# Concept for a Home-made Smoke Generator



## rhyman (Apr 19, 2009)

Here is something I'm currently working on. I invite all comments and suggestions - especially if anyone has already tried some of this.

Most model smoke generators make the locomotives look more like children’s tinplate toys rather than real fire-breathing iron horses. I have always thought that there must be a better, more realistic, method for generating the appearance of a smoking locomotive. I have been experimenting with many of the commercially available smoke generators, including the Bachmann, Seuthe, and Micro-mark models to see which type would work best for me. I was not totally happy with the results from any of them. 





I decided to try and create my own system from readily available components. The design goals were fairly straightforward:
[*] Realistic – the smoke should “puff” from the stack in synchronization with the chuff outputs from the sound system.
[*] Long Duration – the system should operate for at least thirty minutes between refills.
[*] Low Power – the system should not consume more than 500mA at 14.8VDC.
[*] Inexpensive. The entire smoke system should cost less than $50 to build.
[*] Low Operating Cost – the smoke fluid should be inexpensive and readily available.
[*] Safe – all materials used, including the smoke fluid, must be non-toxic.
[/list] 





After seeing a “fog generator” machine being set-up for an upcoming Halloween party, I decided to design a smaller version of it to fit inside of a locomotive boiler. “Fog juice” is readily available at around $25 per gallon. 





For the fog nozzle and heating element, I am using the print head removed from an empty ink cartridge out of my HP inkjet printer. For the air pump and solenoid valve, I cannibalized parts from a Oregon Scientific wrist mounted blood pressure monitor that operates on two AA batteries. For system power, I am using a 14.8 Volt 2200mAh rechargeable Li-Ion battery pack. 





The system will basically work something like this: The air pump pressurizes an accumulator tank made from a short length of ½” diameter copper tubing. The pump consumes less than 380mA at 3VDC. The pump shuts off when the accumulator pressure reaches 7 PSI. Unrestricted air flow is > 1.2 liters per minute. All pneumatic connections are 1/8” plastic tubing. 





A solenoid valve releases air from the accumulator tank into the stack. The solenoid draws less than 75mA at 3VDC. The solenoid is activated by a ground signal provided by the opening and closing of the chuff cam. At slow speed, each chuff causes a single puff of air to be exhausted up the stack. After reaching a running speed of TBD, the valve will stay open and the pump sends a steady jet of air up the stack. When the locomotive slows down below the TBD speed, the individual puffs will resume. I’m still playing with a comparator logic circuit to adjust the transition from the individual puffs to the steady stream and a timer circuit to adjust the duration of the individual puffs. 





The print head normally operates on 24 VDC. I haven’t made current measurements yet. There are approximately 600 individual nozzles on the head and total current draw will depend on the applied voltage and how many nozzles I choose to fire at the same time. I have verified that the print head will produce fog by filling an empty ink cartridge with “fog juice” and putting it back into my printer. I have had mixed results thus far. I’m having difficulty getting the residual ink out of the empty cartridge although I have managed to get the printer to “smoke” to a small degree. By the way, fog juice mixed with black ink does not produce black smoke … only a mess! This part of the experiment is going to take a lot more trial and error to get to a print head that will send clean fog up the stack. I also still need to design some type of holding tank for the fog juice and a method for re-filling it. 





The components are spread out on my workbench and most power and logic circuits are still in the breadboard stage. I’m thinking about adding a heat sink to the accumulator and a piezo-electric thermal chiller element to cool the air before it is exhausted up the stack. This should greatly enhance the condensation of the fog particles that create the smoke effect. 





I’m only part way into this experiment, so feel free to jump in with suggestions and comments. There is no sense in “re-inventing the wheel” if some of you have already “been there - done that.”


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## Greg Elmassian (Jan 3, 2008)

First, I noticed that you did not experiment with any of the fan driven smoke units, nor the ones that "puff". 

I would suggest buying the Aristo-Craft "prime mover" unit (with the fan), one of the MTH units (they are all similar, but different sizes of reservoirs), the Massoth (which has the ability to puff). 

I'm not including the TAS unit, because it's really no longer available, and the USAT ones are not as good as the Aristo, and are similar (fan driven but no puffing). 


You might want to look at my page: *http://www.elmassian.com...>*

I think all of your goals are good (the bullets)

Your idea sounds great.

I do need to warn you that Aristo has a patent on a smoke unit that uses a pump to squirt fluid on a heated element. (They have not produced the product yet, but the part number has shown up a couple of times in their documents)


Be SURE that you steer clear of their patent. 


Good luck, I would suggest you look into protecting your idea right away. 


Regards, Greg *
*


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## david bunn (Jan 4, 2008)

Good luck it sounds very interesting. 
Regards 
David


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## Jerry Barnes (Jan 2, 2008)

Verrrrrry interestink!


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## FH&PB (Jan 2, 2008)

But if you're just building it for yourself, you shouldn't have to worry about patent lawyers coming after you. 

I like your algorithm for puffs versus a continual stream. Find your local live steamers and watch their locos run for a while and you should be able to get the speeds you need pretty quickly.


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## virgal (Sep 25, 2009)

Have you seen this one?

http://www.youtube.com/watch?v=eQ7mNYpSDFw


check it out . it may be of some help

alan


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## jimtyp (Jan 2, 2008)

My input: 
- Funny, as I was thinking the same thing about a fog unit after going to a concert recently, but I don't have the expertise to "shrink" it down 
- How big is the unit? The same size as say the TAS, or MTH or Massoth? I ask because size might limit how many locos it can fit into. 
- I have a TAS unit and love the puff and chuff in sync, but if that is too much for a first run, I'd still love to get more smoke, cheaper.


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## FH&PB (Jan 2, 2008)

http://www.youtube.com/watch?v=eQ7mNYpSDFw



That's pretty good. While it's running, the stack exhaust coordinated with the sound system is really effective.

There were two problems with it: the steam from the cylinder cocks would not be drifting out lazily. That's under very high pressure, straight out of the cylinders, so if you're going to have drain cocks, the little jets of steam should really shoot out from them.

Likewise, when it's standing still, the smoke just kind of drifts out. On an actual steam loco, the fire would go out if there weren't some draft, which is provided by a steam blower. This vents a little steam out of the boiler, up the stack, to keep a little partial vacuum in the smokebox to draw air through the fire. So, standing still, there should be a small, steady stream of steam coming out of the stack.


Yep, it gets complicated. But turning on a blower while stopped shouldn't be too hard, if you can work all that other stuff.


Nice project!


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## Torby (Jan 2, 2008)

If you want black smoke, I've found that some IC chips contain lots of it


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## lownote (Jan 3, 2008)

Any updates on this idea? It seems workable--there's a commercial outfit in Germany that makes a 4 inch smoke generator using "fog juice"--out of the case it would seem like it could work


But they want $1450 for it!

When theatrical productions of hollywood want smoke, they don't vaporize lamp oil. This seems like a great way to go.


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