Detecting a voltage without actual connecting

Thread Starter

Robin Gerritsen

Joined May 25, 2016
I thought you couldn't connect anything to the doorbell?
I think when I want it to work without connecting the wires to the doorbell, it will take more time to get it to work, than just connecting it.

The HA11AA1 would do the job. Connect the input with a 390Ω resistor in series across the bell, and then use a 10kΩ pull-up resistor to +5V to get your logic output signal.
Is it possible to get 3.3v? Or do I need a voltage divider to get this signal?