Step 5: Sound
Warning: This step required opening up the case of some old cheap computer speakers. Mains voltage is inside and care should be taken.
You could make your own amplifier circuit but this was an easy way out. Find an old set of computer speakers. The amplifier circuit inside has everything we need already.
The transformer on the left is taking mains voltage and providing 9V AC to the circuit board. This is safely enclosed inside the coffee table. Never touch the transformer when power is turned on.The volume pot is removed from the circuit board and hard wired with 2 resistors to be the equivalent to being in the max volume position. Volume will be adjusted from the pi. The mini stereo socket is mounted down into the bottom cover. The circuit bypasses the speaker when headphones are plugged in.