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Motor Capacitors

Many Locomotive made by a international manufacture are required to have "motor capacitors" installed in DC locomotives to meet certain government agency requirements.  This includes locomotive that are "DCC ready" which are DC locomotive that are ready to accept a plug in DCC decoder.

These capacitors are NOT needed when there is a DCC decoder is installed.

Advance DCC decoders with an ADVANCED motor control feature called BEMF or Back Electro Motive Force WILL HAVE PROBLEMS.  Most sound decoders have BEMF and call it that.   But there are some decoder manfuactures which have chosen to market BEMF under different name of the company's choosing.  HyperDrive2 (Soundtraxx), Locomotion (Digitrax) and Regulated Throttle Control or RTC (QSI)

The problem is when BEMF is turned on, it is very hard to get the best possible slow motor control performance out of the decoder when motor capacitors are present.  At worse the BEMF fails to function and poor locomotive operation results that is worse then with BEMF turned OFF!!.

Bachmann is one of those manufactures that installs these capacitors and has information, publicly available but buried under different topic headings, saying you should remove the capacitors when you install a DCC decoder.  This will not violate Bachmann's warrantee.

To learn more go here: Motor Capacitors
To go directly to Bachmann info, go here: Bachmann Engines Capacitors
To know more about what is a capacitor is, go here: Capacitance