BERKSHIRE PRODUCTS PC Watchdog, Руководство по оборудованию, Страница: 12 / 19

4.4 Auxiliary Relay
There is a second set of relay contacts that are on the 1/8" (3.5mm) stereo jack on the bracket above the
LEDs. The two relay contacts are on the inner two contacts of the jack (Tip & Ring). The sleeve of the
jack is grounded through its connection to the bracket. This relay can be controlled by software. These
dry contacts can switch a maximum of 24 volts and 250 mA. Do not exceed these ratings.
A good source for the plug to use with this jack is the Radio Shack PN: 274-869. Another option is to
get a 1/8” (3.55mm) extension cable from Walmart, Best Buy, etc and cut off one end. Strip back the
insulation and use the two inner conductors.
4.5 External Digital Input (Rev-C Boards)
This input is on the lower stereo jack at the bottom of the bracket on Rev-C boards. The input accepts
levels from 0.0 to 5.0V and it has a l.0K pull up resistor to keep the input high when it is unconnected.
The pull up also allows the user to connect a dry contact switch to the jack to pull the input low. The
Ring (Right channel) terminal of the jack is connected to the input and the sleeve of the jack is ground.
The Tip (Left Channel) contact of the jack is not used. The DLL has a function that allows this input to
be used as digital input and and an external “tickle”.
The figure below shows the schematic connection on the jack:
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