Smoke!

[tramcar trev]

So everyone has tried making smoke?
Did you hear I'm gathering bits to build a battery powered steam tram? So, it will have a Li Po battery inside its little fake boiler and I'm going to try and make smoke appear from the funnel.... To this end I have to design and make my own smoke generator as the commercial ones are expensive and don't work that well. So I propose to make up a short cylinder from copper tube and a solder on some flat ends with a small length of 10mm brass tube ( that pokes into the funnel)out of the side. Inside will be a small length of Ni-Chrome wrapped around a piece of fibreglass rope the ends of which will sit in proprietary smoke fluid dropped in through the brass tube........ On one end of the cylinder will be a 25mm fan that draws.......08amps (80mA?). To get the "chuffing effect" I think if the fan could be pulsed on and off while the element stays on a realistic effect could be got. I'm thinking a simple led flasher using a 555 would work to switch the fan on and off, the circuit in the picture is using 9v I will have 11.1 and 6.8ah from the Li Po battery do you think the 555 could handle the 11.1V.? the rate of "flash" is controlled by the resistor values..... I did think a cam on an axle switching a micro switch on and off would work to but then space is off the essence . Thoughts? Opinions? Been there tried that?

 

[Rhinochugger]

Get the wiring to the LiPo wrong and that should do the trick

 

[muns]

You could always drop a couple of diodes to reduce the voltage to the 555 a bit!

 

[Madman]

I've had success with USA Trains fan driven smoke units. However you may not have enough space for one of them. I give you credit for taking on the project. I don't think I would.

 

[DaveB2]

The 555 is capable of running on up to 18v iirc - though I admit it's been a while. As a thought that might bear a quick check with that simple switch you mentioned, will the fan slow down quickly enough to give you a "chuff" ?

Just looked on the Texas site and for the NE555 they say 16v recommended, 18v absolute max so 11.1 should be fine.

http://www.ti.com/lit/ds/symlink/ne555.pdf

 

[Neil Robinson]

As a thought that might bear a quick check with that simple switch you mentioned, will the fan slow down quickly enough to give you a "chuff" ?

I can't give a straight answer as it's down to personal preference.
I suspect some of the really impressive units such as those fitted to MTH Rail King One Gauge locos use a reversed dc voltage to brake (not break! ) the fan to give distinct chuffs at low speed.

 

[nicebutdim]

Instead of a microswitch, is there enough space to fit a reed switch and glue a magnet to an axle?

 

[tramcar trev]

Reed switch and Magnet? Now that's an idea worth thinking about, I like it..... "simplicity is best"!
I had thought that the fan may not stop instantly so that will need further exploration. Fortunately because the Baldwin Tram motor has "skirts" the chuffs do not have to be synchronous with the motion of the motion as the motion will be hidden from view and indeed may not even exist.... But using this idea the chuffs would end up as realistic as practical. Tram is stopped, smoke is building up in container, tram moves off reed is tripped for say 5 degrees leaving 360 degrees to stop the fan and get ready for the next chuff....
My other consideration is battery life. I'll have to have the heating element worked out so that it draws around no more than say 800mA but gets hot enough to evaporate the smoke fluid. If I wire this up behind the ESC no smoke will be made untill power is fed to the ESC, or if I have 2 channels smoke could be controlled..... To connect the nichrome to the copper wire I'll use 1/16" copper tube and crimp it.... All I have to do now is find some 30 - 40 mm copper or brass tube....

 

[tramcar trev]

Of course all this gives me white smoke, apart from shorting out IC's I dont know any way to make black smoke.... But then pale grey is going to be acceptable as this video demonstrates.
http://www.youtube.com/watch?v=WnPcduIGdWc

Ok some steam trams belched out clouds of black smoke but in the later years in Sydney they burnt coke and this is relatively smokeless or gives grey smoke.....

"Big Clive" has a great page about making your own smoke fluid; http://www.bigclive.com/smoke.htm I'll have a play with that too, considering what it is its an obviously "High" profit product....

 

[DaveB2]

It's probably been tried before and failed but have you considered using one of those ultrasonic foggers? I've never played with one but I'd assume that if you kill the power it stops instantly - I don't know if it starts up that fast or if you can control the volume of mist. If it was a possibility I understand they run for 1000's of hours before you need to replace the membrane, they're not that large, cheap (£4 biin on the bay) run on DC (the one I spotted was 24v though), no heat and run on plain old water.

Sounds too good to not have been done before if it would work.

Dave

 

[tramcar trev]

I did actually... but the mist they create does not go up rather it flows down like what it is, fog....

 

[DaveB2]

So... too good to be true, as expected. Ahh well worth a thought I guess.

Could you build something like a piston or diaphragm into the smoke chamber connected to a cam on the axle to make it puff ? At this point I'll admit I've no idea how much space you have to play with or the arrangement of those parts so I may well be talking out of the wrong hole.

 

[tramcar trev]

Hey that "dude" is cheating, plagiarising my ideas.... BUT HIS WORKS!!!!!!!!! I have yet to get off the ground but watching that DIY one serves to reassure me that I can build a custom shaped one to fit the smoke box... Making the container from metal is obviously the way to go to dissipate the heat.... Smoke quantity is dependant on current draw though.....
There is some informative discussion here; http://www.girr.org/girr/tips/tips3/smoke_tips.html
It would appear the commercial ones use a wire wound resistor with a fibreglass wick made from a piece of tubular fibreglass insulation.... So I have to find a 6R8 wirewound 2-3 watt resistor and some of this "coal" flavoured smoke juice; http://www.ebay.com.au/itm/JTS-MEGA...ALES-/130648467597?hash=item1e6b41688d&_uhb=1

 

[gregh]

... Making the container from metal is obviously the way to go to dissipate the heat....

I don't think you want to dissipate the heat except into the fluid. I'd be inclined to a metal, but well insulated container.

 

[tramcar trev]

Maybe a Tinplate enclosure wrapped in fibreglass cloth? Maybe work out exactly how hot its going to get then see if a "lost foam" technique can be used to make a fibreglass casing. I wouldn't think its going to be all that hot with the fan blowing air thru it.... The chap who makes the smokers for boats just uses a plastic box.... I'll have a fiddle and see what I come up with.... From looking at the videos clearly the Seuthe ones work well indoors but outdoors with a hint of a breeze not so well.....

 

[tramcar trev]

Yes Ross I had a look through a bit off "googling" I have done, however, I want CLOUDS of smoke, I want to be able to BELCH smoke of on command, not a little puff.....:-:-8D
The culminating please we all treasure beyond measure is the gratifying feeling that our duty has been done!!!!8|

 

[KeithT]

I wouldn't know where to start building or even fitting one of these but it seems to me that creating the chuff effect is v difficult. Would a slotted slowly rotating disc give the same result assuming it is possible to seal the smoke generating chamber preventing pressure leakage from the fan. Or is it just another impossible call on limited space in the boiler?

 

[tramcar trev]

Not sure Keith... But I'm going to be like a Terrier with a bone on this....

 

[Dtsteam]

Not sure Keith... But I'm going to be like a Terrier with a bone on this....

Well, burying it in the garden and then peeing on the spot isn't going to help much.

In truth, I think we're all keen to see how you get on.

 

[TLR]

I would have thought that to create puffing of the smoke something along the lines Triang Hornby did with their smoke generators ie a piston operated off of the main drive gear wheel with a tank of oil and a wire wound resistor that got hot and made the oil smoke, the more turns on the wire made it hotter and more smoke produced

Shaun