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Monday, 15 August 2016

Tone Factor Cream Pie

A small Germanium Booster/OD.

Original using NPN Germanium Transistors.


Since PNP Germaniums are more readily available, cheaper, and reliable here's a PNP version. Remember you can NOT daisy chain this with NPN devices.



And here's a layout that's a touch larger, but includes an onboard inverter to give you the ability to daisy chain it.


Suggested hfe for the transistors is between 90-120hfe. The trimmer is used to set the collector voltage. Suggested between 3-5V, with a lower voltage giving a dirtier boost. You can replace it with an offboard pot to allow for on the fly adjusting, like the layout below.


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12 comments:

  1. Velouria FX15 August 2016 at 14:55

    Hi. First, thanks for this layout, I love germanium ODs. Can i use the third layout with charge pump and use a bias pot wiring the pot in the same position of the trimmer? Sorry my poor english.

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    1. Zach15 August 2016 at 19:06

      you should be able to. just put the bias pot in like the bottom layout and you should be good to go.

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    2. Velouria FX15 August 2016 at 23:20

      thanks for answer, i'll try this in weekend

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  2. Unknown15 August 2016 at 20:46

    Looks fun... Can you verify cuts in each layout? Seems to be some discrepancy. Thanks for all the great work you do!!

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    Replies
    1. Zach15 August 2016 at 23:50

      if you're talking about the cut under the trimmer, it's not really a discrepancy, cause tbh it's not really needed. it was left there after moving stuff around and was needed at one point. i'll make the change to the boards so it's not confusing.

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    2. Unknown16 August 2016 at 05:27

      It was no issue for me, (all of them said 3 cuts, one was 5 one was 2 and one was 3) just wanted to clear it up for any future visitors :) Pretty cool little boost. The NPN version is verified. Tone pot seems to have most of it's usable range at the end of it's clockwise turn...will play with that a bit...otherwise smooth OD. Thanks again. Have a great day!

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    3. Zach16 August 2016 at 06:18

      great. thanks for verifying. you could always play with the input cap(10nF) and the tone cap (100nF) to change the frequencies affected.

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  3. Unknown22 August 2016 at 22:52

    would a 2n2222a work in the #1 build?

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  4. Squirrels25 August 2016 at 20:04

    Sounds great with a 2N1304a with a gain around 55.

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  5. dickramone27 September 2016 at 21:17

    dumb question from a new builder here, but where is the board output for me to connect the footswitch?

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    Replies
    1. Zach28 September 2016 at 01:39

      every layout will state in the build notes on the bottom where things go that aren't mentioned on the board, and/or do not have wires directly on the board. in most cases it's lug 2 of the volume pot.

      it appears that the notes got cut off, and didn't notice since it's been verified. i'll have to go back to change the spacing and make sure they're there.

      since the notes are MIA remember lug 1 of the volume pot goes to ground.

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    2. dickramone28 September 2016 at 02:26

      thank you, Zach, that's very helpful!

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