LM373 Transmit Block Wiring
One of the major problems I have when I try to document projects is that I know how they are wired without even looking at a schematic. The problem is that the reader is not in my head so I need to do a better job on full documentation. Here is another magic decoder ring for this project.
There was a bit of confusion about the two 2N3904 amplifiers on the one board and how were they hooked up into the circuit. In the bi-directional amp stage write up I mentioned that one variant of this board had three relays so that the board was in effect in a bilateral mode when connected to other circuit elements. In this build it is used as two separate circuits resting on a common board. Hopefully the pictorial below will clear up that mystery.