Re: Function of component in flash tube trigger circuit?
- From: "Ian French" <ianf@xxxxxxxxxxxxx>
- Date: Mon, 28 Apr 2008 19:33:02 +0100
"N_Cook" <diverse@xxxxxxxxx> wrote in message
news:fv49ki$qlj$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
http://home.graffiti.net/diverse:graffiti.net/sf2.jpg
No markings, a black potted box 7x7x 15mm external dimensions.
If a stepup transformer , why so small?
0.3 ohms between blue and red lead and 144 ohms between blue and brown
lead
which goes directly to the trigger filament around the flash tube.
Red goes to ground and blue wire goes via 0.2uF, 250V capacitor to the SCR
cathode. 22mH and 20uH inductance
What is the problem, this is just a standard trigger transformer.
Normally the capacitor is charged up to 150V to 250V and then when the SCR
is turned on the 150V to 250V is applied across the primary of the
tranformer. The transformer steps up the voltage ( turns ratio about 20:1)
and generates a trigger voltage of 3 to 5 kV. This ionises the gas inside
the flash tube, and the resistance (impedance ?) is reduced sufficiently for
the 150V to 250V to strike across the tube.
The transformer is small because it only handles the tiny power to initiate
the flash in the first place. It does not handle the 50 J or whatever that
goes through the tube.
Ian.
.
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- Function of component in flash tube trigger circuit?
- From: N_Cook
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