I have a fairly advanced power switch that is a commercial product. How it works is not particularly important, but what happens is that the user supplies it with power, and when it decides to be "off" the two output lines are disconnected, but when "on" the two input lines feed the output. kinda like one of those wall-socket timer products, i imagine (tho obviously those are AC while this is dc)
The issue is that I need to power a second item in this compartment. It would also be highly beneficial to power this second item using a second battery, but i would love to interface with a single switch. If the commercial product simply had a second set of input/output pins i would be done! alas it does not.
Also noteworthy is that the whole compartment will be subject to some fairly strong forces and vibrations. think flying robot / combat drone action. There is not much harm in the devices being left on a bit longer than intended - so, here is what I am thinking - some kind of SSR controlled both with the first switch and 555 timer, so the circuit would stay on for some 5min or other hardcoded value if the first switch turned off. if the first switch turned back on within the hardcoded window, the second would not turn off at all.
I have the parts and the idea but I am not sure how to put it all together! Thakns for any help.