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GemToasterAmp

9v to 12v Battery Powered Amp

LM386 Based power amp with JFET Preamp

  • Quality of sound highly dependent on speaker & cab combo.

3D Model

Iso

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Underside

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Topside

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PCB Layout

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Schematic

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JFET Selection

I thought there were some notes on this but I can't find them, the only other thing I had read says "Anything Goes". They used cheapo out of spec parts and they worked.

Other Parts slection

Some parts can be more difficult to find or I just didnt have them in stock for my test build, so these are the values I used in my working build:

3.9k Resistors - 15k in parallel with 5.1k 4.3k Resistors - 15k in parallel with 6.2k

470n Capacitor - 390n Could put an additional 100n in parallel to get closer to marked value

15n Capacitor - 22n

Revision 0 Issues:

  • Power Amp control is backwards, but this control isnt that useable, on the origional project this was replaced with a trimpot anyway, so suggest mounting it back to front for a "set and forget" control, or replace with fixed value resistor.
    • Could also look into cutting traces between 2 and 3 - TODO