Continuity testers

At least you sit next to the explosives guy :)

If you want a handy-dandy continuity tester check out Pratt Hobbies Pocket Igniter Tester:

Not that different from what I built a LONG time ago, except mine used a 3v button cell instead of the 12v battery. In fact it's nothing more than a 3v lithium button cell taped to a 3v piezo buzzer, and a couple micro clips. The lithium cell couldn't supply enough current to fire an ignitor even under a direct short.

Thanks, Bruce! I made another dozen of the little critters last night. They are pretty similar to the design Bob describes, except that instead of depending on the battery I rigged a circuit. It's the same simple transistor-resistor setup I use in my launch systems, and the current sent to the igniter depends on the resistor. Works on everything I've tried, including some bare electric match heads I had left over from experiments at making my own. I can't even see those bridgewires without a magnifier.

I have never seen the gadget Fred describes at the start of the thread, but I have a couple of units that are sold to fireworks folks that have a 9v square battery and an LED. The circuit looks pretty similar. I could have made the PIT with a 9v battery, but I have a whole ton of N cell battery holders for Microbeacons, and the philosophy of using the battery holder for a spine, potting the fragile stuff in hotmelt glue and wrapping the whole business in heatshrink appeals to me. It's simple and tough, and I can make 20 or so in a pleasant evening. Besides, those little 12v batteries are cheaper than 9v Duracells, and one should last a lifetime in this thing. In fact, you could use a battery that has flown a few times in an Adept altimeter and isn't trustworthy for flight anymore.