Annunciator DIM/Test Unit

Solid State, Two Channel, FAA and TSO approved.

The Annunciator Dim/Test Unit (ADU) simplifies the engineering task of installing aircraft system annunciators.  It provides a dedicated source of adjustable dimming, power, and testing for both pilot and copilot annunciators in one compact unit.

The ADU houses two separate P.C. boards that are identical but independent from each other, including separate annunciator power sources.  Each P.C. board contains 25 diode isolated annunciator trigger / test lines, for +28vdc logic (normally set to +14VDC), and one adjustable dimming circuit for ground logic. These adjustable circuits eliminate a common problem encountered in major avionics installation, namely matching the intensity of all the annunciators during a night light condition.

The Bright / Dim and Test mode functions are designed to ease installation and are triggered by either +28VDC or ground logic.



Annunciator power is supplied from the a +28VDC circuit breaker through a normally closed relay contact. Selecting Dim mode routes annunciator power through a variable power circuit capable of supplying +28vdc to +10VDC (factory set to +14VDC).  Power from this circuit then travels to seven diode isolated power outputs.  Total current draw from this circuit should not exceed 1.5 Amps at +28VDC.

Each board contains an adjustable ground potential circuit for dimming 28 VDC annunciators. During normal operation (bright light) a ground is supplied through a normally closed relay contact.  Selection of Dim mode routes ground potential through a variable regulator circuit, adjustable from +0.0VDC to +18VDC (also factory set to +14VDC).  Total current draw on this circuit is limited to 0.5 amps at +28VDC. Each board also contains 25 diode isolated input/output lines that are either grounded or supplied +28VDC during annunciator test mode. Configuration of these test lines is dependent upon the dash number of the unit.



DO-160C Categories Qualified:


Altitude: 50,000 ft

Temperature: -55 C to +85 C

Power Requirements

2.0 amps at +28.0 VDC

per channel (2 each)

 FAA Approved - TSO C71



Mating Connector



1/4 ATR Dwarf Box


2.0 lbs



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