At 06:29 AM 7/20/2009, Jinx wrote: >I went out today and picked up a bagful of used disposable cameras > >It could be that the camera tube has an expected lifetime of something >a little over the 20 shots on the film. Or it may actually last much longer I've used dozens and dozens of those disposable camera flash units - haven't killed a tube yet. I was using 10uF 350V electrolytic caps with the tubes since what I needed was a repetitive strobe flash for signalling, not just a single but intense flash. So far as I know, all are still working after many years of relatively continuous use. As an aside, I've used the little DC-DC convertor circuit and that large (330uF 350V) cap to make blasting boxes for some of the local pyro guys. The existing transistor was too wussy for continuous use - I replaced it with a similar gain TO-220 device. The battery I use is a single "D" alkaline cell. They typically get at full year's use out of a single cell, using them several times per week. The guys seem to like them. They take longer to charge than the commercial blasting boxes that they use but quite frankly, that's never a problem. One neat thing is that I tapped off the voltage spike at the collector of the oscillator transistor and used that to make a bog simple loop resistance indicator consisting of 2 LEDs. One LED only lit: open circuit. The other LED only lit: short circuit. Both LEDs lit equally: about 100R loop resistance. Maximum loop test current never exceeds 10mA under any circumstance which is just fine for all pyro initiators that I am aware of. 100R loop resistance with >300Vdc is more than 3A firing current - quite acceptable. Maximum short circuit current is limited with a large (20W) 10R resistor so as to not completely fry the switch contacts when the output terminals are shorted. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist