Re: Interupting xenon flash current ?

On Dec 5, 4:48 pm, Mike <nomtrxs...@xxxxxxxxxxx> wrote:
I believe there is a mistake with your measurement. In the common
cameras, the flash current is at the order of 100A and the duration is
~tens of milliseconds. They handle it with IGBT of SOT-223 form factor.

However there are the special pulse tubes for use with lasers, etc. They
have higher rate of the current increase and the shorter flash duration.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

That was my frst reaction also since I expected to see something less than 400A, but I can't find any reason
for such a major error.
I have a 200mv 200A shunt in series with the tube and am simply grabbing the voltage waveform across the shunt
with an HP 54502A storage scope. So with 1mv/A and reading 1.9v peak that's 1900A. I connected the 1V scope
calibrator output from an analog scope to 54502s input and it reads right on amplitude and time.

Mike
If there is no absolute truth then nothing can be known.

two possible sources of error
1) if the shunt is inductive it will read higher for the pulse

2) you may have a hugh common mode problem, i assume you have the
shunt in the low voltage returm path...anyway, try connecting both
ends of the scope probe to the same side of the shunt, i.e. you should
expect to see 0V pulse when you fire the strobe...and check if you
do...
you may need to use a differential probe or other special technique to
get an accuragte small signal measurment in the presense of the large
discharge pulse..

or use a larger value shunt...

Mark

.

Relevant Pages

  • Re: Interupting xenon flash current ?
    ... have higher rate of the current increase and the shorter flash duration. ... I have a 200mv 200A shunt in series with the tube and am simply grabbing the voltage waveform across the shunt ... Current shunt inductance can be a serious error in this time domain. ...
    (sci.electronics.design)
  • Re: Interupting xenon flash current ?
    ... have higher rate of the current increase and the shorter flash duration. ... I have a 200mv 200A shunt in series with the tube and am simply grabbing the voltage waveform across the shunt ... calibrator output from an analog scope to 54502s input and it reads right on amplitude and time. ...
    (sci.electronics.design)
  • Re: Interupting xenon flash current ?
    ... However there are the special pulse tubes for use with lasers, ... have higher rate of the current increase and the shorter flash duration. ... I have a 200mv 200A shunt in series with the tube and am simply grabbing the voltage waveform across the shunt ...
    (sci.electronics.design)
  • Re: Interupting xenon flash current ?
    ... shunt in the low voltage returm path...anyway, try connecting both ... expect to see 0V pulse when you fire the strobe...and check if you ... The scope gnd, the charge ...
    (sci.electronics.design)
  • Re: Interupting xenon flash current ?
    ... shunt in the low voltage returm path...anyway, ... expect to see 0V pulse when you fire the strobe...and check if you ... This is a very low inductance shunt. ... I connected the scope probe tip to the ...
    (sci.electronics.design)