View single post by steve of oxford
 Posted: Sun Nov 11th, 2012 12:37
steve of oxford

 

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I can comment on this, having once blown a TTL (transistor-transistor logic) trigger circuit on a digital camera, fortunately a cheap one.

My advise is follow the general consensus here: either DC isolate the flash and camera, via slave trigger etc, or just don't risk it at all.

i wouldn't go by specs, even if they appear safe. Camera manufacturers 'could' make trigger circuits compatible with older blitz weapons, but they go for low level TTL/cmos, and often opposite polarity for no reason other than deliberate obsolescence, i.e. forcing you to buy a new flash gun.

Dislike the manufacturer's strategy as much as you want, but personally I think the risk is too great to start experimenting.......you 'may' have a 9v trigger on your old flash, but those old guns were capacitive energy store devices rather than direct inverters, so you can never be absolutely sure there isn't a bit of back-EMF spiking.... potentially enough to zap things. Only takes an old and weak decoupling capacitor somewhere and you've got a spike risk.