Yes,
here i post a drawing of the simple circuit i have assembled.
The purpose is to supply a square wave or other signal, time controlled (with very long on /off duty cycle),
to a simple counter (the DUT) that i need to test in these conditions.
I apologize for the hand written drawing, i do it now, whlie i listen to the clicks of the bistable rele' Finder 26.01.
The same job, should be carried on by an optocoupler (an opto-triac) in place of the rele', and in a second time i will modify
the circuit: now i need to see if it works or not, and the rele' was ready available.
All this "benchtest" is possible thanks to your Serial_Ringer.
The on period i used is 1sec (on=1000) and the off should be 15min so off=900000 so the rele' should not be stressed so much,
in any case i think will be replaced with an optocoupler or similar component.
So the DUT is driven for 15min with the square wave generator and for 15min no.
The timing is not required to be very very precise, but these long periods of time are difficult to obtain in the analog world.
And programming is not my craft (til now).