SparkFun Forums

[PhilipB]

Hey Friends,

I'm looking to build an incredibly thin heating element with a few drops of mineral oil on top that get hot enough to produce smoke. It's a special effects prop for a play, and a little bit of fog/smoke needs to come out of a very thin object.

My initial thoughts were a bunch of coin cell batteries in parallel up against Nichrome foil to produce a heating element, and then just a small amount of mineral oil on the surface. Build in a switch, the thing gets really hot, the oil reaches it's smoke-point, and then gets switched off.

I'm looking at coin cell batteries like this Sparkfun item:
https://www.sparkfun.com/products/11928

Does anyone have experience with something this? Do you know how many batteries I'd need to get the heating pad hot enough? I'm pretty sure Mineral oil's smoking point is around 200°C.

I would love any help! Thanks so much!
Phil

[lyndon]

Similar topic came up about a year ago. Search "smoke" in the forums to find the solution.

[PhilipB]

Thanks lyndon. That low-power smoke machine is definitely headed in the right direction and is giving me some ideas. However probably a bit more powerful than I actually need. I would only need one single moment of smoke to emerge. So the battery capacity can be significantly smaller, and the amount of fluid can also be quite small.

When I plug in some specifications into a Nichrom Wire calculator, I can get 5 inches of 30 gauge Nichrome wire up to around 280°C with 3 volts and 1.1 Amps.

That sparkfun battery is rated at 165mAh, I wonder if I could push it to 1 amp for a short enough period of time to get the smoke hot enough? Any idea on the maximum available current of those little coin cell batteries?

I'm not allowed to have any sparks or fire present which is really whats leading me to this heating coil option.

[notexactly]

Coin cells tend to have pretty high internal resistance, so they might not be able to supply enough current. Just something to keep in mind. (Maybe one of the thin rechargeable batteries would be better.)