Consult the README on the project repo for programming and operating instructions.
- U1 socket - DIP-8
- J3 - 0.1 inch right-angle header
- C2, C3, C4, C5 - 100 nF
- C1 - 1 μF
- R3, R6, R8, R9 - 10 kΩ
- R4 - 22 kΩ
- R5 - 47 kΩ
- R7 - 1 kΩ
- R2 - 10 kΩ trim pot
- 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
- R10 - 1 MΩ pot
- 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.
- Make sure you solder the battery 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.
- The case screws are M3 and require a 2 mm hex driver for installation.
- Make sure that power is applied before attempting the firmware update.
- Consult the instructions at the bottom of the README on this page. See the image at the top of the page for the layout of the pins on the UART port.
- 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.
- You should use a 3.5 mm stereo cable for the key line, since the way that the key jack is currenlty wired it will not work correctly with a mono cable.