> I've used dozens and dozens of those disposable camera flash
> units - haven't killed a tube yet.  I was using 10uF 350V caps 

Things progressing nicely with the project and initial tests look
promising. Hopefully should be able to share soon

Couple of questions -

----------

Are there any particular parameters to look for when selecting
the storage capacitor ? For example series resistance. The flash
tube draws a lot of current for a short time and I worry that this
is like the screwdriver method of discharging a capacitor, which
I believe is not good for it

-----------

I'd like to have the capacitor selectable for different flash rates
and different brightnesses. For instance select between 22uF, 100uF
and 220uF. Refering to Figure 3

http://www.rory.co.nz/projects/lighting/beat_strobe.php

I have some toggle switches rated at  250V 3A / 125V 3A. As
they're DPDT, the contacts can be paralleled for twice the current

Do you think a switch between capacitor -ve and the 0V rail will
be OK ? The author of the page above calculates that the current
through the tube is of the order of > 500A/cm^2, and I reckon the
duration is around 25us for 22uF and 100us for 250uF

What I'm not sure of though is the current in the -ve rail, ie whether
amperage seen in the tube would also be apparent through the switch.
The static voltage across the switch will near 0 when idle, going by
the datasheet resistance of 10 milliohms

If it might take out the switch then perhaps a power FET between
the -ve of each capacitor and the 0V line. The FET gates can be
controlled with a low-power rotary switch to the gates. The cost
would probably be similar compared with a toggle switch as above

TIA

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