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Do It Yourself Projects #4

Posted 25 May 2005
Updated 27 May 2005

Here are some of the "Best of the Best" Projects and "How-To" Pages I've wandered upon in my treks across the Net.


Audio Power 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 Amplifier
  • 18W Audio amplifier
  • 25W MOSFET amplifier
  • Headphone amplifier
  • Portable headphone amplifier
  • 2W amplifier
  • 4W amplifier
  • 8 watt audio amp
  • 20W Amplifier
  • 50W 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
  • Spatial Distortion Reduction Headphone Amp
  • HeadBanger Headphone Amp
  • 2W Amplifier
  • TDA2030 8 Watt amplifier
  • Headphone distribution amp
  • 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
  • Power amp schematic (PDF)
  • 20 Watt Class-A Power Amplifier
  • El-Cheapo - A Really Simple Power Amplifier
  • Single Chip 50 Watt / 8 Ohm Power Amplifier
  • Hi-Fi Headphone Amplifier
  • 100W Guitar Amplifier
  • Death of Zen (DoZ) - A New Class-A Power Amp
  • Soft-Start Circuit For Power Amps
  • Thermo-Fan To Keep Your Amp Cool
  • Audio Amp Output Power Limiter
  • 55W (Originally 75W) Power Amplifier
  • 300W Subwoofer Power Amplifier
  • 20 Watt / Channel Stereo Power Amplifier
  • Mini bench amplifier (LM386)
  • 12 Watt Valve Guitar Amp

  • Audio Preamp

  • Microphone amplifier
  • RIAA phono amplifier
  • Low impedance microphone amplifier
  • Dynamic microphone preamplifier
  • Phono preamp
  • Masthead preamp
  • Preamplifier for microphone or guitar use
  • Simple microphone preamplifier
  • Tube microphone preamp
  • Simple Stereo Electret Microphone Preamplifier
  • Simple Stereo Electret Microphone Preamplifier
  • Phono Preamp
  • Simple microphone preamplifier
  • ECM Mic preamp
  • Hi Fi preamp
  • Balanced microphone preamp
  • Audio preamp
  • Electret mic amplifier
  • Audio preamplifier
  • Vacuum Tube Microphone Preamp
  • FET Preamp Cable
  • Audio preamp

  • Miscellaneous Audio

  • 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
  • Audio level indicator
  • Room noise detector
  • Amplifier timer
  • Bell ring generator
  • Amplified ear
  • Precision audio millivoltmeter
  • Six-channel Mixer and Amplifier
  • Audio Signal Source
  • Analog VU meter
  • Voltage controlled amplifier
  • Audio graphic equaliser
  • Intercom preamp
  • FET audio mixer
  • Microphone mixer
  • Tone control
  • Digital volume control
  • Sound level meter
  • CMOS IC audio oscillator
  • Three band Active Tone Control
  • Automatic gain control (AGC) circuits
  • Audio frequency meter
  • Bull Horn
  • Sound Mixer/Amplifier
  • Very loud beeper (PDF)
  • Digital noise generator (PDF)
  • Tone display system
  • Tube amplifier
  • Condenser microphone hookup
  • Phase shifter
  • Paradoxical Sound Syntheizer
  • Various tube crossover circuits
  • Bias circuits
  • Audio line isolator
  • Dynamic microphone to electret microphone input
  • Line level signal to microphone input adapter
  • Simple two line output combiner
  • Electret microphone powering circuits
  • Use amplifier phono input as line level input
  • Speaker signals to line level inputs
  • Spring reverb unit
  • Sine wave generator
  • Simple amplifier
  • 3-Band equalizer
  • 6-Input mixer
  • Doorphone intercom
  • Stereo line driver
  • Audio notch filer
  • Peak reading audio level meter
  • Tone control
  • Speaker Microphone Circuit
  • Electronic canary
  • Electronic siren
  • Microphone phantom power supply
  • 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
  • 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
  • Surround Sound Decoder Mk2
  • Audio mixer



  • Filter

  • Galaxy Noise Filter
  • Low-pass active filter
  • Filter Circuit for the Earthworm Seismic Data Acquisition System
  • Active 2nd Order Filters
  • RC Notch Filter (Twin T)
  • Multiple Feedback Bandpass Filter
  • CW filters
  • Self-tune filter
  • SSB AF filter
  • Helical Resonator Notch Filter
  • 3KHz low-pass filter plus audio amp (PDF)
  • Active bandpass filters
  • Bandpass filters
  • Butterworth filters
  • Narrow band audio bandpass filter
  • Inversal notch and bandpass filter
  • DC Accurate, Active RC Lowpass 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
  • LC filter design

  • Games

  • 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
  • Mobile robot (PDF)
  • PSX controler to PC MIDI converter
  • Dreamcast PC serial adapter
  • GameBoy Cart Programmer
  • Memory game
  • 32 Kb x 8 emulator for the GameBoy
  • Project: NES to Atari 2600 controller interface
  • Battery Meter for Pinball Machines
  • SRX1 (Stephane's Robotic eXperiment 1)
  • Pine Racecar Victory Judge
  • Interfacing Sony control stick to Empeg
  • Electronic Nicad glow plug driver
  • April Fools LEDs
  • Pinewood Derby logic
  • Quiz Master
  • GameBoy Schematic
  • GameBoy LCD schematic
  • GameBoy Power & Cartridge schematic
  • GameBoy ROM+RAM+MBC1 Cart Schematic
  • GameBoy MBC1 circuit equivalent
  • Super GameBoy schematic
  • Quiz show indicator
  • Dreamcast interface
  • Bingo!!! (on your tv)
  • Slot car TV cronograph
  • Furby reverse-engineered circuit
  • Sanyo 20EZ monitor Arcade Game (300k ZIP)
  • Burger Time Arcade Game (500k ZIP)
  • Dig Dug Arcade Game (800k ZIP)
  • Frogger Arcade Game (500k ZIP)
  • Galaga Arcade Game (542k ZIP)
  • Gyrus Arcade Game (800k ZIP)
  • Junior Pacman Arcade Game (400k)
  • Ladybug Arcade Game (335k ZIP)
  • Mappy Arcade Game (470k ZIP)
  • Moon Cresta Arcade Game (300k ZIP)
  • Mr.Do Arcade Game (554k ZIP)
  • PacLand Arcade Game (316k ZIP)
  • Pengo Arcade Game (313k ZIP)
  • Q*Bert Arcade Game (600k ZIP)
  • Qix Arcade Game (476k ZIP)
  • Scramble Arcade Game (600k ZIP)
  • Time Pilot'84 Arcade Game (870k ZIP)
  • Xevious Arcade Game (450k ZIP)
  • Magic Wand Conjuring Trick
  • Quiz game circuit
  • E.S.P. Conjuring Trick
  • Video game system using PIC18F252 (direct video generation)
  • Video game system using SX28 (direct video generation)
  • DIT shutterglasses controller
  • Tic-tac-toe game using PIC16F628
  • Archery timer
  • PIC micro Tetris game
  • Magic lamp, IR remote control jammer and other fun circuits (PDF)
  • Lego Mindstorms Double Rotation Sensor

  • Medical and Health

  • Snore alarm electronic device
  • Heartbeat transducer
  • ECG Amplifier
  • EKG/EEG circuit
  • Radiation Dosage-Rate Meter
  • Heartbeat monitor
  • Cranial Electrotherapy Stimulator
  • Automated crib lights
  • Jogging timer
  • Tan timer
  • Muscular Bio-stimulator
  • Pedometer
  • Simple lie detector
  • EEG preamp, anti alias filter and isolation circuit
  • Self Contained Electromyograph (EMG)
  • Cardiac monitor
  • Galvanic Skin Response (GSR) Schematic
  • Brain-Wave Machine
  • Lie detector
  • Simple lie detector
  • ECG project page
  • The ESP SIM (Sound Impairment Monitor)
  • Respiration system

  • Models

  • Snake throat muscle controller
  • Handy cricket for robotic applications
  • Incline Railway Control Circuit
  • A Receive Signal Decoder
  • 27Mhz toy car receiver
  • 27Mhz toy car transmitter
  • One ounce rocket ejection timer
  • LED traffic lights
  • Two-tone siren
  • Proportional radio remote control
  • Alf: The Robotic Matchbox car
  • Seaplane schematic
  • Model Rocket with Video Camera
  • Signal breaking module
  • RF serial link for robot
  • PIC based rocket altimeter
  • Robot with PIC16F84 brain & InfraRed eyes
  • 0-10V control for RC servos
  • Robotic microcontroller board
  • Multi Rocket Launcher
  • Model rocket launch controller
  • Pad launch controller for model rockets
  • Simple flashing light circuit
  • Simple flashing light circuit
  • A dual alternating flashing light circuit
  • Simple flashing light circuit
  • A dual tandem flashing light circuit powered by a 9 volt battery
  • Simulate the Gyralite (dual flashing headlights).
  • Simple train detector using ambient light and a photocell
  • Simple charge rate monitor
  • Deluxe charge rate monitor
  • "CLONEPAC" memory module for Futaba 8UAF/8UAP
  • Battery pack discharger
  • Plane locator
  • Plane locator 2
  • Battery low voltage alarm
  • Battery low voltage alarm 2
  • Ultimate battery low voltage alarm
  • R/C digital camera controller
  • R/C helicopter camera
  • Building an RF Remote Control System
  • Motor walker circuit
  • 250-amp Speed Controller for RC cars
  • Spider robot electronic project page
  • Two tone train horn
  • R/C Emergency locator alarm
  • Remote switch for radio-control aircraft accessories
  • Radio Control Battery Backup
  • Glow Plug driver for model engines

  • Music

  • 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
  • Colour organ light
  • MP3 Player
  • Metronome and pitch generator
  • Mini metronome
  • Compact Flash / IDE MP3 Player MKI
  • Simple colour organ
  • Guitar fuzz effect
  • 8 note tune player
  • Colour (Sound) Organ
  • Transisor organ
  • BookPC Car MP3 Player
  • Yet Another Mobile MP3 Player
  • Wave Multiplier for music synthesizers
  • Vibrato Circuit for Guitar, Steel, Bass, Etc.
  • MIDI status indicator
  • 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
  • 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


  • Low in Fat • No Frames • No Cholesterol • No Sounds (well, one)
    High in Fiber • No Movies • No MSG • No Animation (well, very little)
    Kudzu Free (impossible) • Absolutely No Cookies
    and Now with a Drop of Retsin™.

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    MicroMax Systems Inc.