PC-cord triggering of multiple flashes

[mmerig]

Yeah, I missed it -- it came in as I was writing mine but I did not check for new posts before posting mine.

As you say, the trigger sensitivity depends on the flash design. Were the Novatron strobes plugged into a wall socket versus some small batteries in typical flash units?

Could the 10 Mohm resistance (or higher?) in those Novatrons be for safety, to keep the current small so users would not get a shock from a sync cord, or fire the strobes via skin contact across the sync terminals?

I still think it is unusual for a digital voltmeter to trip a small flash unit.

 

[darkroommike]

It could be either voltage disparity or polarity (rare with the PC connection but still happens). Flash cords also create a tripping hazard, as others have said the best way is to use optical slave trippers, the Vivitar SL-2 works well with the Vivitar flashes and even has a 1/4-20 female thread on the shoe bottom for attachment to a tripod or light stand.

 

[Leigh B]

As you say, the trigger sensitivity depends on the flash design.
Were the Novatron strobes plugged into a wall socket versus some small batteries in typical flash units?

Yes, wall sockets.
The Novatron units have separate power packs and heads, at powers of 1000ws and higher.

Could the 10 Mohm resistance (or higher?) in those Novatrons be for safety, to keep the current small so users would not get a shock from a sync cord, or fire the strobes via skin contact across the sync terminals?

I never bothered to check the schematic to determine why the circuit works as it does.
The schematics are filed away. I may pull them out for a look.

I still think it is unusual for a digital voltmeter to trip a small flash unit.

It certainly would not be expected for small flashes.

Old large battery-powered flashes used 300-volt batteries, with that voltage at the PC.
Full bulb current flowed through the trigger contacts. These won't trip at 10 Megohms.

Modern flashes use many different trigger circuit configurations with different sensitivities.

- Leigh

 

[AgX]

It could be either voltage disparity or polarity (rare with the PC connection but still happens).

The PC-connector started as an inhouse standard by the shutter manufacturers Gauthier and Deckel. Meanwhile though it became a ISO standard. And I assume that not only covers the built and dimensions, but the polarity too.

 

[Leigh B]

And I assume that not only covers the built and dimensions, but the polarity too.

Why?

The PC was developed back when the only flash was wire that burned up inside a glass bulb.

Polarity in that technology was totally irrelevant.

- Leigh

 

[AgX]

I had it of the time of international standardisation, not that of the invention.

 

[chassis]

+1 Optical slave as others have mentioned.