Electronics > Metrology
More voltage references - die pictures
Noopy:
--- Quote from: Kleinstein on June 26, 2022, 03:58:21 pm ---The 1N825 I tested is a relatively new one from microchip and not symmetric - the other direction does not show conduction at 7.5 V. So this one is not symmetric. As much as one can see from the outside the construction looks similar: a silicon die with 2 rather thick shiny metal pads on both sides.
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I have a new 1N821 here... ;D
--- Quote from: mawyatt on June 26, 2022, 04:17:19 pm ---got a couple 1N34 Germanium diodes and connected them together in an attempt to create a Germanium PNP transistor ::) :-DD
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Sounds perfectly right! :-+ ;D
T3sl4co1l:
--- Quote from: Kleinstein on June 26, 2022, 03:58:21 pm ---How fast the transistor gain drops depends on the purity / carrier lifetime. With relatively pure material the diffusion length can be larger than 200 µm and carrier lifetime up to some 50 µs. For a zener diode I am afraid the substrate has relatively high doping level and this usually comes with a short carrier lifetime.
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Ah yeah, good point. Guess I wouldn't know if the doping is stronger on just the diffusions, but probably has to be both (them and substrate), eh?
--- Quote from: mawyatt on June 26, 2022, 04:17:19 pm ---Remember as a kid about 65 years ago when I started getting interesting in transistors and had started the beginning of a home lab with surplus stuff. After reading a bunch of books & articles about transistors, got a couple 1N34 Germanium diodes and connected them together in an attempt to create a Germanium PNP transistor ::) :-DD
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Such tiny things! I used a pair of 1N5404s, sadly they didn't work any better. ;D
I suppose it's....kinda dishonest, that those block diagrams are given like with ice cubes of N/P, without any mention of how they were "stacked" together, and why it has to be made in such a particular way as it does. And why it's not cubes to begin with, for very good reason. Well, oversimplifications being what they are...
Tim
floobydust:
Off topic - Crystal radio experimenters playing around adding an extra cat's whisker electrode to the galena (lead sulfide PbS) crystal, discovered transistor action.
Gyro:
This is what you're looking for guys... Complete with orignal article: https://www.eevblog.com/forum/projects/diodes-die-pictures/msg3870872/#msg3870872
Noopy:
You can find the Shanghai 17th Radio Factory 2DW234 here:
https://www.eevblog.com/forum/metrology/ultra-low-noise-reference-2dw232-2dw233-2dw23x/msg4417087/#msg4417087
https://www.richis-lab.de/REF23.htm
:-/O
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