THE VOX BOARDS
Here are two different vox circuits,
the first is built with a 2N222A switch for low current
applications, note that the board plugs directly into
the mike socket and draws 4mA from the 5 or 8 volt pin.
Traces on the board route all mike functions such as
up / down , ptt, vcc, ground etc. between mike and radio:
Here is the top of the board:
Here is the bottom: note jumper
Schematic : Modified from N1HFX http://www.rason.org/Projects/basicvox/basicvox.htm
Parts placement:
The copper traces: 80 mm X 50 mm
SECOND VOX BOARD:
This board uses an outboard 9 volt battery and a relay
for higher current applications. It sports a nice sensitivity/gain control and a delay or " hang time " adjustment. Also has an LED to confirm PTT activation. Works very well:
Parts placement with traces showing through:
here is the schematic:
The copper board:
