12-13-2017, 02:09 PM
I got up dark and early this morning and built a switch. It's the circuit on the right.
https://imgur.com/a/6t8oz
The big chip up top is a switch array. It contains 64 electronically controlled switches in an 8x8 matrix. This will be used to connect the audio inputs and outputs of the telephone interfaces to establish calls. It'll handle 4 simultaneous calls.
The microcontroller at bottom right and the voltage regulator circuit at bottom left are the same as for the call progress tone generator (left).
Although it looks like a mess of wires, this circuit is simpler than the tone generator. There were a metric shit ton of bias resistors to solder, but it proved to be less of a pain than I thought it would be. I made a few gaffes and blunders while building it, all easily recovered.
https://imgur.com/a/6t8oz
The big chip up top is a switch array. It contains 64 electronically controlled switches in an 8x8 matrix. This will be used to connect the audio inputs and outputs of the telephone interfaces to establish calls. It'll handle 4 simultaneous calls.
The microcontroller at bottom right and the voltage regulator circuit at bottom left are the same as for the call progress tone generator (left).
Although it looks like a mess of wires, this circuit is simpler than the tone generator. There were a metric shit ton of bias resistors to solder, but it proved to be less of a pain than I thought it would be. I made a few gaffes and blunders while building it, all easily recovered.
