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Radio Design Labs   |   Flat Pack Series   |   Remote Level Control  Series   |   Rack Up Series   |   ST-ACR1 thru ST-HP3   |    ST-MX2 thru ST-MPA2   |   ST-NG1 thru ST-SH2   |   ST-SSR1 thru ST-VVCA2   |   STA-1 Thru STD-600   |   STM-1 Thru STP-1   |   TX-10B Thru TX-VLA1
ST-SSR1 Solid-State "Relay" Audio Switch
To Switch Line-Level Sources
To Select Between Two Balanced Lines
Silent Audio Switching
Audio Switching for Audio Muting
Fast Switching for Audio Muting
Switching by Open Collector Logic
APPLICATION: The ST-SSR1 is part of a group of products in the "STICK-ON" series from Radio Design Labs. The durable bottom adhesive permits quick, permanent mounting nearly anywhere, or use it with RDL's racking accessories. The ST-SSR1 offers the ultimate in totally solid state audio switching, with the big can put it right where you need it!
FUNCTIONAL DESCRIPTION: The ST-SSR1 has two line level audio inputs and a single line level audio output. In the absence of a control input, the "NORMAL" input feeds the module output. When the "TRIG" control terminal is pulled to ground, the "SELECT" input is switched to the output and the "NORMAL" output is switched off. When the "TRIG" terminal is again allowed to go HI, then the "SELECT" input is turned off and the "NORMAL" input is switched to the output. The module contains no mechanical relay. The audio inputs are applied to a low-noise preamplifier. The control circuits utilize solid state switching to apply either of these signals to a balanced line driver.
The ST-SSR1 has user-selectable switching rates. The module can be used in muting applications where audio must be switched off extremely fast. This could be required to prevent feedback in automatic microphone mixing installations. For muting, typically, an input would only be connected to the "NORMAL" input, and the ST-SSR1 would be used to turn this line "off". In this mode, the audio "off-time" switching is accomplished in 10µ. Although necessary in some circumstances, this fast a switching transition can appear harsh to the ear and would be undesirable where the module is being used to select inputs to a high power amplifier or in high quality studio applications. Installation of a jumper between the "SOFT" terminal and "GROUND" slows the switching transition by implementing a soft knee and ramping the audio to the "on" or "off" condition. This still sounds INSTANT to the ear, but is slowed sufficiently to remove any unpleasant edge from the switch transition. For most applications, the module is used in the "SOFT" mode.
The control current required at the "TRIG" terminal is so minimal (0.5 mA) that the ST-SSR1 can be controlled from nearly any source...from switches to logic circuits. The "TRIG" input feeds a comparator which switches with a threshold of 2 volts, permitting open-collector switching, or switching directly from circuits operating from a 5 volt supply!
The exceptional low noise and low distortion performance of the ST-SSR1 makes it the ideal choice for noiseless line-level audio switching in both sound system or recording installations. Used in conjunction with other STICK-ON audio and control modules, the ST-SSR1 can be the foundation for many high quality, innovative audio systems!
ST-TC1 Telephone System Coupler
To Simulate a Telco CO Line
To Add Radio Control or Paging to (KSU)
Contact Closure when Line is Selected
Audio Input/Output from Telephone Switching Unit
Switching Unit
APPLICATION: The ST-TC1 is intended to be connected to an on-site telephone system switching unit KSU. It is NOT intended to be connected directly to a telephone CO line. Connections from the ST-TC1 go into the telephone switching unit as if the ST-TC1 was an incoming phone line.
When the KSU seizes the line to the ST-TC1, a relay contact closure is provided which can be used to control a variety of equipment, such as a paging system or radio system. The closure is maintained as long as the line is seized. A 600 Ohm transformer-isolated audio feed is available for audio to or from the telephone switching unit. The ST-TC1 will pass DTMF audio from a telephone keypad or other DTMF generating device.
The ST-TC1 may be utilized to add paging zones or a radio system interface to a telephone system. When any instrument in the telephone system "picks up" the line associated with the ST-TC1, the relay closes to activate the radio or paging function, and the audio spoken into the handset is broadcast. The ST-TC1 can not be connected to a phone line that has ringer voltage present.
The ST-TC1 can be used in conjunction with RDL's ST-VOX1 modules to provide two-way communication. The ST-VOX1 will provide the necessary Push-to-Talk function to key the two-way communications systems.

ST-UBA2 Unbalanced to Balanced Amplifier

Anywhere you need...
To Convert Stereo IHF Levels to Stereo PRO
Additional Summed MONO OUT
Independently Adjustable Gain
Ground-Referenced Conversion Module
Dual-LED VU Metering for Each Channel Included
Unparalleled Audio Performance
The ST-UBA2 is used in any application requiring conversion from unbalanced consumer format signals to professional +4 dBu. It may be used to balance audio from CD players, cassette decks, computer sound cards, televisions, and a wide variety of other unbalanced sources. The mono sum output may be used to drive patch-bay jacks, monitors or subwoofer amplifiers.

Separate Dual-LED VU metering is provided for the left and right outputs. A green LED illuminates at 15 dB below +4 dBu. The intensity of the green LED progresses from minimum at -11 dBu to full intensity at +4 dBu. The adjacent red LED illuminates at +4 dBu.

The audio clarity, low-noise, low-distortion and excellent crosstalk performance makes this module ideally suited to a wide variety of demanding audio applications. Use this module in conjunction with other RDL® modules as part of a high quality, flexible audio/ video system.

ST-UMX3 Universal Audio Mixer
Anywhere you need...
Audio Mixing with Up To Three Inputs
Switch-Selectable Mic or Line Inputs
Switch-Selectable Mic or Line Output
To Add Additional Microphone or Line Level Inputs
to an Existing Mixer
To Combine Signals of Different Level, Impedance,
or Balanced /Unbalanced Configuration
The ST-UMX3 is a three-channel audio mixer for combining mic-level or line-level signals to a single output. A MIC/LINE switch is provided for each input. A separate MIC/ LINE switch selects the output level. Each input features a separate preamplifier circuit, which isolates it from the other inputs. An audio taper single turn gain adjustment is provided for each of the three input preamps. Signals from the three preamps are actively summed and fed to the output amplifier which includes an RDL® dual-LED VU meter.

Each input level is set while observing the LED output level meter. The dual-LED output meter follows standard VU ballistics. The intensity of the green LED progresses from minimum at -11 dBu to full intensity at +4 dBu.

The flexibility of switching each input and the output between MIC or LINE allows installers to address a wide variety of mixing solutions with only one product type.

ST-VCA2 Voltage Controlled Amplifier
Audio Level Control from a DC Voltage
Audio Level Remote Control
Two or Three Wire DC Control
VCA with Microphone or Line Level Input
VCA with Line Level Output
VCA with LED Metering of Operating Level
APPLICATION: The ST-VCA2 is used in applications requiring smooth audio level control from a remote control panel, potentiometer or dc voltage (0 to 10 V). Installation in series with the audio input of a power amplifier allows remote control of that amplifier’s level. For installations where it is preferred to keep the audio localized in the rack, audio controls are extended outside the rack from the ST-VCA2. Many installations benefit from avoiding long-term potentiometer wear from audio running through the potentiometer. An ST-VCA2 with external dc control provides virtual immunity from “scratchy” audio. Audio/video system control units often provide 0 to 10 Vdc control outputs that can directly control audio levels using an ST-VCA2. The ST-VCA2 is primarily intended for line level attenuation; a high quality utility microphone preamplifier is included in the module. If remote control of a microphone preamplifier is desired, such as a wall mounted level control for a microphone jack, the ST-VCA2 may serve as a remote controlled microphone preamplifier.

ST-VP1 Voice-Over / Paging Module

Anywhere you need...
High-Quality Voice-Over Mixing
Noiseless Paging
A Single Input Adapted for Paging or Voice-Over
Selectable Fade-Under or Hard-Cut
Adjustable Fade DEPTH and RATE
Soft Audio Switching
The ST-VP1 is intended for voice-over paging with user adjusted and controlled FADE or CUT between two input sources. This unit is also perfect for voice-overs where precise and consistent fade levels are required. Automatic operation can be achieved when used in conjuction with RDL’s® ST-ACR products.

Typical Performance reflects product at publication time exclusive of EMC data, if any, supplied with product. Specifications subject to change without notice.
RDL, Radio Design Labs, the Radio Design Labs logo, STICK-ON, Rack-Up and the Rack-Up logo are registered trademarks of Radio Design Labs. TX, Flat-Pak, SourceFlex, Sure-Lok and Specialists in Practical Precision Engineering are trademarks of Radio Design Labs.
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The products shown above are typically stocked by "You-do-it" Electronics Center. We try to maintain a current listing of products available. Occasionally products which are out of production may be listed on our website.
Please E-mail or Call for current availability. Prices are subject to change without notice. All orders are subject to acceptance by this company & our Vendor in accordance with its standard acknowledgement form. All prices are subject to all applicable State and/or Local sales taxes. Terms are MasterCard, Visa, Discover, or American Express or Check with order, unless other arrangements are made with our credit department.
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