Hello, I'm LyfeOnEdge.
I'm working on a personal project, a bluetooth solution for rotary phones, inspired by this retired SparkFun Project: https://www.sparkfun.com/products/retired/9803
Much of the original schematic is being kept, however it is to be powered by a 7.4V cell with a buck converter for efficiency instead of a linear regulator.
Due to size constraints the board is being modularized into several parts:
Main board with atmega8 and WT32, mic filter, dial tone filter, and icsp header.
My question is if there are any good pre-existing solutions for producing the AC ring voltage from the 3V3 already used by the ATMEGA8 and WT32, or if I'm better off using the circuit already used in the original schematic.
I'm looking for a 2 wires in (Power and ground, delivered and switched by the main board) two wires out (fed to the ringer) solution.