I have choosen Latch Relays because they are not using power after the shift on or off. Thats brilliant, but what position are they in and how to choose the right way? Well this little circuit that I have made, does the job. It only needs a PTT input to make the right position and you are not in doubt.
How is it made ? The relay has two inputs – one for on and one for off, and only need a short pulse to change it position. My circuit is generating a short pulse for about 35-40 mSek dependent of the input signal and sends it to the right input on the relay. It works very safe and when someone needs to be very safe of the condition – a return signal is also available to control the relay position. I use it in my upper box by the antenna, where my preamp is placed and my Sequencer will not continue the sequence when there is a problem with the antenna relay. So my PA and preamp is protected when something goes wrong.
All relevant files are below for download and it is made with SMD components. Check out my other project, for the Sequencer.