Capacitors for Flash guns.
Tareq Hoque
>they age.
>Does anyone have any suggestions or sources, in the UK ideally or mail order
>internationally otherwise, of the sort of large
>capacitors I need ? ideally something like 220yF 450V.
>
>Many thanks,
>
>Simon Monk. s...@uk.ac.lancs.comp
Mouser Electronics and All Electronics both sell Photoflash capacitors
by mail order. They both have 800 numbers which I don't know off
hand.
=tareq
Simon Monk
for a 100 Joule sort of energy. Flash tubes are OK, I can't find any
larger than 25 J, but I can use more than one, and this may be benefical
in my design, by allowing firing in rapid sucesion for fast strobe effects.
However I can't find a source of high capacity high voltage capacitors.
RS has nothing much, the best I could find was 47yF 400V (if memory serves
me correctly) from Maplins. I calculate that for an erergy of 100 J, I need
1250yF at 400V. Which would require about 24 of the Maplins caps. I had a
look inside a flash gun of mine and found a 470yF 400V cap, so obviously
these things exist. I am reluctent to go out buying old flash guns to
rob them of their capacitors, especially as they tend to loose capacity as
Barry Ornitz
>for a 100 Joule sort of energy. Flash tubes are OK, I can't find any
>However I can't find a source of high capacity high voltage capacitors.
What you need are energy discharge capacitors. These are high voltage units
designed for discharge service having minimal internal inductance. They work
well with the high energy tubes designed for this service. For example, one
unit I have is rated at 16 uF, 5 KV peak. It has 0.12 uH internal inductance.
It will store 100 J at a voltage of 3.54 KV.
You might look for military surplus flash tubes used for aerial photography.
Edgerton's books and articles on strobes should give lots of details on
these systems.
I bought a 250 J tube a few years ago at a hamfest for $2. I also have an 18 uF
10 KV discharge capacitor with 0.04 uH series inductance to drive it. This
capacitor was designed for laser flash-tube driving at high duty cycles. It
weighs about 50 pounds! I don't want to be around when this tube fires.
Barry
-----------------
| ___ ________ | Dr. Barry L. Ornitz WA4VZQ
| | / / | | Eastman Kodak Company
| | / / | | Eastman Chemical Company Research Laboratories
| |< < K O D A K| | Process Instrumentation Research Laboratory
| | \ \ | | P. O. Box 1972, Building 167B
| |__\ \________| | Kingsport, TN 37662 615/229-4904
| | INTERNET: orn...@kodak.com
-----------------
Tareq Hoque
>In article <1992May11.1...@comp.lancs.ac.uk> s...@comp.lancs.ac.uk
>(Simon Monk) writes:
>I'm in the process of designing a studio flash for my own use. I'm aiming
>for a 100 Joule sort of energy. Flash tubes are OK, I can't find any
>larger than 25 J,...
>However I can't find a source of high capacity high voltage capacitors.
All Electronics is selling new 210uF/330V Photoflash Cap for $1.25ea.
Cat # PPC-210
All Electronics
P.o. Box 567
Van Nuys, Ca 91408
1-818-904-0524
1-800-826-5432
The also have several other high voltage caps available.
=tareq
Geoff Swan
> I'm in the process of designing a studio flash for my own use. I'm aiming
> for a 100 Joule sort of energy. Flash tubes are OK, I can't find any
> larger than 25 J, but I can use more than one, and this may be benefical
> in my design, by allowing firing in rapid sucesion for fast strobe effects.
Normally studio flashes are at least 2000J.
> However I can't find a source of high capacity high voltage capacitors.
> RS has nothing much, the best I could find was 47yF 400V (if memory serves
> me correctly) from Maplins. I calculate that for an erergy of 100 J, I need
> 1250yF at 400V. Which would require about 24 of the Maplins caps. I had a
Try raising the voltage on the caps. Remember the energy in them is
proportional to the square of the voltage and only linearly related to
capacitance. So doubling the voltage gives you four times as much energy.
I built a studio flash unit by using a switch mode off-line supply (240VAC
to 2kV) feeding a capacitor bank and varying the voltage to it to control
the output power. This is not a project for beginners - one slip of the
screwdriver and you'll lose your arm.
> Simon Monk. s...@uk.ac.lancs.comp
Sla/n go fo/ill,
Risky B.
--------------------------------------------------------------------------
Geoff Swan _--_|\ swa...@megadata.oz.au
Megadata Pty Ltd / \
2/37 Waterloo Rd, North Ryde, \_.--._/ +61-2-805-0899
NSW 2113, Australia. v (AH) +61-2-477-6519
Simon Monk
>In article <1992May11.1...@comp.lancs.ac.uk>, s...@comp.lancs.ac.uk (Simon Monk) writes:
>> I'm in the process of designing a studio flash for my own use. I'm aiming
>> for a 100 Joule sort of energy. Flash tubes are OK, I can't find any
>> larger than 25 J, but I can use more than one, and this may be benefical
>> in my design, by allowing firing in rapid sucesion for fast strobe effects.
>
>Normally studio flashes are at least 2000J.
>the output power. This is not a project for beginners - one slip of the
>screwdriver and you'll lose your arm.
>
100 or perhaps 200 J. This is infact more than many budget amateur studio
flashes give out, and 2 or 3 times more than a camer top flash gun and makes
the design much easier for one of my limited abilities.
Many thanks for all the advice and sources to those who I didnt get round
to replying to personally. I'm waiting to receieve a catalog from
Newark electronics, Unit 4, Daux Rd, Billinghurst, west sussex. I've lost the
phone number I'm afaraid. Butb they seem like the best bet.
Simon Monk.
William
LESS powerful...
So I have a dozen or so of these one-inch flash units used in
cheap cameras, with 200 uF 300V or so capacitors...
How small a capacitor can I make that and still get it to flash?
Or, how much can I lower the voltage?
Thanks
BillW
Bob Myers
> >toxic. Any one have more detailed info about this?
> >
> >Behnam Sadeghi
>
> Older capacitors, as well as many transmission line transformers still in
> use, have PCB oil in them. When I was a kid, my brother and I unwound an
> old cap from a fighter jet, so I guess we're poisoned.
>
> I belive PCB oil has been banned from such use for many years.
Older *OIL* capacitors may have PCBs in 'em.
In aluminum electrolytics, the electrolyte is usually just ethylene glycol
(antifreeze), with traces of "other stuff" to make it conductive (note that
it's not the fluid/paper layer that is the dielectric in electrolytics, it's
the oxide layer that's "grown" on the foil; the fact that this layer is so
thin is what gives these caps their high C per unit volume). Unfortunately,
I'm not sure what the added "stuff" is - but I doubt that there's a significant
health hazard here (unless you tend to blow these things up on a very regular
basis! :-)).
Bob Myers KC0EW Hewlett-Packard Co. |Opinions expressed here are not
User Interface Tech. Div.|those of my employer or any other
my...@fc.hp.com Fort Collins, Colorado |sentient life-form on this planet.