D300 built-in flash, Part 1: Blinding speed

Started Dec 25, 2008 | Discussions thread
OP Marianne Oelund Veteran Member • Posts: 7,355
A few orders of magnitude away

Deejaybee wrote:

there is an alternative: are all connections properly terminated?
That sort of ringing can also be easily the result of impedance

Since the line is only about 3' long, ringing would be in the VHF range, and would require edge speeds on the order of 5ns or faster in order to excite it. The ringing captured is only around 500KHz - a few orders of magnitude lower - and is actual signal pickup from the flash circuitry.

But yes, even though there would be no visible effect on these waveforms, the line is terminated with 50ohms.

Just as a matter of interest are you using a photoreceiver
or bare diode?

It's a bare diode; not much gain is needed to detect light from a nearby flash.

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