DIY 360 VDC Power Supply for Vivitar 365 head

Discussion in 'Lighting Equipment' started by Aoresteen, Sep 4, 2013.

  1. I've never seen a capacitor of that value with a 330 volt or greater rating. I suspect it would be the size of a dustbin. Low ESR capacitors are preferred for xenon tube driving too.

    330volts is the 'standard' flash-tube potential for speedlights. Though some may run a bit higher. Old Metz units for example.

    I think you could fire a small xenon tube with a terminal voltage of 200volts or maybe less. No idea what the efficiency or colour spectrum would be like though.

    Small studio monolights in the UK tend to simply rectify the mains 230 v ac (RMS) to give a roughly 320 volt DC supply to the storage capacitor. But there's no real world standard for high energy studio strobes.
     
  2. Well the capacitor that I was refering to were 5 2000uf in parallel and they are rated at 600V. They are quite large about 6 in tall with diameter of 3 in. The power supply would charge them up to 340VDC. But supplying the power supply were 220V 3 phase and has a 100A circuit breaker.
     
  3. OK. That would give you nearly 600 Joules of energy.

    The biggest single (modern) flash capacitors I've seen were Elinchrom 3,300uF at 350v.
     
  4. This is an old thread but I will post anyway....someone may benefit from it. I run a Vivitar 365 on 12v transformer which I built from an old battery charger. The flash is a powerful beast and contrary to popular misconception, it runs on 365 volts DC (hence the model name Vivitar 365). The DC transformer puts out 20 Amp and the flash is happy with about 10 Amps when charging the large capacitor after full power discharge. Recycle time is just under 4 seconds after full power discharge, on auto setting it can keep up with my Nikon D2X (about 6 fps). I also run the system on 12v 15 AH SLA with no issues. Its perfect for location shoots or to overpower the sun if used with High Speed sync remote trigger. An absolute bargain at only $5 dollars I paid for the flash and total of $15 spent on modifications to suit my needs. Highly recommended
     
  5. - Now that I'd like to see!

    Maybe you mean a 12v/20A power supply (PSU)?
    There's no such animal as a DC transformer. All transformers require AC to function.

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

    Sunpak AZ3600 hammerheads of similar age have a trigger voltage of around 330 volts on their P-C cable. Although that gets dropped to around 12 volts when an accessory hotshoe adapter is fitted.

    The similar-looking Sunpak 4500 has a lower trigger voltage and higher output, but is less flexible in its modes and AA settings.

    Then there's the Metz 60CT range that use a shoulder-pack supply. Their true output GN is around 45 for 100 ISO/metres.

    Any of the above can be bought very cheaply these days.
     
  6. According to this site, it's around 46 volts.

    Photo Strobe Trigger Voltages
     
  7. 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.
     
    Last edited: Oct 10, 2018

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