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Old camera speedlight low voltage trigger conversion

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StillTrying:
When the flash's trigger transformer and 380V charged cap are shorted to gnd to create the 4kV spikes, the current is 10s of Amps for a few us. So don't worry about it. :D

cprobertson1:

--- Quote from: StillTrying on June 20, 2019, 01:33:51 pm ---When the flash's trigger transformer and 380V charged cap are shorted to gnd to create the 4kV spikes, the current is 10s of Amps for a few us. So don't worry about it. :D

--- End quote ---

Those numbers scare me... :-BROKE

I haven't managed to get a good reading on the trigger current I'm afraid. I was getting figures between 30 and 100 milliamps with the multimeter on min/max mode, but if there are spikes I wasn't able to read them properly... the TRIAC is rated to 1A though, so if it's less than that we should be okay for the most part (excusing voltage spikes) and the transistor driving it is rated at 300mA, so, hopefully, I'm not driving anything into the ground (or rather, with the low duty cycle, it might survive the abuse long enough that it won't matter.)

Time will tell xD

StillTrying:
Most things in a flash are at unusual levels. When even a small tube lights it got about 90V across it and about 100A through it, which is why it makes a nice pop! The main 350V storage cap doesn't like it much either. :)

The pulse currents of thyristors and similar are very high, and when over their rated voltage they tend to just switch on prematurely with no lasting damage.
I'll try capturing the few us of trigger transformer current later.

cprobertson1:
I do have to say, that pop is amazing! ::grins to self::

Oh, and the coil whine when it charges!  :-+

Actually... er... two moments... yeah, that whine doesn't stop in the Hanimex unit even after the "ready" light comes on. I wonder if it's _meant_ to do that; or if its leaking charge and needs to continually recharge the flash capacitor once it's at voltage...

Actually, I might refurbish all the caps anyway: I'm sure it couldn't hurt. Unless I touch them - youch!

Zero999:

--- Quote from: StillTrying on June 20, 2019, 01:33:51 pm ---When the flash's trigger transformer and 380V charged cap are shorted to gnd to create the 4kV spikes, the current is 10s of Amps for a few us. So don't worry about it. :D

--- End quote ---
But the energy delivered to the trigger transformer is tiny. A modest sized TRIAC should be able to handle those numbers for a short period of time, without being damaged.

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