So you didn't actually respond to my query but you confirmed what I thought: It's the "trigger voltage" of the transmitter that counts, not the trigger voltage of the flash unit, in the case of a wireless transmitter/flash setup. And yes, I agree—any modern equipment with transistorized trigger circuitry is going to be low voltage and safe, the old HV studio flash packs of the 1970s with 200-400V popping across a mechanical switching circuit should be a thing of the past.
If, however, you still have a couple of those old HV flash packs poking about that you want to use, for use with any modern camera like the Hasselblad 907x/CFVII 50c, you should put a "safe sync" unit in the circuit if you're connecting directly to the camera's sync terminal, something like the
"Speedotron Safe Sync Hot Shoe Adapter" from B&H, which provides the isolation from HV needed to keep the circuitry in the camera safe.
G
I did respond to your query... the pertinent value is the measurement of the *highest* voltage item
in the stack. If you have an X2N, Flex TT5, or equivalent
by itself, then it would be the only one that matters. Since they are battery powered, they are going to be low voltage with very little current, probably never more than the voltage of the battery powering it. It's also the case of the PW Plus III, where the trigger is the only item with no external shoe. In this case, it's 2.9V@10ma or so. Both voltage and current matter. That same 2.9V at 3A can cause quite a spark on mechanical syncs.
However, if you put a flash on the transmitter, then you should pay attention to the flash's sync voltage as it may be higher. If it's too high, it can short out the wireless trigger device and/or arc. Not too many devices are designed with discrete bipolar transistors anymore. Most are gated semis of some kind or another, but in a much smaller chip SMT format. That makes it much more likely to arc. If there were straight SCR/triac/bipolars still being used and they took a large voltage or high current, they'd just burn out or pop. With the smaller SMT or SOIC packaged designs, they can arc the device into a shorted state rather than open. It happens in power supplies a lot where older designs would just quit working, but newer ones get hot, melt, catch fire, or surge out the load. With older devices, you'd find pieces of the semis inside the casing. With newer designs, you'll see scorch marks, arc marks, or lots of magic smoke inside the case.
The other issue is if the highest voltage exceeds the lowest in the stack and/or has a very high current. Any arc it starts can forcefully burn with more current. Once it starts, it's harder to self-quench. Mechanical syncs are more tolerant of this as they will pit the coating slowly until they stop conducting which could be years. With modern, solid state syncs, they are much more delicate since one surge exceeding the device can cause it to blow.
When I shot the Flex system or played around with the cheap Yongnuo system, I often had flashes on the remote transceiver as a receiver. BUT, I usually also had a flash on top of the unit on camera too. That's the one that matters. If the voltage on the remote flashes exceeded the max of the receivers, then it would just blow that unit. But if the one on camera did the same, it could very likely go straight through to the camera's shoe so it is the important one to watch. These were all 580EXIIs so they were fine, other than the interference issue with PW. So glad to have gotten rid of those nowadays with the 600EXRT-II system.
useful stuff!
