DCC & Smoke Generator

Discussion in 'DCC & Electronics' started by Freelancer, Jul 29, 2004.

  1. Freelancer

    Freelancer Member

    I am trying to install a decoder in one of my steam engines. Upon disassembling the engine I came to the smoke generator and found that it has a wire connecting to both sides of the frame. I don't know exactly how these work, but I am assuming (you know what assuming does) that it works like a light bulb. As power moves through the wire, it heats up and causes the smoke liquid to evaporate, or whatever it does. Did I come close or did I completely slaughter that. Anyway, won't this wire cause my decoder to short? If it will, then how do I wire this beast?

    Thanks, Freelancer

    Attached Files:

  2. 60103

    60103 Pooh Bah

    I'll go for your explanation of the smoke unit.
    If you leave it wired as it is, it will probably really start cooking from the extra voltage the DCC uses. I expect you should rewire it to operate from one of the spare functions on the chip.
  3. Fred_M

    Fred_M Guest

    I would for sure hook it to a function on your decoder but for another reason. If you leave it alone it will smoke all the time. The power on the track in DCC is always on (just put a DC loco on and note the headlight is always on) so your smoker will get around 12vac at all times. Just use a good decoder that can handle the amp draw of the smoker through the decoder. I would call and order one from a DCC speciality shop like Tony's Trains. http://www.dcctrains.com/ Fred
  4. Gary Pfeil

    Gary Pfeil Active Member

    I don't know of a decoder which can handle the amps of a smoke generator. I've seen the issue addressed at the Digitrax group, they use a relay activated by one of the decoders functions. By all means call Tony's and ask.
  5. Freelancer

    Freelancer Member

    Thanks for the input guys. I just posted my question in the Digitrax group and I will see what they have to say. If they can't help me then I will see what Tony's can do. You say call them? Do they have a tech support that could help me? Or are their sales reps just really good?!

    Thanks, Freelancer
  6. Gary Pfeil

    Gary Pfeil Active Member

    Tony can help you, Ken probably can. None of the others. 800-978-3472
  7. Freelancer

    Freelancer Member

    Great, thanks for the phone#! I have a feeling that I will most likely be using it. Someone at the Digitrax group just responded to me, and just like you said he is suggesting a relay. I will give his ideas a shot and then give Tony a call if this doesn't work. I will keep you updated.

    Thanks for your help, Freelancer
  8. Freelancer, what were you able to find out, I also to add a decoder to a steam engine that smokes.
  9. Freelancer

    Freelancer Member

    Well....hmmm....I found out quite a bit. The only problem is, is that I have been convinced to not proceed with the installation of the smoke unit to DCC. :cry: I had a gentleman from the Digitrax user group help me with what I needed to know and do to get it installed. It definitely takes a lot more work than I thought. You can go to his web site to find the schematics of the installation. It is at the bottom of the page.

    http://www.tcc.on.ca/~bobyoung/decoder installs.htm

    The following is and explanation from the gentleman on how it is all supposed to work. I suggest that you look at the schematics on his web page before reading this, it will make more sense.

    "You need to use a relay to flow track power through the smoke
    generator, controlling it via a function output. To the best of my knowledge a
    smoke unit will draw far more current than can be sourced by any decoder,
    regardless of scale. A given function circuit (white, yellow, green or
    violet) of a decoder (HO scale in particular) can only sustain current
    from 100ma to 150ma. A smoke unit will demand current of 500ma to 1500ma. The end result is obvious, the decoder function circuit is destroyed.

    The purpose of the relay is to act as a high current switch that can be
    controlled by the decoder. The decoder function current can safely
    sustain the current required to operate the relay coil/armature, the relay
    contacts switch the smoke unit 'On/Off'.

    The relay will be activated by the decoder 'function', similar to a light.
    The relay requires a single 'normally open' contact. You should be looking
    for a 'reed relay' or a 'PCB relay'. Therefore you should be looking for a
    relay that has a coil/armature rating of 5vdc to 10vdc at 20ma to 50ma.
    You will also require a series current limiting resistor, the size of which will
    depend upon the relay coil/armature rating. Assuming a 50ma current for the relay coil/armature you would require a 120ohm, 1/8w resistor series resistor.

    The cab switch is an option that is not really necessary. The cab switch
    allows the user to run the locomotive without fear of the smoke generator being turned 'On' inadvertently.

    The bridge rectifier is used to rectify the DCC track voltage into uni-polar
    DC. The voltage regulator was used for this specific installation as it was
    'S' scale. The user was using 'HO' scale DCC voltage which turns out to be
    about 14vdc. The regulator ensures a constant 12vdc source voltage for the
    'smoke generator'.​

    I figured that I would hold off on the installation of this until I was more comfortable with DCC. Also, I have been told that the after affects of the smoke 'oil' is not something that anyone wants to deal with. I haven't personally had problems with the oils, but apparently it is a big issue. Also the fact that it doesn't look realistic was brought up, but I could care less about that because I think it plain out just looks cool. I hope this has helped, and am sorry if it as deturred you from wanting to wire your smoke unit for DCC. If you do get it wired please let me know, I am still quite interested in doing it and if by some chance I do continue on with it, I will let you know of my progress.

    Thanks, Freelancer
  10. Russ Bellinis

    Russ Bellinis Active Member

    The biggest problem with a smoke unit and dcc in small gauges like n or ho, is that the residue left from the smoke dirties the track considerably. The most essential thing we have found in the modular club I belong to is that the track must be extremely clean for the locomotives to pick up signals. Our club uses a cordless dcc system. A tether system may be different, but we found when we ran straight dc that we had problems when we set up at a show next to the Lionel or LGB guys, and had to deal with the residue from their smoke units on our tracks.
  11. Fred_M

    Fred_M Guest

    Thanks for the skinny on this subject guys. Fred

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