Electronic – How to reliably and safely recreate a blue smoke monster for a workshop


First and foremost, I'm going to say that I do and plan to continue to follow all safety best practices for working with electronics. I'm also a relative newbie, so I don't have a lot of experience diagnosing WHY things fail, and especially not in creating deliberate types of failures.

That being said, I'm helping a friend make a few short videos to augment an electronics workshop he does. The workshop is a very basic overview of electronics, more to get kids interested in the possibilities than an introduction to electrical engineering. With my background in graphic design and A/V production, he's enlisted me to make his powerpoint presentation more dynamic. I'm adding some short animations and video clips illustrating electrical concepts.

One video that I want will show power being applied to a circuit and then having the circuit smoke and fail after a short delay. We have a couple things we want to communicate:

  1. electricity is dangerous (if this happens on a small scale, imagine the disastrous results on a larger scale),
  2. the delay will show that failures may not be instantaneous, BUT
  3. don't let that stop you…everyone's encountered a blue smoke monster, fix it and move on.

LED flareups (see how easy it is to burn out an LED by simply mixing up where the anode and cathode land?), aren't nearly as visually dramatic as I'd hoped, but I do recall making something from a kit about a year ago that just smoked like crazy once I plugged it. I'm not sure what component failed, and it's dead on my workbench waiting for a diagnosis…but it looks AWESOME. So I'm looking for a circuit; I envision a PCB or breadboard with a couple components, I attach a power source (AA or 9v battery), and after a few seconds, smoke. If there's an LED that blinks out after the smoking begins, illustrating that the circuit is dead…that'd be awesome. And, being the perfectionist I am, I'd like to be able to reproduce it reliably for multiple takes.

Any suggestions for a circuit that'll do this without unnecessarily endangering myself?

Best Answer

As usual, you need look no further than the eevblog exploding capacitors video


-wear safety glasses

-keep flammables away

-test out everything first with a proper DC voltage supply that has effective current limiting and safety measures

-do it in an actual lab that has real safety and hazard precautions

Not following any of the above is probably not smart [but probably how I would do it anyway ;).] With a low voltage, the biggest danger is probably to actual projectiles.

I would just reverse bias a low voltage cap (for the most flare up). You can put a diode somewhere after it that will 'turn off'. I would also put a current limiting circuit at the input to kick in after the cap goes, for safety.

You could probably get some nice smoke from any IC that you overvolt with a decently rated supply current.

You may need more than a single AA or +9V to get this effect.