There is a tiny neon indicator in my disposable camera that flashes when the camera is ready to take a picture. Does the neon indicator limit the maximum voltage the photoflash capacitor can be charged? I connected 2 AA batteries in series instead of the one it normally uses but it didn't increase the amount of voltage the cap was charged to by a significan amount. I was expecting 250-300 volts instead of the normal 150 volts. I got about 175 volts but I had to let it charge for quite a while to get that. It did charge up much faster though.
The cheap cameras found by the boxload at the thrift stores will almost always have a charge cap rated at 330 volts. I find that you will end up around 330 volts no matter how long you wait.
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Has a basic schematic that shows how the neon indicator works. It won't affect the max charge. The "rectifier diode" will prevent the neon lamp from draining the charge after you turn off the circuit. Sometimes the neon indicator is on the other side of the diode. In that case if you turn off the charge circuit then the neon lamp will drain the charge down to around 80 volts until the lamp goes out.
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Has done about anything you can to these xenon flash circuits. Especially, read his safety link
Maybe the capacitor has not been used in years, and has gotten a voltage-dependent leakage as a result. Aluminum electrolytic capacitors are known to do that.
Often, they can be restored by exercising them. Apply charge to the cap for several minutes, maybe half an hour. Maybe also discharge it every couple or few minutes while doing this - preferably with the xenon flashtube if it will work at the reduced voltage.
Also, be sure that your 1.5V AA cell is in good condition! There is one 1-AA camera flash board that I tried with higher voltages, with not-so-good results. At 2V, parts get uncomfortably hot and degrade in operformance and produce a bit of smoky-burning odor. At 2.3V, it failed with smoke production in mere seconds.
Another possibility, slight chance: Could your meter be loading down the output? I like think that you need an unusually weak battery or an unusually low impedance meter (or both) for that to happen, but there is a test... Let the board run unmetered for 15 seconds after its output voltage levels off, then put the meter back on. Is the voltage at that time higher and decreasing towards the lower 175V one?
Now, yet another thing: I have known one 1-AA camera flash board to have a neon lamp that does some regulating. Once the main capacitor voltage reaches somewhere around 280 volts, the neon lamp turns on, and adds significant loading to the capacitor. The neon lamp appears to me to not achieve complete regulation; what I saw was partial regulation. Also, that neon lamp had unusually high voltage across it while it was glowing - around 260 volts IIRC. I suspect the neon was mixed with some gas other than a "noble gas" to achieve that. This 1-AA camera flash board was from Kodak "Max" cameras. I have seen 2 versions of this board with minor differences between them. However, I am *disclaiming* that *all versions* of the 1-AA flash board with high rate of usage in Kodak "Max" cameras have this oddball-higher-voltage neon lamp.
Yeah I was thinking too that the neon tube was regulating. Never the less, when I connected the output of the flash unit to a trigger transformer that I plan on using for my dye laser, I get a nice fat spark and that's with just one battery powering the flash unit. The input for the trigger transformer is 240 volts so I figure the flash unit must be producing pretty close to that. BTW the flash unit is out of a small walgreen brand disposable camer. Its a tiny thing too.
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