Monday 12 June 2017

Mictester - Silicon Tonebender

Found this while searching for some schematics for Silicon Tonebenders I came across it on revolutiondeux. Miro posted a layout awhile ago for the Hot Silicon, which is pretty much the same, the difference being the trimmer off the gain control (abuse) which lets you set the gain rather then having a set resistor. Since my layout different then his, and the added trimmer I figured it was worth adding.

Here's mictester's advice on tweaking:

"Adjustment: set the 1k "Abuse" pot halfway. Play though it, and adjust 5k preset until "gating" just stops. That's it!

You'll find that it has plenty of output, that the "Abuse" control gives a good range of colour, the "Sparkle" control has a very wide range and the sound is remarkably reminiscent of early Jeff Beck (certainly not a bad thing!).

Possible mods:

Put small value capacitors from base to collector of the middle two transistors - start with 47pF. This "smooths out" the sound a lot, but reduces the treble available.

If you have radio interference, put 100pF from base of the first transistor to ground.

Experiment with the capacitor values in the tone control - the 8n2 could go as low as 3n3, which would give a ridiculous range of treble control!

Increase the value of the 47k feedback / bias resistor - try as high as 470k. The gain will rise, the touch sensitivity will disappear, and it will become a high gain screaming monster! "


  1. Thanks for this. I have built several of the other SI tonebender / AKA hot silicon's but not this one.

  2. Do the transistor and resistor on column 17 share a hole? Bodge

    1. that shouldn't be like that. thanks for catching that error, i fixed the layout.

  3. It works. I've skipped the fat switch for now and I'm using 5n2222s and a 4.7nf instead of the 8.2nf. I've not had a major noodle but it has promise. The trimmer could come off board and if combined with a 10-22k starve pot open up some interesting noise options. When i have chance I might switch the 47k for a 470k pot and see what happens there. Thanks for the layouts

  4. Fired up right away. Tonecontroll is working more like a midcontroll on my build, is that the way it should be? Also, in "thin mode" it is veeeeery thin, I upped the 10nf to a 15nf and that was better. Still I feel there should be more twang/edge as in the video.