saefroch wrote:Might it be possible to dump a photoflash capacitor into another transformer coil to produce a high-voltage current for ignition? Or would that probably just cause arcing all over the secondary?
Yes, it has been done a number of times with an automotive ignition coil. You'll typically get an output voltage of ~30kV from a 300-350V input.
The setup is quite bulky
, but it's highly effective for low to moderate mixes.
That's a negative.
Coil, capacitor, charging and pulse circuit are present on my hand.
Bottom wires are 1.5 to 3VDC battery power
Top wires give off ~25KV pulses with that particular setup.
If anyone hasn't yet seen it, spark demo: [youtube]http://www.youtube.com/watch?v=mOpsWctz9wk[/youtube]
The main space saving is in the coil.
Yes a full blown ignition coil the size of a pint can will be capable of higher voltage output.
However to get a high spark repetition rate in a small circuit you don't want to go mad on the voltage because that needs more energy, higher current rated components, maybe even heat sinks. All of which is a major drag.
So if we don't want to try for 100KV we can do fine with a miniature ignition coil which is practically identical to the HV coil found in a stun gun and in fact commercial gas ignition devices. In the clip it's doing about 25KV.
You can still try for higher voltage output with a small circuit like this, you just trade off spark rate for higher voltage.
I've tried up to 45KV with the same circuit by changing the spark gap that pulses to the HV coil but the spark rate is lowered significantly.