Sound Technology

ST-ACR1

Line-Level Audio Controlled Relay - 0.5 to 5 s

The ST-ACR1 is an Audio Controlled Relay in the STICK-ON® series. These products are designed for quick, convenient installation, and reliable operation in a variety of control applications. The ST-ACR1 is designed to switch on line level sources.

Two multiturn trimmers are provided. The SENS potentiometer adjusts the audio input sensitivity. A threshold LED facilitates accurate adjustment. The module can be set to trigger on signals between -30 dBu and 0 dBu. The DELAY control sets the time required for the relay to release when the audio drops below the threshold.

The delay adjustment range for the ST-ACR1 is from 0.5 seconds to 5 seconds.

Power RequirementsGROUND-REFERENCED, 24 Vdc @ 50 mA* * Assumes 20 mA max load at SLAVE output
Ambient Operating Environment0° C to 55° C
Relay Release Delay0.5 sec. to 5.0 sec. nominal (adjustable)
Input Sensitivity-30 dBu to 0 dBu (adjustable)
Activation Response Time25 ms
Max. Switching Current2 A
Max. Switching Voltage220 Vdc, 250 Vac
Max. Switching Power60 W, 125 VA
ContactsDouble-pole-double-throw
Retrigger Delay250 ms
IndicatorsAudio threshold LED (for setting sensitivity)
Input ConnectionsMay be connected balanced or unbalanced
Control OutputOpen-collector @ 25 mA suitable to drive indicators or slave LCR relay
Audio Input10 kΩ balanced bridging
DimensionsHeight: 0.7 in. (1.7 cm), Width: 3 in. (7.6 cm), Depth: 1.6 in. (3.9 cm)
Package TypeCardboard Box
WEEE weight0.15 lbs.
Shipping Weight0.2 lbs.
Tariff code8543.70.9860
Package Dimensions2 x 2 x 4 in.
  • Switching Controlled by Audio Signal
  • Sensing of Line-Level Signal
  • Silence Sensing
  • DPDT Switching Contacts
  • Open-Collector SLAVE Output
  • High-impedance bridging input connects across any audio line
  • Input may be connected to either balanced or unbalanced sources
  • Multi-turn sensitivity adjustment permits precise threshold setting
  • Multi-turn DELAY control adjusts relay release delay
  • Band-pass filtering yields triggering on characteristic audio spectrum
  • SLAVE terminal may also be used to trigger the control inputs on various other RDL Modules
  • SLAVE terminal may be used with remote switch to manually override the control circuit and turn on the relay
  • SLAVE open-collector terminal allows additional relays to be added for more contacts
    (RDL’s ST-LCR1 or ST-LCR2)