The TX-PCR1 is the ideal choice in many applications where switching needs to be controlled from a constant-voltage amplified audio source. The module will trigger on any program material, with paging sources being the most common. The TX-PCR1 includes both an open-collector SLAVE output to control other modules or equipment and a DPDT high power switching relay suited to switching speaker loads. The amplified audio source is connected using a detachable terminal block. A front-panel switch is provided to select the source type: 25 V, 70 V or 100 V. The 25 V setting may be used for an 8 ohm, 75 Watt maximum, amplified source. Input sensitivity is adjusted on a single-turn trimmer. In the clockwise position, the SENSITIVITY trigger threshold is 30 dB below the switch-selected constant voltage. A red LED illuminates whenever the audio level exceeds the trigger threshold, facilitating the sensitivity adjustment.