High trigger voltage for external flash..... is it really harmful?


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mpenza

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For cameras using PC Cord or Hot shoe to sync, is it really harmful if the trigger voltage is 200+V?

I measured the resistance of the "socket" of my camera and found that it's open circuit normally and when it sends a trigger, the resistance is in the region of Mohms (I was using a multimeter and couldn't capture the exact changes in resistance).
 

ckiang

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Originally posted by mpenza
For cameras using PC Cord or Hot shoe to sync, is it really harmful if the trigger voltage is 200+V?

I measured the resistance of the "socket" of my camera and found that it's open circuit normally and when it sends a trigger, the resistance is in the region of Mohms (I was using a multimeter and couldn't capture the exact changes in resistance).
Whether it's harmful will depend on individual camera's specs. For Nikon Coolpix series, the acceptable trigger voltage is about 200V. For Canon G1/G2, I read it's like 5V only. Using a flash with a trigger voltage > specified will result in damage to the camera's flash circuitry or the whole camera. Be careful.

Resistance of the socket of the camera is not an accurate way to test. Most cameras use an electronic switch to trigger the flash, and the contact time is very, very short, so you can't really measure it. For mechanical cameras, a mechanical contact switch is used.

Regards
CK
 

mpenza

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Thanks. I'll see if I could find another way to test... if only I have an oscilloscope, I could measure the waveform with respect to time.
 

ckiang

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Originally posted by mpenza
Thanks. I'll see if I could find another way to test... if only I have an oscilloscope, I could measure the waveform with respect to time.
Oh, trigger voltage is simple enough to test. Put the Multimeter to VOLT mode, turn on the flash and let it charge, then put the negative probe on the side contact of the hotshoe, and the positive probe to the centre pin.

Regards
CK
 

mpenza

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I got that.... reads ~240V. I just wanted to see if there's any way to test the characteriestics of the camera socket.
 

ckiang

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Hi,

Wah, that's very high. You might want to get the Wein Safe-Sync which will isolate the high trigger voltage from the camera. Not sure where it's available in Singapore though.

Regards
CK
 

mpenza

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I did see something like this in CathayPhoto. But the listed price is quite high... higher than my flash :p
 

ckiang

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Originally posted by mpenza
I did see something like this in CathayPhoto. But the listed price is quite high... higher than my flash :p
How much? Alternatively, if you are an electronics hobbyist-type person, you can build one yourself too. I saw a couple of circuits for this on the net before. Just need an opto-coupler and some other small components.

Regards
CK
 

mpenza

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the listed price was $75 if I'm not wrong. will search for something :) thanks for your advice :)
 

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