associated with each Model 46 interface. In these applications one might want to view the Model 46 as providing four 2-wire-to-4-wire interface circuits. The Model 46 can certainly be used in this fashion, but adapter cables will have to be prepared. These adapters will “split” the Model 46’s 2-wire PL intercom connectors into two 3-pin male XLR connectors, one for each audio channel. Pin 1 of the female 3-pin XLR intended to mate with the Model 46 will connect to pin 1 of both 3-pin male XLR connectors. Pin 2 of the female XLR will go to pin 3 of the male XLR designated as channel 1. Pin 3 of the female XLR will go to pin 3 of the male XLR designated as channel 2. Refer to Figure 2 for details. Us- ing two adapter cables the Model 46 can be directly interconnected with four Clear- Com intercom circuits. However, power for the connected devices must be provided by external power sources. The Model 46’s ability to supply intercom power will not be utilized.
Figure 2. Adapter cable wiring diagram
Note: It’s critical that the correct con- figuration settings be made when using the Model 46’s interfaces to support four independent intercom circuits. Specifically, the 2-wire power source configuration DIP switches must be set for external. In addi- tion the auto terminate disable DIP switch must be placed in its on (up) position.
Refer to the Configuration and Advanced Configuration sections of this user guide for details.
Remote Control Inputs
The Model 46 allows connection of three externally provided DC signals. These signals can provide remote control opera- tion of three functions: auto nulling for interface 1, auto nulling for interface 2, and a special “mic kill” function. Remote con- trol of the auto nulling functions provides a resource identical to that of the front-panel pushbutton switches. The exact manner in which the buttons and the remote control inputs operate depends on the setting of auto null button mode configuration DIP switch. The “mic kill” function is unique, only being available using the remote control input. It causes a 500 millisecond “burst” of 24 kHz signal to be sent se- quentially to both of the 2-wire partly-line interface channels associated with each of the Model 46’s two interfaces. To clarify, a “mic kill” signal is sent to a total of four intercom channels whenever the func- tion is activated. Independent control of sending “mic kill” signals to interface 1 or interface 2 is not supported. User intercom devices compatible with this 24 kHz “mic kill” signal include RTS TW-series belt- packs such as the BP325.
The opto-coupled remote control inputs are designed for direct connection with
3.3and 5 volt DC logic signals. An internal
475 ohm resistor, in series with each opto- coupler’s photodiode, acts to limit the current flow. Signals of up to 32 volts DC can be safely connected as long as the current is limited to 20 milliamperes maxi- mum. If necessary, an external resistor can serve to limit the current. For example,
