DCC and Smoke
#1
OK, unlike several other topics discussed here, I don't necessarily want to control a smoke generator from the decoder, I just want to know if smoke generators can be made DCC-compatible... that is, run directly off track power.

I know that the smoke generator is seen by most DCC systems as a dead short because of its' low resistance - but I'm wondering if I put a diode rectifier and resistor in series with it, will it be enough to make it work?

I'm doing an install for a client, and the decoder he's provided me with doesn't seem to have any accessory function outputs (nevermind providing any useful specs for the outputs at all... Curse )... but he'd really like the smoke to work. So I figure if there's a way to run it off track power, that'll make him happier than me having to say it ain't a gonna work atall Misngth
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#2
Would it be acceptable to wire it in directly to the motor? Same operation as now, only when running.
David
Moderato ma non troppo
Perth & Exeter Railway Company
Esquesing & Chinguacousy Radial Railway
In model railroading, there are between six and two hundred ways of performing a given task.
Most modellers can get two of them to work.
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#3
True, but I've read if I do that, it'll only make smoke at full throttle.... although I guess that'd be how it would work on DC too, wouldn't it?

Failing any other suggestions, I'll try that. Thanks! Thumbsup
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#4
If you run the smoke unit from the track, which in DCC the power is always on, then the chances are that unless the user is really careful, when the smoke unit runs dry it will overheat and melt the loco body.
If the decoder is of such a low spec. that it doesn't have any accessory outputs then attaching the smoke unit to the motor contacts will almost certainly overload the decoder and destroy it.
What's needed is a decoder that can cope with the extra power consumption that a smoke unit draws, such as a Digitrax DN121 or similar. The correct smoke unit is vital too. If the loco has a plastic body then I would suggest using a Seuthe #22 which is specifically designed for the purpose. Power consumption of the Seuthe #22 is 140mA.
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#5
You could use one of the functions to control a relay. The relay then could operate fhe smoke unit from track power.
Watch the restance on the relay coil, it could exceed the max on the functiuon output of the decoder.
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#6
woodone Wrote:You could use one of the functions to control a relay. The relay then could operate fhe smoke unit from track power.
Watch the restance on the relay coil, it could exceed the max on the functiuon output of the decoder.

... I could, except:
Squidbait Wrote:I'm doing an install for a client, and the decoder he's provided me with doesn't seem to have any accessory function outputs
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#7
Are all of the lighting functions being used? If not use the rear light function and remap .
If the rear light function is being used, I have no more ideas.
Upgrade the decoder to a four function decoder or add a TCS 2function light decoder.
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#8
OK, no dice on putting it in series with the motor - the system sees it as a dead short. So no smoke for buddy.

The sound decoder (MRC 1639) is already worth more than the loco he wants it installed in, I don't think he's going to pop for a higher-end decoder just for smoke.

So it's wired for sound, runs fine, sounds much better with a 1" speaker in the tender than the 1/2" POS that came with the decoder... Thumbsup
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#9
Wire it directly to the track and use a magnetic reed switch to turn it on and off.

Harold
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#10
As the MRC 1639 is an 8 pin decoder it should have spare connections for fitting to a smoke generator. Try contacting MRc customer support for advice.
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#11
hminky Wrote:Wire it directly to the track and use a magnetic reed switch to turn it on and off.

Harold

No can do. The resistance of the smoke unit is so low (it's basically just a thin wire wrapped around a rod) that the DCC system sees it as a short circuit.
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#12
poliss Wrote:As the MRC 1639 is an 8 pin decoder it should have spare connections for fitting to a smoke generator. Try contacting MRc customer support for advice.

Already asked on the MRC Yahoo! group, where MRC Tech staff usually respond... except in my case. Nope
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