KB905: BDL162 - Increase Detection Section Threshold Sensitivity

This article was last updated on May 16, 2012, 3:12 p.m. | Print Article | Leave Feedback



How do I Increase BDL162 Detection Section Threshold Sensitivity

The BDL162 has Option Switch settings to control detection sensitivity. The factory setting is OpSw19=t for a threshold sense for DCC occupancy of approximately 22 Kohms minimum. Changing OpSw19=c will set the threshold to 10 Kohm minimum. See the BDL162 instruction manual for details on setting the Option Switches. These settings will accommodate most layouts, though there may be circumstances when a higher threshold is desired, for example, in a high moisture environment or with G scale operations outside.

To raise the threshold even further resistors can be added into the wiring between each detection zone and the zone common on the blue connector. The following resistance values can be added to increase the detection threshold (with OpSw19=t):

1 Kohm resistor will increase the threshold by about 2 times (to about 10Kohms)
100 Ohm resistor will increase the threshold by about 10 times (to about 2.2Kohms).

The following example shows resistors selectively added into detection sections 1 and 2. Resistors can also be added between the other detection sections and the zone common if required by conditions in those sections.

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