ST-VOX1 Voice Operated Relay
The voice activated relay unit shall be an RDL ST-VOX1. The unit shall provide two unbalanced audio inputs. One input shall be designated for a mic-level signal and one input shall be designated for a line-level signal. The unit shall detect an audio signal on either input to activate a relay and an open-collector output terminal.

The mic input shall have an input impedance no less than 5 kOhms. The mic input signal detection circuit shall be adjustable to trigger on input signal levels between -80 dBu and -50 dBu. The line input shall have an input impedance of no less than 200 kOhms. The line input signal detection circuit shall be adjustable to trigger on input signal levels between -45 dBu and -15 dBu.

Two continuously adjustable multi-turn trimming controls shall be provided. One trimmer shall be provided to set the sensitivity of the audio detector circuit. A corresponding LED indicator shall be provided to indicate the detection of audio to facilitate proper input sensitivity adjustment. One trimmer shall be provided to set the delay between the end of input signal detection and the release of the relay and open-collector terminals.

The relay contacts available at the terminal block shall be 2 Form C rated to switch 60 W at a current of up to 2 A. The relay shall be a sealed high-reliability type specified to provide more than 1,000,000 operations. The relay contacts shall activate within 5 ms of audio detection.  The open-collector output shall activate within 3 ms of audio detection. The release delay shall be adjustable from 70 to 260 ms for the relay and from 15 to 260 ms for the open-collector. The open collector shall be capable of sinking 25 mA.

Sequential detection activation shall be separated by a nominal duration of 50 ms. 

The unit shall be constructed in an electrically non-conductive, thermally conductive enclosure. Internal circuitry shall be protected from moisture and vibration using a thermally conductive compound that permanently secures the circuitry within the enclosure.

The face of the unit shall provide graphical labels identifying wiring connections and operating controls. Indicators and controls shall be oriented toward the front edge of the unit.

Connection to external wiring shall be provided using a fixed terminal block on the edge of the unit. The terminal block shall accept wiring gauges from 14 to 22 and shall include a positive electrically conductive mechanism to prevent wire abrasion by the terminal screws.

The unit shall measure 3” (7.6 cm) x 1.6” (4 cm) x 0.7” (1.7 cm) and be compatible with all RDL STICK-ON mounting accessories. The unit shall be supplied with a two part re-closable polypropylene fastener system equipped with a rubber adhesive that bonds to low surface energy materials.

Power requirements shall be 24 Vdc ground-referenced with a maximum current not exceeding 30 mA with no connection to the open-collector slave output terminal or 50 mA with a 20 mA load between the open-collector slave output terminal and the power supply. The unit shall utilize an external power supply. The unit shall be engineered, assembled and tested in the U.S.A. and be specified for continuous duty in professional installed systems. The unit shall be specified for operation in an ambient temperature between 0 and 55 degrees C. The unit shall comply with relevant EMC requirements and shall bear the CE marking.

The unit shall be an RDL ST-VOX1.