Line-Level Audio Controlled Relay - 5 to 50 s delay

  • Switching Controlled by Audio Signal
  • Sensing of Line-Level Signal
  • Silence Sensing
  • DPDT Switching Contacts
  • Open-Collector SLAVE Output
Recommended Power Supply ( Not Included )
PS-24AS (USA)PS-24AX (International)


The ST-ACR2 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-ACR2 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-ACR2 is from 5 seconds to 50 seconds.


Audio Input:10 kΩ balanced bridging
Input Connections:May be connected balanced or unbalanced
Control Output: Open-collector @ 25 mA suitable to drive indicators or slave LCR relay
Indicators:Audio threshold LED (for setting sensitivity)
Retrigger Delay:250 ms
Max. Switching Power:60 W, 125 VA
Max. Switching Voltage:220 Vdc, 250 Vac
Max. Switching Current:2 A
Activation Response Time:25 ms
Input Sensitivity:-30 dBu to 0 dBu (adjustable)
Relay Release Delay:5 sec. to 50 sec. nominal (adjustable)
Ambient Operating Environment:0° C to 55° C
Power RequirementGROUND-REFERENCED, 24 Vdc @ 50 mA*
* Assumes 20 mA max load at SLAVE output
Dimensions:Height: 0.7 in. (1.7 cm), Width: 3 in. (7.6 cm), Depth: 1.6 in. (3.9 cm)
Package Type:Cardboard Box
Tariff code:8543.70.9860
WEEE weight:0.15 lbs.
Shipping Weight:0.2 lbs.
Package Dimensions:2 x 2 x 4 in.

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CAD FilesUnitsFormat
Engineering Functional BlockAmericanDXF
Panel Diagram - FrontAmericanDXF
Panel Diagram - FrontMetricDXF
High Res ImagesFormat
Declaration of Conformity


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