DC-DCC
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originally made available to facilitate the introduction of DCC to the
modeller.
The NCE Ver. 3.5 decoder’s feature improved DC capability over previous
versions.
It is important that the modeller intending to use this feature
understand how it will operate and the limitations.
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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]