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Graphlite Flash Trigger Voltage
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45PSS



Joined: 28 Sep 2001
Posts: 3556
Location: Mid Peninsula, Ca.

PostPosted: Mon Oct 23, 2017 7:49 pm    Post subject: Reply with quote

My main concern is the current required to close the relay.
Perhaps a 3rd party flash for the DSLR will show the trigger current or possibly measure it as its likely much lower.
Second is the duration of the sync on the camera, will it be closed long enough to trip the relay?
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btvarner



Joined: 05 Oct 2017
Posts: 9

PostPosted: Tue Oct 24, 2017 2:47 am    Post subject: Who Is Right? Reply with quote

I am really getting confused. Look at this thread here:

https://photo.stackexchange.com/questions/93615/what-is-the-pc-port-amperage-trigger-limit-for-a-canon-dlsr

It really contradicts what I have been told elsewhere. Here is part of what was said:

"I can't say with certainty what Canon used in the 5D Mark III, but according to a discussion thread on Electronics point, the XT uses a 2SK2715 MOSFET for the flash trigger, and it's probably a good bet that they use the same part on all their cameras.

The 2SK2715 is made by ROHM Semiconductor, and according to the spec sheet, it is rated at 500V at up to 2A. Canon downrated their maximum spec to 250V, either as a hedge against slightly substandard parts or to allow them to source other equivalent parts that may have looser tolerances.

Either way, a part designed to handle up to 1 kilowatt triggering power laughs at your 0.3395 Watt triggering current requirements, and any even-semi-plausible replacement MOSFET that handles such high voltages will have similar specs. You should be fine."
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45PSS



Joined: 28 Sep 2001
Posts: 3556
Location: Mid Peninsula, Ca.

PostPosted: Tue Oct 24, 2017 6:51 am    Post subject: Reply with quote

My experience has been in repair, not design. I have identified failures that were a direct result of design flaw and what was happening so that a solution could be found.
Electronic components work best/last longest when their normal load is less than 1/2 of the rated capacity. I would not rely on the spec sheet of a component for the max load one could put on a circuit.
One would need to see the rest of the circuit and its configuration to know what the limits are.
Modern electronic flash still use 350 V to 425 V to the flash tube and in the event of a catastrophic failure a high voltage and or current surge can be felt at the trigger contacts.
I'm a Nikon/Large format person and Nikon recommends using their brand only.
The reason a manufacturer recommends their brand accessories is their designs will not overload their cameras if a catastrophic failure occurs.

It will be at least 10 to 15 days before I'm free enough to do any flash testing.
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