How to handle a circuit switched by ground

Other Hardware General Electronics
19

Confirm assumed internal configuration of speaker boxes first:

  1. Connect 5VDC wall wart outputs to the power terminals (VCC and GND) of the speaker box.
  2. Measure voltage from -speaker to GND
    a) should be nearly Vcc when button is not pressed
    b) should be nearly GND when button is pressed (will probably be 0.5V or so).

If you confirm those measurements, then just connect -speaker to an Arduino digital input pin. Signal will go low when button is pressed, but will otherwise be read as high.

Jim

PS - don't disconnect the speakers unless you put load resistors (10K maybe) in their places. Otherwise you will short Vcc directly to GND when a button is pressed.

EDIT -- Oops, did not see before I posted that Mike had already responded with an identical suggestion.