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dca55 questions

Started by nieradka, November 08, 2013, 11:21:05 PM

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nieradka

I just got a dca55, and was testing it out, and i have questions about its accuracy.

First off its showing all of my diodes with .05 to .1v higher voltage drop than my DMM. My DMM seems to be giving more consensus readings, eg oa126s around .6v where the dca55 reads .75v, or most germaniums around .25 on the dmm, and .33 on the dca55.

Second, i tested a batch of germanium transistors on brought on a whim  some months back, and they are all showing a leakage of 0.00 ma. The hfes seem reasonable (75, 70, 110, 67, 75, 69, 69, 81, 83, 80, 83, 89, 70, 85, 61, 69, 82, 86, 62, 60.) Now, i know they are IT308v s and i know they are low leakage, but all being 0 leakage is suspicious. And if that is legit, what can you recommend i can build with them. The only germanium transistor projects ive built are percolators and screwdrivers, and these seem appropriate for neither.

Thanks--

nieradka

Well i see jons post from a few topics down. So if the readings are legit, Rangemasters, and maybe a tonebender or buzzaround?

culturejam

I noticed the same thing with the diode readings. Somebody on FSB explained it, but I didn't understand it exactly.

As for the leakage, anything below X amount will be listed as 0. It seems to read leakage as "ranges" rather than absolute values. I think the software rounds leakage to fit into a specified set of ranges.

Also of note: anything that measures a forward voltage drop of greater than 0.39V will be classified as "silicon". This holds true for transistors as well (B>E voltage drop reading).
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nieradka

Thanks, so it looks like its operating as it should. The diode thing, is probably not a problem, for what i am mostly doing the absolute number doesnt matter, just relative to other diodes i have.   

culturejam

Here's a post about leakage in the Atlas that will bake your noodle:
http://www.diystompboxes.com/smfforum/index.php?topic=74492.0

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jimijam

a lot of russian ge transistors have shunts in them that make them look to have no leakage
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