RDL ST-ACR1M Specifications

STICK-ON® SERIES

Model ST-ACR Series
Audio Controlled Relay

ANYWHERE YOU NEED...

• Control Switching from Audio Signal

• Switching from Mic OR Line Signals

• Silence Sensing

• Precise Threshold Adjustment

• DPDT Switching Contacts

• Open-Collector Slave Output

You Need The ST-ACR Series!

APPLICATION: Each of the ST-ACR products is an Audio Controlled Relay in the group of STICK-ON
Series products by Radio Design Labs. These products are designed for quick convenient installation, and
reliable operation in a variety of control applications.

THREE MODELS TO FIT SPECIFIC APPLICATIONS:
ST-ACR1 This module is designed to switch on line-level sources. Its relatively short release delay time

makes it the optimum choice for voice applications.
ST-ACR1M This module is designed to switch on low-level sources, such as microphones or mic-level

sources. Its relatively short release delay time makes it the optimum choice for voice applications where
the source has not been pre-amped up to a line level.

ST-ACR2 This module is designed to switch on line-level sources, and has a longer release delay time
making it the optimum choice for most music applications. The ST-ACR2 is widely used as a Silence
Sensor.

FEATURES IN COMMON TO ALL ACR PRODUCTS:

• 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 open-collector terminal allows additional relays to be added for more contacts

(RDL’s ST-LCR1 or ST-LCR2)

• 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

All this is available in the unbelievable compactness and convenience of the RDL STICK-ONs. Put them
right where you need them, or design them in with our optional racking kits. Anytime you need DPDT
contact closures controlled by ANY audio source, your simple, cost-effective solution is found in the
ST-ACR product group! Use the ST-ACR’s combined with other RDL RACK-UP®, STICK-ON, TX™, or
FLAT-PAK™ series products as part of a complete audio/video system.

RDL •• P.O. Box 1286 •• Carpinteria, CA., USA 93014 •• [phone] •• FAX [phone] •• http://www.rdlnet.com

STICK-ON® SERIES

Model ST-ACR Series
Audio Controlled Relay

Installation/Operation

EN55103-1 E1-E5; EN55103-2 E1-E4

Typical Performance reflects product at publication time
exclusive of EMC data, if any, supplied with product.
Specifications are subject to change without notice.

TYPICAL PERFORMANCE

ST-ACR1:
Input Sensitivity: -30 dBu to 0 dBu, (adjustable, provides

Relay Release Delay: 0.5 to 5.0 seconds
(Multi-turn adjustable)
ST-ACR1M:
Input Sensitivity: -60 dBu to -30 dBu, (adjustable,provides

Relay Release Delay: 0.5 to 5.0 seconds
(Multi-turn adjustable)
ST-ACR2:
Input Sensitivity: -30 dBu to 0 dBu (adjustable, provides

Relay Release Delay: 5.0 to 50.0 seconds
(Multi-turn adjustable)

891-0031I

switching at a -20 dB threshold for
signals of -10 dBu to +20 dBu)

switching at a -20 dB threshold for
signals of -40 dBu to -10 dBu)

switching at a -20 dB threshold for
signals of -10 dBu to +20 dBu)

Radio Design Labs Technical Support Centers

U.S.A. [phone], [phone]; Fax: [phone]

Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287

COMMON TO ALL ST-ACRs:
Audio Input: 10 kΩ balanced bridging

Input Connections: Balanced or unbalanced
Control Output: Open-collector @ 100 mA
Suitable to drive indicators
or slave LCR
Relay Contacts: Double-Pole/Double-Throw
Max. Switching Power: 60 W, 125 VA
Max. Switching Voltage: 220, 250 Vdc
Max. Switching Current: 2 A
Max. Carrying Current: 3 A
Power Requirement: 24 to 33 Vdc @ 50 mA
Ground-referenced
Dimensions: Height: 1.55 in. 3.94 cm

Width: 3.00 in. 7.62 cm
Depth: 0.65 in. 1.65 cm