Re: Filter/Speed/Meter & DON'T meter using a Nikon Camera

["phillip geller" <filje@xxxxxxxxxxx>]

bob ,

>
> >BTW I bought some eg&g photo cells a couple of years ago
> >and they all have green/blue glass filters over the sbc.
>
> Without knowing what they were intended for, it's hard to know whether the
> coating was to block IR or merely protect the cell.


pretty sure it's a blocker. Otherwise it would be clear like the sensor in
the early sbc hand held sekonic meter I used to use. The sensor was a plain
blue photo cell. The EG&G one looks just like the one in a minolta meter.


> Ah, they aren't operated like flash tubes. Flash tubes are connected to a
> source of high voltage on a capacitor. When it's time to flash, there's a
> second system to start the ionization in the flash tube, which then allows
> the capacitor to discharge through the tube. I'm not sure how variable
> intensity flash circuits work, since the discharge isn't to empty the
> capacitor, but is regulated by some other circuit.

In some cases a scr is used to stop the flow of electricity to the flash
tube.
Some studio flash units do this now. In other cases banks of capacitors
are switched in and out of the circuit in parallel. In other cases
the capacitors are  only allowed to charge to a certain voltage.





> LEDs in remotes are driven by integrated circuits at relatively low
> voltages, and don't depend on capacitive discharges. But the key you hold
> down determines the exact pulse pattern for the function the key
represents.



yeah but they sure are a lot brighter than when you just hook a battery up
to  the
leds at therated voltage.


plug a photocell into the audio - in jack of an amp and enjoy :)

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