the bulbs light up at 1 volt ok. A single flashlight battery will light them, but two would give you a safety factor.

To make, snip off the round knob so you can put AP in the bulb down around the filament.

You can also use black powder or any flamable powder instead if you merely want it to light your primary expl that is in some other form.

If you put all the AP the bulb will hold, you will have about a number 3 blasting cap. It needs some more outside this bulb to get up to number 6, and needs about a teaspoon to reach #8 cap capability.

You can twist the bulb leads onto a long pair of wires like lamp cord, and be a safe distance away when you touch it off.

For big blasts, buy a 250 ft roll of 2 wire #14 house wiring, for about $20, and use it as an extension onto your shorter lamp cord testing cable. You can re roll it up many times, and when it gets too stiff to roll up any more then use it as house wiring around your shop etc.

If you want to be sure it will not fail to fire, use higher voltage, even plug it into the house wiring, if batteries are not available and a outlet is.

A good way to test in a neighborhood is to dig a pit and bury a 6 gallon plastic bucket in it. make a cover out of an old tire filled with concrete so you have a heavy thick lid with the tire as outer rim.

Just lay the tire on a flat surface and fill it with concrete till its full and makes a large thick lid.

put your blast in the center of the bucket so lots of air is all around it, and it is on a pedastal about in the center of the bucket.

lay the lid on it and use electric firing as above.

Test it with small amounts until you discover the most it can take without making more noise than you want to make.

if you want to test larger amounts, do the same but use an old washing machine inside porcelean tub instead of a bucket, and the tire will still cover it.

Do make sure the tire is down in the dirt well, for any air leak will let lots of noise out. Best is to have a little ditch all round that the tire fits down in and wiggle it around in soft sand in the ditch so it seals well. This way you can whack off test explosions right outside your lab door, or in its floor even if its dirt floor.