I am using a secu16 to determine when the mail comes. The mailbox has an IR TX RX pair, but I cannot get the secu to recognize the change in voltage. I had this working before so I cannot figure out why it's not working now.
I am using a potentiometer to bring down 18V to 5V, the 5V are applied to the IR transmitter with resistance as a current limiter. The same 5V are used fro the receiver. When there is no mail the voltage is 0 (zero) when there is mail the voltage is about 2V so the detector is working. When I attach the leads to the secu16, I read 4V on the secu16 terminal no matter what. If I just go directly from the potentiometer to the secu16, I can see it change state at about 1.5V, but it will never change state when attaching the leads from the IR receiver.
What am I missing?