DIY 360 VDC Power Supply for Vivitar 365 head

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What's the trigger voltage of that old Vivitar BTW?

According to this site, it's around 46 volts.

Photo Strobe Trigger Voltages

You need to take those Botzilla figures with a large pinch of salt Dennis. The reason being that they're submitted by random people using unknown equipment, and with an unknown degree of expertise.

Most old trigger circuits have a resistor of several megohms in series with them. If this is measured with a multimeter or DVM having the common 10 megohm input resistance, a potential divider is formed, which gives a totally inaccurate measurement of the true open-circuit voltage. And always on the low side.

To get a true reading of the trigger voltage an expensive electrometer instrument is needed. Or you need a known high value of resistor, and to take two readings; one with and one without the supplementary resistor in series with the meter. Then two simultaneous equations have to be solved to find the real voltage.

I severely doubt that many contributors to the Botzilla 'database' have the equipment, skillset and inclination to carry out such a proper test of the trigger voltage.

My own findings are that simply poking a multimeter onto the hotshoe or P-C plug of an old flash can give a reading that's out by anything from minus 30 to minus 70%. And that's with a known 10 Megohm input DVM. A cheap meter with only 1 Mohm or 100 Kohm resistance will be far less accurate.

I've attempted to convey these concerns to the compiler of that erroneous Botzilla list to no effect so far.