KB674: Zero Stretching-Operating a Non-DCC Equipped Locomotive with Digitrax

This article was last updated on July 31, 2011, 9:32 a.m. | Print Article | Leave Feedback

Digitrax Command Stations can operate one locomotive on your layout that does not have a decoder installed. This loco is called an "analog," "conventional," or "non-DCC equipped" locomotive.

To operate an analog locomotive with Digitrax you will use address 00 to send commands to the locomotive.  The magic that makes this happen is called zero stretching. With Zero Stretching, an analog locomotive going forward receives an unusually long positive voltage, followed by a very short negative voltage. The much larger positive voltage ensures the locomotive moves forward. The brief negative pulse causes a low buzzing that will vary with the speed of the locomotive. This method of control causes locomotive motors to run hotter than normal.  For this reason care should be taken when using this method of control.  The motor is being switched on and off even when the loco is set at 0 speed and is standing still.

It is highly recommended that you remove any analog locomotives being run on DCC from the track when they are not actively running.  DO NOT LEAVE AN ANALOG LOCO SITTING ON A DCC TRACK AT 0 SPEED!!!  This can cause heat damage to your locomotive.

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