This writeup will describe how to make a timer to set off a Pyrotechnics
How timers can be useful
In general, using timers when working with pyrotechnics is not a very good
idea - the timing of performances is rarely accurate, and if a performance
is aborted, the prop is still active. Also, if an actor is too close to the
prop, you can't stop the prop from igniting. bad idea. Using radio
or remote controlled detonators makes a lot more sense.
How to make a timer
The easiest (and cheapest) way to make a timer is to get one of those cute
little digital kitchen timer clocks - the kind where you punch in a number
of minutes and press start, and it starts beeping after X minutes.
What you do, is that you pick the clock apart, and remove the (usually a
piezo-ish) speaker that makes the sound. You now want to get the cables
that went to the speaker-thingie (if there are none, solder on some - this
might be a little tricky, depending on the timer) Then, hook it up as follows:
| +--------+ |
| | | |
| +--------+ |
Battery | +--+------------
Usually, your kitchen timer alone will not deliver enough power to set off
the fuse by itself, but this can be resolved by using a simple transistor
That was it, really! No ticking clocks, no big bars of dynamite.. With some
practice, you can fit this whole mecanism (and a load of actual explosive
material) in a box the size of a regular coke can.
A word of advice
This, like the Motion Detonator is a self contained system. That means
that if you decide not to use the prop, you are in trouble - if there is less
than a minute left untill the timer goes off, it is a bad idea to go close
to the prop. At the same time, some timers have the bad habit of going "beep"
when you start the timer. Usually (i.e when you use the timer for what it's
intended) this is annoying. If the "beep" sets off an explosion
between your hands, it's more than just annoying. Make sure that your timer
doesn't go "beep" when you press start.
Usually when I make these kinds of props, I include a safety loop. In other
words, add a switch and a LED. The LED is coupled straight to the battery,
and lights up when the switch is on. This way, you can easily determine if
the prop is "armed" or not. This also allows you to use timers that
say "beep" - you just start the timer, and then flick the
In any case, as mentioned, timers are a bad idea.
Back to the node on pyrotechnics
Please read the disclaimer
. Also, make sure you have read the Pyrotechnics
. SAFETY FIRST