Does anyone know a good amplifier for Art's minimum theremin?

I know he has a schematic for one online, but if I were to build it for my final project, I would be required to analyze and explain how the amplifier worked as well as the theremin... So does anyone know an amplifier that I could buy, prebuilt and assembled that would work with the minimum theremin? Hopefully it's under $20.

Use computer amplified speakers which are readily available every time someone upgrades. You probably have a set lying around. Avoid any that use an optical input.

Edit-1: For proper theremin behavior you will need to connect the negative side of your theremin to a good earth ground. Often this is achieved through a grounded amplifier input which the computer speakers "will not" provide.

You could make a special plug and use a connecting wire to the wall receptacle earth ground contact. This may be dangerous if you don’t know what you are doing!

Edit-2: If you were set up on a folding metal frame table you might try connecting to the metal frame and use this as a virtual ground. If the whole table is metal set your board on a short non-conductive (12”) pedestal above the table then connect to the metal frame. This is not ideal but workable.
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