On Wed, 26 Jun 2002, Olin Lathrop wrote:

>> Or even better glue a thermistor to the resistor and run the flash until
>> the readout (ohms) is stable. Then disconnect the flash supply and connect
>> a benchtop PSU across the R and set it until you obtain the exact same
>> reading. ...
>
>This will only measure the RMS current going into the flash, which will NOT
>tell you the power going into the flash.

Unless the supply voltage is known and constant. Which it is in the lab,
usually. I have used the method, detailed above by me, for flashes, pulsed
semiconductor lasers, pulse welders, and radio transmitters, to get real
Pin in rustical conditions. Subsequent checks with a RMS power meter were
within 2% usually. You must realise I've been into this kind of thing for
some time now ;-).

Imho, there are two ways to get real world workable data about the
equipment you are studying: one with, and ten without $10k worth of
measuring equipment <g>.

Peter

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