob's Ladder

Circuit to show chaotic dynamics

Ion detector

Laser power supply (reported as suspect design)

HeNe and solid state laser power supplies and notes (ASCII)

HeNe and solid state laser power supplies and notes (similar to above)

Lie detector

Metal detector

Rich detector

Several nuclear physics related circuits

Solid State Tesla Coil/High Voltage Generator

* Telephone related *

Caller ID

Circuit for phreaker's 'blue box'

Circuit for phreaker's 'pearl box'

Circuit for phreaker's 'red box'

Collection of ASCII phone related circuits

Cut phone line detector

FM bug

FM telephone transmitter

Noise reduction (filter) circuit

Phone busy indicator

Phone in use circuit

Telephone hold button

Telephone recorder

Telephone recording beeper

Telephone remote ringer

Universal telephone hold circuit

* Test and measurement *

20Msps Digital storage oscilliscope

Digital tester

Digital PC Oscilloscope

Resister substitution box

TempSentry temperature sensor technical info and schematics

* Files containing many circuits *

Sci.electronics FAQ: Assorted ASCII Schematics

--- Headlight Reminder Circuit
--- Parallel Port DAC
--- Quiz-Show Indicator
--- Frequency and Capacitance meter
--- CMOS Oscillator
--- Adjustable flashing LED
--- LED Display controller
--- Info on CO2 lasers wanted (ho hum)
--- Crystal 32.768KHz CMOS Oscillator
--- Crystal Oscillator
--- FM Oscillator
--- Video amplifier
--- 'Nixie' display tubes
--- Condenser microphone hookup
--- Bringing NiCd's from the dead
--- Phase shifter circuit
--- Ultrasonic transducer oscillator circuit
--- RR LED flasher (alternating)
--- HV supply: 12VDC in, 12KV out
--- Generating -5VDC from +5VDC
--- Ground loops
--- Peltier coolers/heaters

Sci.Electronics FAQ: Repair: Misc Related Schematics (ASCII)

--- Simple High Voltage Generator
--- Adjustable high voltage power supply
--- Panasonic VCR switching power supply (PV48XX and clones)
--- Variable intensity variable frequency stroboscope
--- Jacobs Ladders
--- Introduction to Curve Tracers
--- Curve tracer design
--- Quick and dirty curve tracer
--- In-circuit tester
--- Kevin's strobe schematics
--- Inverter and trigger circuits
--- Tiny tiny invertor design