I'm involved with an amateur theatre company (I do lighting, audio etc…) and would like to simulate a switch short-circuiting. I have also done a bit of magic in my time and have used "spark ejectors".
Because I would like to build something in to the scenery, I'd quite like to build a custom spark ejector (that I can then fill with flash paper and "sparkle additive" and power with 1.5V AA batteries, just like in the commercial versions). Looking at the commercial hand-held devices, they seem to be a fairly simple coil underneath the chamber that you then load up with the "payload".
Does anyone know of a tried-and-tested circuit diagram which would let me do this? I've done quite a bit of work with MCU's in the past and am well aware of the potential safety issues with these devices!
Best Answer
The most common method for electronic, handheld stage ignitors is to use a model engine glowplug. Choosing an appropriate glowplug, with 6V (often using four 1.5V N size batteries) will produce a quick heating action with enough heat to ignite flash paper or flash cotton.
The circuit is simple - batteries, momentary pushbotton switch, and glowplug all in series.
Note that the action isn't instantaneous, so some practice with the device will be necessary to get the timing done right, but it is still very quick. It's not so slow that an accidental press will never set it off.
You can do an internet search for "RC glow plug" to find a number of sources. You'll need to do a little research and probably some testing to get the right glowplug/battery combination that will give you the speed and heat you're looking for.
I assume you are aware of the potential dangers of such a device. Carrying around even small explosives can create severe wounds, loss of limbs, and fatalities, even under good conditions. This is not a device to be taken lightly, or used by someone who is not a trained professional in using pyrotechnics. Don't hand this to an actor after a few minutes training and expect safe use.