pull up resistor relay
Hi and thanks for looking into the attached diagram.
On the left side (green) is a digital downcounter board. The output is open collector, normally high and goes (and stays) low when the counter reaches zero.
On the right side (yellow) is a relay driver board.
The relay must be activated while the counter runs and disactivated when the counter reaches zero.
- Did I choose the right input (rising flank)?
- What is the best value for the pullup resistor Rp? I thought around 1K/.5W, but I'd like to ask you how to find the right value, not by trying but by looking into the diagram.