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Author Topic: What are these diodes?  (Read 1696 times)
KG6Q
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« on: May 13, 2012, 12:06:04 PM »

I have come across a bag of diodes that all appear the same (size, color with clear anode and cathode markings) but with two different part numbers:

ST 3R 22
and
1149 212 7329

They all look like discrete power rectifiers. My research to identify these diodes and get specs on them has yielded zero.

Does anyone know anything about these diodes or can point to a good cross-reference website?
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W0BTU
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« Reply #1 on: May 13, 2012, 12:23:29 PM »

ST is probably the manufacturer, and 3R22 is likely the P/N. The other numbers probably are the date of manufacture and other stuff important only to the maker.

http://www.google.com/#hl=en&newwindow=1&sclient=psy-ab&q=%223r22%22+diode&oq=%223r22%22+diode

Looking at only the Google search results, it looks like a 22 volt Zener to me.

UPDATE: Here you go: http://www.americanmicrosemi.com/information/spec/?ss_pn=3R22,A,B

22 volt 3 watt Zener. You can easily verify that with a pot, a power supply, and a DVM. I'd also use a limiting resistor in series with the pot.
« Last Edit: May 13, 2012, 12:29:53 PM by W0BTU » Logged

KG6Q
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« Reply #2 on: May 14, 2012, 08:50:59 AM »

Thanks, I'll run a Zener confirmation check on the ST 3R 22 diodes.


The other 'diodes' in the bag are identical in size and anode/cathode markings as the 3R 22's. Those have no hint of a manufacturer and have different P/N markings:

1149 212 7329

Any hint of what these 1149 212 7329's might be?

Lacking any info on the 1149 212 7329's , I'll do a Zener check on these when I check the 3R 22s.
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W0BTU
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« Reply #3 on: May 14, 2012, 10:02:44 AM »

Any hint of what these 1149 212 7329's might be?

I don't. I didn't bother to search on that, because I just assumed I wouldn't find anything.

You could probably dispense with a pot like I suggested. Just calculate the value of a series resistor that won't pass too much current, etc. even if you short the diode.

Please let us know what you find. I never heard of a diode P/N that started with the number 3, and even though we found that web page, there's not a 100% guarantee that's your diodes.

Do you have a power supply > 25 VDC that you can use for this test?
« Last Edit: May 14, 2012, 10:05:37 AM by W0BTU » Logged

W9GB
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« Reply #4 on: May 14, 2012, 11:43:52 AM »

"R" is often used with Zener diode part numbers to note reversal of traditional Anode / Cathode.
That would be useful for a NEGATIVE bias, such as - 22 VDC.
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W0BTU
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« Reply #5 on: May 14, 2012, 11:58:03 AM »

Yes, I have some here, Greg. They are 1N1357RA. And they are stud mount, 10 watt or something. Ever see a 3 watt stud-mount Zener? (I haven't.)

He did say "discrete power rectifiers". I should have caught that. I assumed they were axial lead diodes.
« Last Edit: May 14, 2012, 12:00:51 PM by W0BTU » Logged

WB2WIK
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Posts: 20634




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« Reply #6 on: May 14, 2012, 02:06:08 PM »

I have come across a bag of diodes that all appear the same (size, color with clear anode and cathode markings) but with two different part numbers:

ST 3R 22
and
1149 212 7329

They all look like discrete power rectifiers. My research to identify these diodes and get specs on them has yielded zero.

Does anyone know anything about these diodes or can point to a good cross-reference website?

The 1149 212 7329 are lot and date code numbers which have nothing to do with device ratings or description.

The 3R22 is a low power 22V 20% tolerance zener diode rated Vz = 22V @ Iz = 35mA.

It's a low current device made by Solitron Devices.

Data sheet is available: http://www.datasheetarchive.com/3R22-datasheet.html#datasheets
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WB2WIK
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« Reply #7 on: May 14, 2012, 02:07:53 PM »

Thanks, I'll run a Zener confirmation check on the ST 3R 22 diodes.


The other 'diodes' in the bag are identical in size and anode/cathode markings as the 3R 22's. Those have no hint of a manufacturer and have different P/N markings:

1149 212 7329

Any hint of what these 1149 212 7329's might be?

Lacking any info on the 1149 212 7329's , I'll do a Zener check on these when I check the 3R 22s.

Again, those long numeric strings are lot code and date code, and not device description.  7329 = 29th week of 1973, when they were manufactured.

There is a vendor identification, though.  ST = Solitron Devices.  ST was their registered trademark way back when.
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KG6Q
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« Reply #8 on: May 15, 2012, 09:22:45 AM »

I still haven't got around to Zener voltage checks, but I will soon.

To further clarify, these devices (1149 212 7329 and ST 3R 22) both have axial leads.

I agree the "1149 212 7329" is likely a lot/date code, but that is the ONLY marking on those parts.

My suspicion is that - since both types were in the same bag - it's likely they are all the same part but with two different markings. The Zener test should give a strong hint.
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KG6Q
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« Reply #9 on: May 15, 2012, 05:22:50 PM »

OK, I did a Zener test on both 1149 212 7329 and ST 3R 22 diodes. Here are the results:

ST 3R 22 does appear to be a 22V (nominal) Zener diode. The diode 'Zenered' at about 22.5V and maxed out about 24.8V with a maximum supply voltage of 45V. I used a 100 ohm resistor in series with the Zener and variable voltage supply. Conclusion: it looks like a 22V 20% Zener diode as Michael suggested.

1149 212 7329 appears to be some kind of rectifier diode unless it 'Zeners' somewhere greater than 45V. Up to that voltage, I saw no Zener break. The forward voltage maxed out about 1.2V suggesting some kind of HV power supply rectifier. Conclusion: who knows  Undecided
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N4CR
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« Reply #10 on: May 15, 2012, 07:29:25 PM »

With a current limited high enough voltage you could find it's avalanche voltage. That would at least tell you it's max reverse voltage in a non-destructive way. With destructive testing, you could determine it's current capacity. You can check it's forward voltage drop to determine a bit more about it. It's difficult to get much more out of an unmarked diode.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
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