Portsdown 4 sequencer

[Rishtonite]

Am I correct in thinking the following would work...
GPIO pin 40 feeds the LED of optoisolator (standard or darlington?) and the output arrangement is like the attached screen grab,
but with 12v, not 24v, and (in the image) the motor is replaced by a small SPDT relay which is connected to act like the TX/RX switch in the G8ADE
sequencer circuit (CQ-TV 125)

[gm1mfn]

That circuit is more complicated than necessary and lacking a vital component. A relay is an inductive device and there should be a reverse diode across the coil to dump the back-EMF when switching off.

This is what you should use:

[Rishtonite]

Thanks for the comments and new diagram. After posting I did think more about it and realised it wasn't the best solution.
Is "V in" straight from pin 40, no opto ??

[radiogareth]

Yes, that's right, via the 1k resistor. Its what I use for my 'PTT' control, both Portsdown and Langstone have a 100mSec delay after making that pin high before any RF is emitted.
Gareth