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My dear Forum friends.....I want to put a smoke unit in my Great Northern 0 gauge I think I want an actual smoke unit....not the stock tube type that came in it.....I want “Lots” more smoke than the original one....I’ve taken that one out.....I’ve put lights in it with a switch that can turn them off one on.....I want to do the same with the smoke unit.....looking to do this in the most inexpensive way......I’m open for your suggestions.....EZ Money 

Original Post

I've used the MTH HO fan driven smoke unit in a number of cabooses.  It puts out a nice volume of smoke, certainly can be more than a caboose that's not on fire should be putting out, and it's small so it's easy to fit in.  You do have to arrange to power it, the heater takes around 5-6 volts and the fan motor runs on 2-3 volts DC.

Here's the HO smoke unit on the bottom and also the small O-gauge smoke unit on the top, both MTH products.

@EZ Money posted:


looking to do this in the most inexpensive way...

What he said.  A fan-driven smoke unit is the key.  There have been several OGR threads on retro-fitting smoke into cabooses but inexpensive can be an issue.  In this OGR thread from 2016, I identified two MTH smoke units but were $45 and $50 (plus shipping).  There are some other assembly tidbits of info in that thread that might be of interest to you.

My video link in that thread seems to generate an error so let's see if it embeds here:


Does the ho unit as a whole, remain cooler in general by any chance?  Or is it a just as hot tot?

Ive seen it done in battery toys with some finer wire to stay cool enough for cheap plastic. (used water and vegetable oil as fluid.... and smoked after storage, ran dry ok, etc. )

If you ever do need a small remote mount, silicone pill/coin cases I tried can take the heat of an element without issue and provide a fluid well. It's slip fit top to base seal is resistant to leaks if filled high. (might weep a half-drop or so; I've seen weepier new) Pw disc elements fit perfectly. About the size of $1 in quarters.

I've built many custom fan-driven smoke units...not so much because of cost but because a stock smoke unit would not fit.  When you think about it, a smoke unit has very inexpensive components.  A $1 DC motor, a fan/impeller blade (which can be hand-crafted from thin sheet metal), a smoke heater resistor (I'd buy them for $1 from MTH), and a smoke chamber which I'd typically fabricate for the job-at-hand using thin brass sheet metal or brass tubing. 

The key point is the electronics is the same whether driving a $50 MTH fan-driven unit or my <$5 (in parts) custom fan-driven smoke unit.  If I were to summarize some take-aways, I'd say you don't need as much airflow as you'd think to stream smoke.  And that the more interesting smoke effects are intermittent or burst-like such as simulating train puffing or startup exhaust from internal combustion engines or firing weapons.  It's happenstance that the pulsing electronics that can start/stop inexpensive fan-based DC can motors works out for these applications.

Stan, you method of fabricated smoke unit is more up my ally....could I just use a unit that is for liquid fluid and just mount it in my caboose and run my brass tubing down from the roof into the top cone of the smoke unit....would I get a good steady smoke flow up the tubing that will come thu the roof top smoke stack.....I’m not sure how hot this unit gets but I’ll have it in the middle of my caboose...I will not be using a fan with this unit.

Last edited by EZ Money

Well, that's a YMMV situation.  Here's how I think of the problem without any nerdy physics or math.

Heat rises.  So you're depending on the heat from the chamber to rise up carrying with it whatever smoke fluid you vaporized.  I compare it to the classic rotating lighthouse and the like where rising heat from a resistor generates just enough upward air flow to spin a lens or whatever on a needle-point bearing.  So I suppose cranking up the heater power increases the smoke output in part because you vaporize more smoke fluid...but also because the hotter chamber will create that much more rising-heat airflow.

But the extra heat will also conduct thru the chamber into the caboose where the melting plastic phenomenon rears its ugly head.  Hence, the addition of a fan.  Just repeating myself but tiny DC motors are less than $1...


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