Contact Closure Sensor - This product detects the open-and-closed status of a pair of isolated contacts or the state of open collector devices. - Ideal for detecting contact closure from relays, switches and bush buttons. Can also be employed to determine the state of open collector devices used on digital controllers and current sensors - De-bounce logic is provided to prevent multiply false signals created by contact bounce. A contact or switch must be closed = 3mS before an output is indicated. A contact must remain open for = 50mS before an output is not indicated. This asymmetric reaction time provides fast indication of a contact closure while filtering out subsequence contact chatter or bounce. - Power supply is not required when used w/ the GC-100. - Cable/Connector - 1,8 m, 3.5mm stereo plug.