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-   -   Potenial dumb question re: trigger voltage (https://forums.steves-digicams.com/flash-external-52/potenial-dumb-question-re-trigger-voltage-132543/)

idahotb Nov 18, 2007 6:40 PM

Specifically, if one (not me- nope, no siree) has used an external flash of unknown trigger voltage successully in the past; does that mean that it will not fry the hot-shoe circuitry in the future? My limited understanding of electronics is that it would burn out the first time if it was going to; and it would not be a "wear and tear" situation if the potential were too great. Anyone have any comments on this?


Thanks in advance.

VTphotog Nov 18, 2007 7:09 PM

Maybe - maybe not. It depends on the components used, and how much the engineers have de-rated the components, and the manufacturing tolerances. Remember, electronics do fail eventually, due to component aging.

I would certainly recommend testing the voltage before using it extensively.

brian

idahotb Nov 19, 2007 11:10 PM

Thanks for the response Brian. I will get a multimeter and check it out. I still have a hard time believing the range of voltages (6-280 volts) I have seen listed for the 283. Especially since it as it runs off of 4 1.5 volt AA batteries.

Nov 20, 2007 12:32 AM

Just an aside....a Taser can throw out 20,000 volts off of 8 AA batteries. It's not the batteries, but the capacitor that will hold the charge.

VTphotog Nov 21, 2007 12:07 AM

Strobe type flashes have to have a high voltage stage to fire the xenon gas in the tube. There is an oscillator and transformer to do this. (the whine you hear when the flash is charging) The high voltage is stored in a capacitor until it's triggered by the camera. The trigger stage can be at battery voltage, or in the high voltage stage, or sometimes at an intermediate voltage. This is why, especially with older flashes, that you need to test it.

brian

geriatric Nov 21, 2007 6:33 AM

VTphotog wrote:
Quote:

Strobe type flashes have to have a high voltage stage to fire the xenon gas in the tube. There is an oscillator and transformer to do this. (the whine you hear when the flash is charging) The high voltage is stored in a capacitor until it's triggered by the camera. The trigger stage can be at battery voltage, or in the high voltage stage, or sometimes at an intermediate voltage. This is why, especially with older flashes, that you need to test it.

brian
Tubes require a very high voltage to trigger the flash, usually Kv`s, but is only a spike, but will damage the camera. The way designers got around this was the use of a thyristor in the trigger circuit.


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