- U1 socket - DIP-8
- J3 - 0.1 inch right-angle header
- C1, C2, C3, C4, C5 - 100 nF (see note below)
- R3, R6, R8, R9 - 10 kΩ
- R4 - 22 kΩ
- R5 - 47 kΩ
- R7 - 1 kΩ
- Q1, Q2 - 2N4401
- J1, J2 - 3.5 mm TRS jack
- S1, S2, S3 - Momentary tactile switches
- SP1 - Piezo speaker (see note below)
- SW1 - Power switch
- BT1 - CR2032 battery holder (see note below)
- U1 - ATtiny85V
- I recommend using some flux on the pads for Q1 and Q2 before soldering. They are pretty close together and this will help to prevent solder bridges.
- The C1 footprint is for a polarized electrolytic cap, but I changed it to a 100 nF ceramic.
- Make sure you solder the batter holder so that the battery can slide in from the nearest edge of the PCB, and will stop when hitting the tabs folded down on the edge closest to the center of the PCB.
- The piezo buzzer is polarized but I don't have a marking on the PCB silkscreen to indicate polarity. Please make sure that the positive terminal of the piezo element is on the side nearest C1 and R7.
- Make sure that power is applied before attempting the firmware update
- Power swtich protudes too far
- The piezo volume pot is pretty ineffective, and most likely will be left at full volume. It will probably be removed in the next board spin.