Re: reducing power on yard tracks

David Starr wrote:

Charles Davis wrote:
tex shalter wrote:
Thanks Geezer and Bill.

< Why do you want to reduce power on some tracks?

Maybe I'm going about it wrong.- DC system. Locos speed up ( if throttle
unchanged) when entering switching yard with 5 to 6 foot track blocks.

That symptom, sounds like your 'track feeders' are not as large as they
should be.
I.E. you are getting MORE voltage drop on the longer feeders. The Yard
tracks are close = shorter feeders.


If there is a better way than adding resistors- I'm all ears

Yes, if you are looking for a 'drop in voltage', the easiest way to not
have problems caused by differing 'trains /locos' would be to use
'pairs' of rectifier diodes (1/2 amp for N, 1 amp for HO, 5 amps for O).

The Diodes, IN PARALLEL, with one diode in each direction, will pass the
majority of the applied power, only adding approximately 1/2 to 3/4 volt
drop to the circuit. Need to slow things down more, add more 'diode
pairs' (these in series with the initial ones).

Chuck D.

However, be aware, this answers your question as stated. You may not
have asked the proper (whole) question.

CD

I am not sure even four diodes (two forward and two backward) will
reduce the speed of an HO locomotive enough to be worth it. I put
constant lighting into some of my locomotives and they didn't slow down
enough to notice. (Constant lighting robs 1.4 volts, two diode drops
from the motor)
It may require something like 4 or 5 volts reduction before the
locomotive slows up much.


You've highlighted the real problem with diode voltage dropping!
Train A might require 12 volts to maintain a scale speed whereas train B
might require 4 volts to maintain scale speed.
If you drop 1.4 volts Train A will get 10.6 volts (88%) and will barely
slow whereas train B will get 2.6 volts (65%) and may well stop
completely.

One can even that sort of problem out a bit by installing series diodes
in locos that run too fast, or by remotoring.
It's also possible to build a seperate controller feed from the track
supply to deliver a percentage of the track supply, but that is most
likely getting too complex for most people.

Regards,
Greg.P.
.

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