I powered a discarded HT battery case with a lighter plug and integrated
the tinytrak in the case. The photos and the schematic shown do not agree.
I built it with power being applied to an adapter from DB9 plug and socket
pair and brought the digital interface lines out of the battery case. Then
I had a better idea when I drew the schematic. I reversed the power and the
interface lines by putting power into the battery case and by runing the
interface lines from the adaptor. The interface line is a shielded cable with
two conductors. The PTT line is on the shield and the two wires are the microphone
to the HT and the speaker from the HT.
The advantages are:
Easier operation when not using digital.
Power is removed from tinytrak when not using digital