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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Sat, 23 Aug 2003 21:41:12 GMT
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Viewed:
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2006 times
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<SNIP>
>
> During the DCC conversion described by Tom Cook, there is some kind of
> semiconductor that gets removed from the train motor. I wonder if this
> component is somehow responsible for preventing excessive current in the motor
> windings? Judging from the ceramic case and the size of the electrical
> contacts, this component is rated to handle some power. Does anyone know what
> this component is or what its purpose is in the train motor? Is there a way to
> leave it in the circuit of a DCC-converted engine?
Hi Chris and all others,
If you open a Lego train motor, you'll find there 3 electrical components in it.
First, and largest part, is the motor itself, second is a 'black cilindrical'
piece witch is placed in parallel with the motor contacts. This part is a kind
of verry fast acting bi-polar zener diode. The right name escapes me, but its
use is to reduce electrical noise and spikes. I recommend you all to keep this
electronic part in place. It can prevent the decoder power stage to blow up
caused by spikes, witch can be verry high in voltage.I did blow up the
microcontrollers I/O ports from a decoder witch controls the power transistors
for the motor past year at the Lego World Event in Zwolle.
Now i replaced all those pieces again ! A new programmed PIC microcontroller
cost me 30.65 Euro. Pritty expensive!
The thirt part you'll find is a kind of cilindrical thin slice with shiny
contacts. This is a kind of electronic fuse (i guess it's a poly fuse). The use
of this part is to prevent the motor for burning out. If the current through the
motor (and also through the polyfuse - its placed in series with the motor) gets
too high, then the poly fuse gets active and 'cut ' the power to the motor.
When cooling down, the poly fuse recovers and the motor can run again. Thats
what some people noticed allreddy. When overloaded (example: Santa Fe with bad
wheelsets) the train first slows down, and stops after a while. When they take
the motor from the track (cutting also the power to the motor) to cool down, the
motor can run again after a while. Thats also a kind of safety for the motor. I
havent seen replacement motors at hobby centers yet. Replacement with a original
Lego train motor is expensive. It's up to you what you want to do.
For pictures of my modifications, you can take a view at:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=16529
You can also go to my home page at :
http://www.geocities.com/ludo_soete/ and select : DCC in the Index column.
I placed my decoder outside the motor block, first it doesn't fit and second, i
use functions for the front and rear light of the locomotive. On one locomotive
use i an other function output to connect 12V Lego light bricks (2x2) into my
passenger cars.
I hope this explanation helps you all.
<SNIP>
> - Chris.
Regards,
Ludo
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Message is in Reply To:
 | | Re: DCC slowing?
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| (...) During the DCC conversion described by Tom Cook, there is some kind of semiconductor that gets removed from the train motor. I wonder if this component is somehow responsible for preventing excessive current in the motor windings? Judging from (...) (21 years ago, 23-Aug-03, to lugnet.trains)
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