Electronic trigger (Explosion)

Diwali season is here, the festival of lights, joy and happiness. So what better way to DIY this diwali than to make an electronic trigger for diwali crackers and explosives.

I gave up bursting crackers a long time ago for a variety of reasons (air and noise pollution, realisation that it is pretty pointless not to mention unsafe..). However, I am a bit of a pyromaniac and enjoy safe, harmless crackers (and small bombs) in limited quantity. Also, have wanted to record explosions and watch the firecracker tear itself apart in slow motion. So I made a simple setup with some wire, a heating coil from an old iron press, and a dimmer to act as an electronic trigger.

When current flows through the heating coil, it generates heat, following Joule’s heating law. Heat generated per unit time is proportional to the square of the current flowing through the heating element. <  H= I^2 xRxt  > The dimmer is in series with the heating coil, so I can adjust the current through it and hence the heat generated in it. When the coil heats up sufficiently (above ignition temperature), it is able to ignite the fuse wire of the firecracker (or a matchstick head) and voila!

This trigger is important for video recording as it is very difficult to light a firecracker by hand (and then run away) without disturbing the position of the firecracker or the camera or the lighting. Using this setup, I recorded a few small firecrackers exploding and a big one blowing up an apple!

So here’s how I use it:

  • Make sure everything is in position (including Camera)
  • Wrap one turn of heating coil around the firecracker fuse wire
  • Retreat to a safe distance and turn the switch on
  • Allow a small amount of current to flow through the heater coil for a very short time (just to get it red). Current is switched on and adjusted with the dimmer knob (extreme left for off, turning right reduces resistance, increasing current, extreme right for full current)
  • The fuse wire lights up and the firecracker explodes.