John Seaman Posted September 26, 2022 Share Posted September 26, 2022 This little three colour flashgun came to me with a job lot of other stuff. It's unbranded but I later saw one on the auction site. It's a Lomography Colorsplash. I have a habit of checking trigger voltages and found that this gun, powered by a single AA battery, has a scary trigger voltage of nearly 1000V, by far the highest I've seen. And that's using a moving coil meter, heaven knows what the open circuit voltage is. So it's heading for the bin, but just in case you are tempted to use one of these on a digital camera, don't! Here it is, by the way the centre contact is negative on these. 1 Link to comment Share on other sites More sharing options...
Niels - NHSN Posted September 26, 2022 Share Posted September 26, 2022 There's a selling point on theBay - "Highest Trigger Voltage Ever!". Someone's got to want the "best" flash in that regard;) 1 Niels Link to comment Share on other sites More sharing options...
JDMvW Posted September 26, 2022 Share Posted September 26, 2022 Thank you very much! Some older data on the problem of high trigger voltages on pre-2005 strobes Photo Strobe Trigger Voltages Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted September 27, 2022 Share Posted September 27, 2022 (edited) Some older data on the problem of high trigger voltages on pre-2005 strobes Photo Strobe Trigger Voltages Oh no! Not a resurrection of the Botzilla list - Please! A good idea, but a slapdash execution. The issue is that hardly any of those Botzilla trigger voltage measurements were done properly or consistently. Even a 10 megohm input DVM draws some current, and given the high internal resistance (> 2.2 megohms, typical) of 1970s or 1980s trigger circuits, this can lead to a 50% or more error between the measured voltage and the true open-circuit voltage. And it's the O/C voltage that can puncture the insulation of a semiconductor device and destroy it. Typically, any older flash that measures over 100 volts on a DVM will have a true O/C trigger voltage of 330 to 350 volts; because that's the operating voltage of a Xenon tube, and those old trigger circuits were connected directly to the main capacitor via a 'safety' resistor. The implication is that e.g. Nikon's stated 250 volt withstanding hotshoe, is not safe with almost any pre-1990 flash. Basically, just round up any > 80v Botzilla readings to 350 volts, and you won't be far off. As for the 1000v trigger of the 'Colorsplash'. I have no idea why it would need such a high voltage, or why its designer would even consider using such a voltage, given the rarity and cost of components with a 1Kv rating. If anyone's interested I posted a thread on the subject of accurate trigger voltage measurement. Edited September 27, 2022 by rodeo_joe|1 Link to comment Share on other sites More sharing options...
JDMvW Posted September 27, 2022 Share Posted September 27, 2022 (edited) Ooops... In future, if ever, I'll post your thread link which I had forgot about. Basically, my own conclusion was, in any case, "don't use old 'strobes'" Edited September 27, 2022 by JDMvW Link to comment Share on other sites More sharing options...
John Seaman Posted September 27, 2022 Author Share Posted September 27, 2022 When I first checked, the voltage was actually higher than 1K, with the meter needle going off the scale. I wondered if there was some flaw in my method, but I think not (apart from the lowering of the voltage caused by the operating current of the meter). I guess the battery had weakened somewhat before I photographed the test for photo.net. Link to comment Share on other sites More sharing options...
hjoseph7 Posted September 27, 2022 Share Posted September 27, 2022 This little three colour flashgun came to me with a job lot of other stuff. It's unbranded but I later saw one on the auction site. It's a Lomography Colorsplash. I have a habit of checking trigger voltages and found that this gun, powered by a single AA battery, has a scary trigger voltage of nearly 1000V, by far the highest I've seen. And that's using a moving coil meter, heaven knows what the open circuit voltage is. So it's heading for the bin, but just in case you are tempted to use one of these on a digital camera, don't! Here it is, by the way the centre contact is negative on these. [ATTACH=full]1440359[/ATTACH] [ATTACH=full]1440360[/ATTACH] Wow that's a good way of checking the voltage ! I never tried it that way... Link to comment Share on other sites More sharing options...
John Seaman Posted September 28, 2022 Author Share Posted September 28, 2022 Wow that's a good way of checking the voltage ! I can't think of another way. Be aware that connecting a meter which draws even a miniscule current will reduce the voltage, as Rodeo Joe's link explains - at some length. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted September 29, 2022 Share Posted September 29, 2022 When I first checked, the voltage was actually higher than 1K, with the meter needle going off the scale. Just FWIW. Many of those 'old fashioned' moving-coil meters have an FS deflection current of only 50 uA, giving them a higher ohms-per-volt rating than a modern constant 10 Megohm input resistance DVM. On the 1000 volt range, a 50uA 'mechanical' meter will have a resistance of 20 Megohms, and hence give a more accurate reading (than a DVM) of a high-resistance source. I still can't figure out why anyone thought it necessary to have a constant 1KV or more floating around inside a tiny electronic flash gun. It might make a handy Taser in an emergency though. :eek: Link to comment Share on other sites More sharing options...
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