Some PDF's have PCB's generated for the circuit ready for construction.
Do check the scale of the drawing after you have printed it out.

Designs are available as GIFs and PDF's.
To open the simulations you will need Crocodile Clips v3 or 4 or LiveWire.

This page is currently being updated. Bold links in capitals lead to new pages for faster viewing of circuits. All circuits will be completed as time allows.

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FORMATS:
= CrocClips,
= GIF
= MGX Draw file.
= PDF
= Livewire
= PCB Wizard

Modified:
19:12, 25 August 2008

• AUDIO AMPLIFIER: PRE-AMP
  A low signal pre-amp using an op-amp from a single battery supply - -
• AUDIO AMPLIFIER: BRIDGED 20W 12v
  A common amplifier based around the TDA2005 IC.
• AUDIO AMPLIFIER: 7W
  A simple circuit based around LM383 - NOT TESTED
• AUDIO AMPLIFIER: 14W - NEW
  Single supply and split supply versions of the popular TDA2030 amplifier
• AUDIO AMPLIFIER: 32W - NEW
  Single supply and split supply versions of the popular TDA2050 amplifier
• AUDIO AMPLIFIER: GUITAR FUZZ
  A classic design based around an op-amp - NOT TESTED
• BASS/TREBLE TONE CONTROL
  A neat little circuit providing +/- 10dB bass and treble boost
• FILTER - ACTIVE LOW PASS - NEW
  Active filter based on Sallen Key design. Ideal for tone controls, subwoofer drivers and demodulating
• FILTER - ACTIVE HIGH PASS - NEW
  Active filter Sallen Key design. Ideal for tone controls, tweeter/midrange drivers and demodulating
• INTERCOM
  A neat little intercom with call facility using speakers as microphones.
• PARAMETRIC EQUALISER - NEW
  Tailor your audio with this variable frequency cut/boost filter
• RING MODULATOR - NEW
  Useful for sound effects - simple in design, based on just 2 transformers and 4 diodes - NOT TESTED
• SOUND ACTIVATED SWITCH
  This was connected to a battery powered mobile which activated when a baby cried
• TRIANGLE WAVE AUDIO ASTABLE - NEW
  A useful replacement for a sine wave generator, has AC/DC output and square and triangle outputs
• VCA - VOLTAGE CONTROLLED AMPLIFIER- NEW
  Fantastic little circuit that can be configured as a VCA, modulator and multiplier.

• LOTTERY NUMBER GENERATOR - UPDATED
  Good for generating those lottery numbers!
• 36 LED Chaser
  Example of multiplexed display to produce a chaser - LED's were mounted in a circle - - -
• 4 Way Spinner
  A 4 light bulb spinner that slows and stops on a random bulb. PCB included in pdf - - - -
• DIGITAL DICE AND DOUBLE DIGITAL DICE - UPDATED
  A electronic dice with LED display that powers down after 30 seconds
• Heads or Tails Coin Toss
  A simple way to generate an even mark/space ratio - -
• Roulette wheel v2
  A light sequencer with a few extra features. - - -
• Roulette Wheel
  A modification on the 36 channel chaser to get 37 LED's, enough for a roulette wheel - -
• Steady Hand Game
  A controller to use with a steady hand game - gives you up to 10 chances - -
• Survival Game
  Jump up the ladder withiout falling off, a game of skill - used in GCSE project - -

• BATTERY CHARGER - Constant Current
  A constant current fast charger for high current applications, RC etc. - -
• Bite Alarm - Pulsed Tone Generator
  Produces a pulsed tone with adjustable speed, duration, pitch and volume. - - -
• TIMED ENTRY/EXIT BURGLAR ALARM - UPDATED
  An alarm with a timed exit, entry and duration facility based around 2 x 555 timers
• DRILL SPEED CONTROLLER V2 - UPDATED
  PWM controller derived from a ramp generator and comparator - also drives lamps and other devices
• Fridge Alarm - version 1
  Activated by the light in a fridge or freezer. Sounds an alarm if the door is left open too long - -
• Fridge Alarm - version 2
  Same as before but produces a pulsed alarm tone - -
• Full Bridge Transistor Motor Driver
  An ingenious design that prevents shoot through, ideal for PWM/Robotics / Radio Control - -
• Intelligent Lithium/NiMH battery charger
  A nifty little circuit that monitors the battery voltage as it gets charged - -
• Race Starter Controller
  Ideal to enhance any Scalectrix race track. - - -
• Tank Heater
  A PWM power controller used to control the temperature in a tank for a tarantula - - -

• 1-90 Counter
  A neat little counter counting from 1 to 90 (not zero) with the aid of a few gates - -
• 24 Hour Clock
  A good example of using gates to "trap" binary count values - -
• Digital Stopwatch
  Times up to an hour in tenths of a second - -
• Door Monitor
  Counts the number of times a door is opened. Counts up to 9 but can be easily expanded - -
• Egg Timer
  A very simple 555 timer, activates a sounder at the end of the time period - -
• Large 7-segment Display board
  A resizeable display from 40mm to 150mm! - -
• Room Sentry
  Counts the number of people entering a room, for use with a PIR module - -
• Scalectrix Lap Timer
  Works by using an LDR under the track, times alternate laps in 10ths of a second - -
• Single Digit Scoreboard
  A compact general purpose display. - -

• 1.5v Battery meter
  Simple but effective way of testing 1.5 volt cells - -
• 12 Volt Car Battery Meter
  A 10 LED calibrated voltmeter from 11-15 volts, needs no extra battery - -
• Audio VU Meter
  A VU meter with 20 LED's. The input source can be a line input or a microphone - -
• FREQUENCY TO VOLTAGE CONVERSION
  Using the LM2917 for a few useful applications -
• LED Battery Meter
  Will measure any low voltage battery on a 10 LED scale! - -
• LED Strobe
  With high power LED's available, their replacement for a Xenon tube is viable! - -
• REV COUNTER
  A 10-LED Rev Counter/Tachometer using the LM2917. Also a general purpose frequency-voltage circuit
• TRIANGLE WAVE AUDIO ASTABLE - NEW
  A useful replacement for a sine wave generator, has AC/DC output and square and triangle outputs

• 12v Light Dimmer
  A basic light dimmer for lamps up to 24W - -
• Dog Warden
  A simple radio transmitter and reciever to signal when a dog has strayed too far - -
• INVERTER - NEW
  Generates a negative supply in a battery circuit for split power supply circuits.
• Knight Rider
  An adaption of the Light Bouncer makes a classic light chaser - -
• Light Bouncer
  A a simple chaser from a decade counter - bounces a light back and forth on 6 LED's - -
• Remote Control Beeper
  Uses RF Tx/Rx modules with a range of about 30m. - -