Subject:
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Re: DCC slowing?
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Newsgroups:
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lugnet.trains
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Date:
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Mon, 25 Aug 2003 09:09:04 GMT
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Viewed:
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1600 times
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I wonder if this is a caused by low track voltage?
The DCC decoder does not put a steady voltage to the motor but rather pulses the
motor with the duration of the pulses increasing for increasing speed.
Although the motors are no doubt vulnerable to overloading I very much doubt
that they are very critical concerning voltage. If it takes 9 volts at 100%
pulse width to haul your heavy train it might require only about 75% pulse width
at 12 volts. This would be about the same amount of energy going into the motor
and hence the same amount of heat inducing power.
If you are starting with 9 volts to your DCC controller there will be something
considerably less on the motor terminals and although the motors are rated at a
nomimal 9 volts they can undoubtedly tolerate a lot more when the supply is in
the form of pulses.
The decoder being an assembly of semi-conductor junctions will heat up less on
the 75% pulse than the 100% pulses. Someone might like to correct me if I am
wrong. My reasoning is that more volts mean less amps to do the same work and as
the junctions in the decoder are constant voltage drop that means less amps will
produce less heat.
INMO using less than optimum voltage puts unnecessary heat strain on the
decoders and it may be the decoders that are shutting down.
On my system I use a regular DCC controller and a transformer in a combination
that puts something like 12 volts on the track. Obviously if I were to select
100% pulse width I would overload the motors (so I don't). I have not noticed
any slowing down but I have never run for extended periods of time and neither
do I have any really heavy trains.
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Message is in Reply To:
 | | DCC slowing?
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| I have a question abuot DCC. I was first exposed to DCC at our last LUG meeting where some of the motors had been modified. They were running 2 motors on the track on different channels. Then we placed the two motors on the same channel and placed (...) (21 years ago, 13-Aug-03, to lugnet.trains)
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