VAR1 Voice-Activated Relay is a DPDT relay device that is activated when an audio signal is detected at the microphone pre-amp or at 70V, 25V, or 600-ohm line level inputs. It has a number of useful applications, such as muting a sound system in response to a microphone or telephone page, activation of accessory (security) equipment, or activation of a zone paging module. A slide switch is included to select the pre-amp or the line inputs. The VOX detect circuit also includes volume, sensitivity, and delay controls.The audio output is an isolated 600-ohm transformer.The unit operates from a DC power source (not included). Features: 2 sets of C-Form (N.O. & N.C.) relay contacts respond to audio activity. 4 levels of input signals: microphone, 600-ohm line, 25V, & 70V speaker systems. Built-in balanced, low noise, high gain microphone pre-amp. A transformer-isolated, 600-ohm small signal level output of detected audio available. Trigger threshold adjustment.