Capacitor help please (vintage phone)

Other Hardware General Electronics
58

Thanks for that project. I think I should be able to build that. A couple of questions:

  • I have a few ATtiny85 (with a USB connector) I would want to use for this. In my scenario I have 5V USB power so I don't need the battery solution nor the load switch/deep sleep functionality. Even though the ATtiny85 has only 5 I/O ports this should work as we only need d0, d1 and d2 to operate the H-bridge and d5 for the switch; did I understand the code correctly?
  • What's the ICSP header used for?
  • What's RX (d8)/TX (d9) used?
  • In the schematic HV_OUT1 and HV_OUT2 presumably go to the lead of the rotary phone which has 3 wires. Which two are used to activate the ringer?