Zener noise / oscillations

Robert Baer · 2012-07-23T08:16:24+00:00

Zeners all seem to behave: quiet, no oscillation IF run at or near the spec current (usually in the tens of mA). But, if one needs to run them at low currents (say 10uA to 500uA) then _watch_out_! Some brands at certain voltages are extremely noisy and subject to oscillation. The waveforms seen at low currents (2-50uA) look like randumb sawtooth generation, and as the current is increased the amplitude and probability increases (do NOT want to say "frequency" as that gives wrong impression). Then this "converts" to random noise. Eventually, there are "bursts" of NO noise. Then at higher current, noise bursts decrease in "frequency" and amplitude. That is what i see in general. However, i have found two zeners that, on a curve tracer, one sees little if any noise or spikes mentioned. NOW for the question: How can one test these particular zeners to ensure they do not or will not oscillate?* Yes, there are zeners made for low noise and those have a much lower spec current, BUT i cannot afford to have the factory dig the silicon mines, etc much less the high $$.

Jul 23, 2012 143 Replies

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Jan Panteltje 13 years ago

On a sunny day (Wed, 08 Aug 2012 14:09:08 -0400) it happened Spehro Pefhany wrote in :

Yes could have been that one, not sure. I did put on a better lens, I remember that.

Was a pretty decent enlarger. Gave it away together with cameras one day.

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Fred Abse 13 years ago

I had a Durst, can't remember the model number, for 35mm and 2 1/4" square, and a Japanese Astron for 5" x 4". Both with color filter drawers. I coveted a DeVere, too expensive.

(2 1/4" square is 6 x 6 cm, for Jan's benefit ;-) )

Most of what I did was 2 1/4" sq. (Mamiya C33, which had full double extension, same-size focusing.) Couldn't afford a Hasselblad.

For 5" x 4". I had an ancient Speed Graphic, and a British-made MPP Technical camera, with every-which-way motions, and triple extension. Macro was outstanding with that.

I'd *love* a large-format digital camera, and professional (dye sub?) printer.

Right now, I'm eyeing a Nikon, with a 24 x 36 mm. CCD, that'll take all the Nikon F lenses. Be still, my heart!

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

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Spehro Pefhany 13 years ago

Assuming you're talking about the D800, it has even dyed-in-the-wool Canonites talking about making a switch. Relatively reasonable price for a full-frame too.

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krw 13 years ago

Right. Color makes great snapshots but lousy art. B&W gives much better contrast and texture.

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