Pocket Synth

A portable CMOS synthesizer based on the CD40106.

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This is a very basic synthesizer based on the Schmitt trigger oscillators in the CD40106. Each of the three is playable with a CdS photocell on the top of the enclosure.

  • 1 × CD40106BE Logic ICs / Gates and Inverters
  • 3 × CdS photocells Light-dependent resistors
  • 3 × 100kΩ resistors These are for mixing the oscillator outputs together
  • 1 × .68μF capacitor .68uF, .1uF, 1uF
  • 1 × .1μF capacitor

View all 9 components

  • Ta-da!

    kristina panos03/05/2015 at 23:06 0 comments

    As you can see from the gallery and the YouTube video, this is finished and working. I edited the components list to show the capacitor values I decided on.

  • Spitballin'

    kristina panos02/28/2015 at 19:47 0 comments

    Design circuit with the enclosure in mind.

    • Inputs are LDRs, so they must be accessible to the user.
    • Enclosure is metal. Must not short things together.
    • Oh yeah, I have some tiny heart-shaped foam stickers. I'll poke the LDR legs through them and stick them to the top of the box.
    • I can use wire insulation as leg warmers on the LDRs, since I'm running out of really skinny heat-shrink tubing.
    • LDR legs must be lengthened so that the user can replace the battery without destroying the circuit.
    • Okay, cool. If I wire-wrap the legs once I stick them through the lid, they'll have nice, flexible extensions to the board. Plus, I get to wire-wrap.

    Find the most appealing capacitor values.

    Sure, this is an extremely lo-fi synth. But it might as well be as appealing to play as possible. I have three sizes of LDRs, so it's worth experimenting with capacitors to find pleasing frequency ranges.

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  • 1
    Step 1
  • 2
    Step 2

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davedarko wrote 03/01/2015 at 23:45 point

I've been searching a while for this link: - I wonder if it is possible to make a (polyphonic) melody combining this with your box.

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kristina panos wrote 03/02/2015 at 16:41 point

Oh, that is awesome. I have something else in mind for the immediate future, but maybe I'll give this a go after.

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