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 Robotics / RCX / 2087
2086  |  2088
Subject: 
Re: DCC for the RCX
Newsgroups: 
lugnet.robotics.rcx, lugnet.trains
Date: 
Wed, 28 May 2003 21:20:25 GMT
Viewed: 
4297 times
  
"David Koudys" <dkoudys@redeemer.on.ca> wrote:

When I originally did the research and found the cost to be a little high, • I
noticed that on (I think Todd's page) that there were capacitors and • resistors
installed in teh LEGO train motor--the resistors to make sure that only 9v • goes
to the power connector on the top of the motor, since most DCC controllers • run
at 12 volts.  The capacitors were installed to decrease the 'buzzing' of • the
motor at low speeds.

Now since hte RCX runs at 9v anyway, the resistor, as far as I understand, • isn't
needed--the power output will already be at 9v.

What about the capacitors in the motor?  will they still be needed to • reduce the
motor cycling 'buzzing' at low speeds?

David,

When I installed my first decoders (Digitrax DN121), I omitted
the capacitors, figuring if the buzzing was annoying, I could always
add them later.  As it turns out, there is a little buzzing at low
speeds, but it is not annoying to me (YMMV).  In fact, for my
diesels, it sounds like a low grumbling which reminds me of the low
"thrumming" you get as the prototype leaves the yard.  I just
installed a DZ143, and it buzzes at about half the volume of the
DN121s.

If you are referring to Tom's L-Gauge page, the resistor is
used for the headlight to lower the ~12V DCC voltage to 9V
for use with a standard Lego lamp brick.  I didn't need to
use this resistor since the RCX is already putting out about
9V.

I did however, add a diode in parallel with the lamp output
in case I decide to run an inductive load such as a
relay or motor on the lamp output.

One thing to note, since the DCC decoder drops the voltage
somewhat, the actual train motor is only seeing about 7V.  This
means the locomotives aren't as zippy as with the standard
train regulator.  Nonetheless, if you're operating a few trains with
5-6 cars each, it shouldn't be a problem.  For a large club layout,
an external booster is probably advisable, though.

Cheers,

Mark



Message has 2 Replies:
  Re: DCC for the RCX
 
In lugnet.robotics.rcx, Mark Riley wrote: <snip> (...) Mucho appreciated Mark. The Diode--any diode will do? and just solder it across the connector output? Take care, Dave (21 years ago, 28-May-03, to lugnet.robotics.rcx, lugnet.trains)
  Re: DCC for the RCX
 
(...) I don't install them either, and I have done something like 30 motors so far. (...) True, but ONLY if you are just going to use the RCX as a output. You can dial the voltage that DB100's (and most other Digitrax) boosters put out to a exact (...) (21 years ago, 29-May-03, to lugnet.robotics.rcx, lugnet.trains)

Message is in Reply To:
  Re: DCC for the RCX
 
(...) Oh My Goodness! This is what I've been waiting for--when I priced out DCC controllers, they were 200+ CDN... If I can get one of my many RCX's to do it, well that's entirely another matter. When I originally did the research and found the cost (...) (21 years ago, 28-May-03, to lugnet.robotics.rcx, lugnet.trains)

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