5V smoke generator

[No72]

Though the smoke generator in my steam tram still works with some exuberance I will need a 5v version that can be switched on and off by the radio control. The electronic switch gives me 5V @ 1 amp...
So using Ohms Law 5V with a resistance of 8 ohms will draw around 650mA... I've experimented with an ordinary carbon film 1 watt resistor and that seems to get hot enough to produce smoke for the smoke oil so I wont have to wind an element...
If there is interest I'll post a "how to" as work progresses....

 

[PhilP]

Though the smoke generator in my steam tram still works with some exuberance I will need a 5v version that can be switched on and off by the radio control. The electronic switch gives me 5V @ 1 amp...
So using Ohms Law 5V with a resistance of 8 ohms will draw around 650mA... I've experimented with an ordinary carbon film 1 watt resistor and that seems to get hot enough to produce smoke for the smoke oil so I wont have to wind an element...
If there is interest I'll post a "how to" as work progresses....

I would use a wire-wound resistor.. You will eventually 'burn' the outer covering off the resistor.. This will not really affect a wire-wound unit, but a carbon film resistor will probably fail a lot sooner.

 

[Greg Elmassian]

Yep, been there and tried that. Exactly what Philip says.

You can buy a wirewound resistor, and some people crack off out outside exposing the wire, which allows fitting the wick more closely to what is getting hot.

Greg

 

[No72]

Yes.... Hmmm it seems so have I. But before I try to crack the ceramic case of a wirewound resistor I'm going to try a metal film one and see how I go. I did wind my own... I need around 8 ohms resistance for it to work off 5v. Look here way back in 2013.... http://trevs-tramway.blogspot.com/2013/08/the-project-is-smoking-now.html
Maybe you could grind the ceramic outer off with a diamond burr?

 

[Greg Elmassian]

Nope, you wind up cutting into the wire, use a carbide cutoff as a disc sander, or a carborundum grinding wheel.

I find just putting it in a vise and slowly tightening until you hear a crack works fine.

Greg

 

[PhilP]

Nope, you wind up cutting into the wire, use a carbide cutoff as a disc sander, or a carborundum grinding wheel.

I find just putting it in a vise and slowly tightening until you hear a crack works fine.

Greg

Wot Greg says... Always worked for me..

 

[Greg Elmassian]

If you use pliers, it's impossible as a human to instantly release pressure the instant the outer shell cracks.

With a vise, it won't "keep squeezing" if you take it slow.

Greg

 

[No72]

I would use a wire-wound resistor.. You will eventually 'burn' the outer covering off the resistor.. This will not really affect a wire-wound unit, but a carbon film resistor will probably fail a lot sooner.

Alas the only wirewound ones I can get are the square ceramic ones.... So I'll use 3 watt metal foil and see what happens. I may try to preremove the outer coating with maybe paint stripper, I dont know what the coating is, I expect epoxy but its flameproof... I'd expect a 1 watt resistor to fail if it had a 3 watt load across it. With a 5 v supply and an 8.2 ohm resistance that's just a tad over 3 watts.... Other wise its back to "wind my own".

 

[Greg Elmassian]

The square ceramic ones break open just fine, by the way, they are round inside.

Also you normally derate a resistor by half...but you want heat, but metal foil is just that foil, not wire.

get the square one and crack it open.

 

[No72]

The square ceramic ones break open just fine, by the way, they are round inside.

Also you normally derate a resistor by half...but you want heat, but metal foil is just that foil, not wire.

get the square one and crack it open.

Whats your technique? I tried on a few and they just shattered leaving the core snapped and the wire still partially embedded in the inner ceramic.

 

[PhilP]

Whats your technique? I tried on a few and they just shattered leaving the core snapped and the wire still partially embedded in the inner ceramic.

Do not try to do this with pliers... You just can't instantaneously stop squeezing..

Use a vice, nip it up, then fraction of a turn, and pause.. Fractions of a turn, and pause..
Quite often, it will crack, as soon as you touch the handle, to apply more pressure.
Once it has cracked, stop and see if you can get the outer ceramic off. - You are not trying to pulverise the outer.. Think shelling nuts.

It sounds like you are being a little heavy-handed with the vice??

 

[Greg Elmassian]

Whats your technique? I tried on a few and they just shattered leaving the core snapped and the wire still partially embedded in the inner ceramic.

POST #5 and what Philip said... easy does it.

I'm talking about the square ones:

Buy from mouser Australia.... a couple of bucks... what is inside is some ceramic filler and a round wirewound resistor.

The outer "shell" just cracks open.

Greg

 

[No72]

POST #5 and what Philip said... easy does it.

I'm talking about the square ones:

Buy from mouser Australia.... a couple of bucks... what is inside is some ceramic filler and a round wirewound resistor.

The outer "shell" just cracks open.

Greg

Exactly the style I tried to open.... Mine were from Jaycar...I have a diamond wheel for the dremel, I'll try scoring the outer with that first...
Now onto the wick. I found a product today that its claimed to be spun from rock and withstands very high temps, $5.95 form Jaycar. It looks to have superior "wicking: qualities than the fibreglass insulation tube I did use....
https://www.jaycar.com.au/high-temperature-basalt-fibre-sleeving-6mm-x-1m/p/WS5511

 

[No72]

SUCCESS!!!! but it looks like I'll have to go back to 12V. at 5V I draw more current to get the same amount of smoke so It looks like my 5v RC switch will have to control a relay to get the smoker to work...

 

[Greg Elmassian]

I see the higher temperature, but it appears to be fewer and coarser strands and not intended as a wick.

"Tiki Torch" wick below, much finer, and by normal laws of physics should have superior capillary action.

Let us know how it works out.

Greg

 

[No72]

So after practical experiment to get the amount of smoke I need if I use 5V i have to use 5 ohms which is 1 amp and 5 watts which cant be switched by the 4 channel RC switch I have. So its back to 12V and the switch will activate a relay so I'm back to where I started with 12V, 12 ohms and 1 amp ..... However I have made the new one much smaller its 35mm x 60mm x 35mm high. The high temperature "spun Basalt" works well as a wick, its neat and easy to fit into my little device. I'm out of resistors to crack open so I'll get some at some time and finish this off. I have yet to install the tubes that direct smoke to the cylinders where it escapes out of the "drain Cocks".....

POST #5 and what Philip said... easy does it.

I'm talking about the square ones:

Buy from mouser Australia.... a couple of bucks... what is inside is some ceramic filler and a round wirewound resistor.

The outer "shell" just cracks open.

Greg

I was using the wrong technique, Vyce worked well...

 

[No72]

Smoking... not good for your health. Works though....

 

[PhilP]

Interesting..

Would you have a picture of the inside of the bottom 'half' of the unit?
Perhaps a 'build-thread'? - If you have the time..

 

[No72]

Interesting..

Would you have a picture of the inside of the bottom 'half' of the unit?
Perhaps a 'build-thread'? - If you have the time..

Yes of course I do, remiss of me not to post it.... However I'm changing the design yet again the reservoir will come up closer to the underside of the lid. This is to try and prevent spilling of the smoke fluid. I noted under the "shake around during use" test that fluid can spill... Alternately Put the fan back into the lid and use the bottom of the box as the reservoir. and leave a longer wick that can virtually cover the bottom of the box. Also I have not placed the 2 bits of tube that conduct the smoke to the cylinder drains so this is the "diesel" version ( though it would be an ill diesel that made this much smoke) LOL.
Maybe if you look here you will see my trials and tribulations back in 2013,http://trevs-tramway.blogspot.com/2013/08/the-project-is-smoking-now.html?q=smoke its just a matter of adapting the sizes of box etc to suit ones individual needs, this one has to be small to fit in the smoke box of the Baldwin boiler. If you are using radio control you can also control the output by using an elcheapo ESC on a spare proportional channel so you can have just a wisp while coasting along on the flat and heaps while powering up a grade, the one I use is here; https://www.ebay.com.au/itm/10A-Bru...997899&hash=item3acb8221c0:g:UNYAAOSwUfNXRqWi use the non braked version and they seem to work OK on 12v if you are only pulling an amp.

You do need a sealed box to prevent the egress of smoke where you don't want it. I'm also going to try with an ABS box to see if it can handle the warmth...........

 

[PhilP]

Thanks for that... An interesting read..