ScratchBoard Emulator using Arduino Uno

Here is a circuit and arduino code to approximately emulate a ScratchBoard; there is sound, light, a button and four sliders but it isn’t a drop-in replacement.

Zip file download (55kB) contains a schematic (as a PNG graphic and as a TinyCAD file) and an Arduino sketch.

ScratchBoard Emulator Schematic (click image for full-size)

Various notes:

  • The electret mic used was an off-the-shelf component from Maplin Electronics.
  • the sound circuit is essentially “pinched” from the ScratchBoard (NB the circuit is intended to capture amplitude and not the actual audio waveform)
  • the 250k variable resistor provides some gain (amplification) control
  • there are some configurable parameters for the sound sensor in the sketch
  • remember to change the COM ports in the Arduino IDE and in Scratch so that they are not competing (if the Arduino is on COM3 then only one of the IDE or Scratch can use COM3 at a given time)
  • the arduino pinĀ  numbers in the schematic and in the sketch are matched so it should “just work” (build circuit, upload sketch, run Scratch)
  • configuring things in Scratch is a bit cryptic: you need to right-click on the “sensor value” block to show the “watcher” then right-click on that to set the COM port.
  • feel free to adapt and share… all is under open licence.


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