Direct Current [DC] operation on NCE
decoders.
DC capability is one of the features that a manufacturer of a NMRA
compatible decoder can incorporate into a decoder, this feature was
originally made available to facilate the introduction of DCC to the
modeller.
The NCE Ver. 3.5 decoder’s feature improved DC compability over previous
versions.
It is important that the modeller intending to use this feature understand
how it will operate and the limitations.
The MRRC warranty test station consists of a OZ 2000
DC power pack.
It incorporates additional filtering provided by two
2000 uf 25V capacitors. The manufacturer claims a pure DC output but
it dose require this additional smoothing for reliable operation.
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The first consideration in selection a suitable throttle for use with a DCC
decoder to run using DC - the power supply to the track must provide a
smooth DC for reliable operation and any form of ripple can be interpreted
by the decoder as a form of signal that may prevent the changeover to DC
operation and sensitivity will vary from decoder to decoder in any layout.
Note: By default the auto switching to DC operation is turned off in all NCE
decoders. The DC on feature can be a source or runaways when operating on a
DCC equipped layout. The MRRC recommends that this feature be turned on when
required to operate on a DC layout.
A simple filter can be added to any DC throttle by fitting additional
filtering as per the attached photo. Throttles that use a Pulse Width
Modulated output for DC operation can be considered unsuitable, but before
any modifications to your throttle are undertaken you should consult the
manufacturer for their recommendations.
Operation of the decoder on a DC layout.
The NCE decoder has to be provided with about 6 + volts for a few seconds
initially, this provides the decoder with the necessary power to change from
DCC to DC operation.
The throttle should now be closed, direction selected and opened as normal.
The engine will begin to move at about 25% throttle, you still have to
operate the decoder, change direction as per normal.
If the power is reduced to zero for a period the decoder will reset itself
to DCC mode, if so the decoder start-up will have to be repeated.
Features.
One of the nice things that can be done with a decoder is to turn on the
headlight with a DCC system, and when powered up in DC the light will
operate, additionally if a FX feature is assign to that output it will be
present during DC operation. [Thanks to the boys from the NSW Epping Model
RR Club]
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