Strobes and Sparks---TJ Byers

[Smitty]

I'm experimenting with disposable cameras and saw the Q & A article in the Dec. 2001 issue. How can I modify a disposable camera unit to produce streaming sparks between 2 probes? Any suggestions or a circuit is appreciated.

[Chris Smith]

Technically you cant. The strobe unit stores up a large cap into a value of around 500 volts, several hundred micro farads and then applies this voltage / current across a "Gas Discharge Gap" [xenon tube] that wont light at this low voltage on its own, and through the use a micro sized step up transformer it induces a extreme tiny current in excess of 3kv to 5 kv which jumps the gas and triggers the Gas in the tube to create a path for the lower voltage that contains a high current. [Lightning principles with leader spark] The charge rate of a flash is very slow, meaning that if you dump the load as fast as you make it, the voltage will be only around 100 volts constant, until you accumulates it for several seconds or even minutes. Think of it to be a garden hose filling a large water tower, slowly. When you wait, you have a lot of energy, but second by second, its just a garden hose full of a small quantity energy. If you want sparks, a 555 oscillator driving a modern ignition coil is the way to go. A pseudo Tesla coil [solid state] cant produce voltages in excess 300kv and light up fluorescent tubes with out electrical contact up to 5 feet away easily using a coil with less than 10 windings in and 500 windings over a tube length of 18 inches. About 75 kv in, about 300 + kv out. More windings, more voltage.