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Capacitor Identification

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fordo

New Member
I have a small ceramic or tantalum capacitor. On one side it is marked:

102
AMJ

On the other side it is marked:

103
E1M

Any idea what these codes mean? They don't seem to match any of the coding schemes I've found so far. Thanks.
 

Mike_2545

Super Moderator
Multiplier used on Capacitor Marking Code
Third Figure Multiplier
0- 1
1- 10
2- 100
3- 1000
4- 10 000
5- 100 000

You have a 102 and 103 marking, maybe someone can make heads or tails of the AMJ & E1M
 
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Sceadwian

Banned
Are you sure it's not just a printing mishap like the ink wasn't fully applied to the 2 side? Take a look at them under magnification, or post images if you're able. Please for the love of my sanity if you are able to post images, make sure they're fully in focus. 9 out of 10 images I see posted here are badly out of focus in the subject areas field of view.
 

fordo

New Member
The cap(s) is pretty small, about 1/8" x 3/16" radial leaded. I actually put the cap(s) under a low power microscope and there is no doubt about the codes. I know this is puzzling because of the "102" on one side and the "103" on the other side. Also, to further confuse things I haven't been able to locate any info on the E1M or AMJ codes. Finally, I have a tape strip of about 20 of these caps and read the same info on all of the ones I looked at under the microscope (about 5 at random).

If I had a capacitance meter (are inexpensive meters able to read small values like these probably are accurately?), I would probably be able to determine whether they are 0.01µF or 0.001µF and just chalk off the rest of the codes as one of those things I'll never know.

I guess I was hoping someone may have run across a code list that I haven't.

Thanks again.
 

mneary

New Member
You can test with a (low voltage) source of 60Hz, and a reasonably high impedance meter. Let's assume you're only distinguishing between 0.01µF and 0.001µF, and don't need an accurate measurement.

At 60 Hz, 0.01µF has a reactance of 265kΩ. If you place it in series with a 220kΩ resistor, the two will have a similar voltage drop. (Total won't equal the input voltage; the capacitor is reactive, not resistive.)

If it's 0.001µF, the voltage across the resistor will be about 1/10 of the test voltage.
 
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