Zeeko:
I'm using a Sainsmart 16 relay module, and relays turn ON when I send LOW voltage signals from my Arduino ports to the control pins on the board.That said, I'm controlling a 12v water valve that uses TWO signals- one to open the valve, and a separate signal to close the valve... It needs two relays that are always doing the opposite thing. I want to conserve a digital pin on my Arduino and do two things at once using a transistor... where if I want water, the opposite signal is sent to the OFF relay.
Can't you use two relay channels for that.
The NO contact of one, and the NC contact of the other one.
AFAIK a 16-channel relay board uses 3.8mA drive current per channel, so you can drive up to 5 channels with one Arduino pin.
Leo..