The E Side Of E Firing

The E Side Of E Firing

by: Matthew Kleinmann

Over the last year or so we have gone over going from an e match to a regular fuse, and types of fuse.  We have not covered the electronic side of setting up multiple e matches. Let’s do just that.

When you connect multiple electronic devices up together, you have a choice of how to connect them.  Most pyros agree that e matches should be connected in series.  This can seem a bit complicated to the new user, but it is pretty simple.

The textbook example of devices being connected in series are the small christmas tree lights.  If one light goes out, the entire string goes out.  The current passes from one device through the next, continuing on in that manner until it reaches the last device.

To do this with e matches is pretty simple.  Let’s start with a really easy case, where you have two devices you want to go off at the same time on the same cue.  You have two sets of wires, one pair coming from the first device, and one pair coming from the second device.  The easy way to do this is to connect one wire from each of the two devices to one of the terminals on your firing system.  That leaves you with one wire from each device that is unattached.  Those two remaining wires, get attached to each other and the junction covered over with a little bit of tape.

If you had three devices, assume the case of two devices, but instead of connecting the two free wires left at the end together and taping them up, one wire from each of the pair going to the third device goes to the open wire of the first and second devices, and they get taped up.

This technique can be expanded upon.  The maximum number of devices depends on your firing system and the matches that you are using.  I have a friend who had a big stash of e matches and we did extensive testing with my e firing system for both range and the number of e matches that it could fire.  We stopped testing at 5.  My system could reliably fire 5 e matches on one channel.

Some of you may be asking why we use series and what will happen if you don’t.  Some people may also have experience with high power rockets where it is not unusual to connect them in parallel.For fireworks, most of the e firing systems use a high voltage discharge type firing system.  This works by having a circuit in the firing system charge up a capacitor, and when you fire the cue, the capacitor is discharged through the e match.  This is generally both a high voltage and a high current pulse.  The pulse does not last very long before the capacitor is discharged.  This works well with long lead lengths often encountered in fireworks.  Also remember in the pre wireless days, it was not unusual for the high voltage to have to go through hundreds of feet and multiple cables and multiple connectors before even making it to the e match.  

In rocketry, generally there are not the long lead lengths.  Most launch systems have a relay near the launch pad and have a battery capable of putting out a low voltage, typically 12V but at very high current.

Take a chance on electronic firing. It’s a great way to spice up your show and help you shoot like a pro.

Matthew Kleinmann  Is a professional, licensed pyrotechnician and a staff writer for Mess's Fireworks