With the reference to the comparator between R13,R14 can I assume that the voltage there is always approx 18% of the supply voltage so it should not matter as long as it is always proportional as well as R5, R6 ?
As for R4, C7 what is the calculation to find the best values?
I have tested with using the 7809 reg and I get:
1.6V at pin 3 of U5
4.4V at pin 3 of U3
128 mV across Rx
I switched to a 9V plug in adapter and my values are now:
16V from the adapter's main at no load
10.4V with load (my circuit)
2.8V at pin 3 of U5
7.8V at pin 3 of U3
80 mV across Rx
I seam to be getting the same range from the Rx using both ways.
Another concern, if I want to mass produce my circuit, can I trust that each adapter perform the same or close enough?
Mike