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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th Jun 2018, 5:58 pm   #1
ColinTheAmpMan1
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Default Another strange component

Hi,
Some time ago I was given an enormous bag of assorted resistors. I recently managed to sort them out and now have a lot of useful resistors. There were two that puzzle me, though. They look like resistors, as can be seen from the attached photo, but the measured values and colour-code don't seem to make much sense to me. The colour-code is brown/green/gold/black or vice versa, but I can't see how a colour-code can sensible start with a black band. My bridge measures them to be 1R5, but my Chinese component-tester gives 0.4R. I have tentatively identified them as 1R5, 0.05%, but remain unconvinced. Neither my bridge nor my component-tester indicate any other properties such as inductance.
Any ideas?
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Old 10th Jun 2018, 6:14 pm   #2
G6Tanuki
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Default Re: Another strange component

There are plenty of low-value inductors that look like that.

See http://www.learnabout-electronics.or...nductors04.php
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Old 10th Jun 2018, 6:34 pm   #3
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Default Re: Another strange component

If it's an inductor then 0.5uH would be my guess:

http://coil32.net/online-calculators...alculator.html

EDIT: Whoops, I missed the colours you described, so yes, 1.5uH

Lawrence.

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Old 10th Jun 2018, 6:35 pm   #4
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Default Re: Another strange component

More likely to be an inductor, 1.5uH.
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Old 10th Jun 2018, 6:39 pm   #5
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Default Re: Another strange component

Hi!

It's a 1.5uH axial inductor about 1A d.c. current rating!

Colour-coded inductors code in micro-henries, e.g., brown-black-black = 10uH, brown-black-brown = 100uH, brown-black-red = 1mH and so on!

The clue that it's an inductor rather than a resistor is the wasp-waisted shape of the body - a resistor body is much more parallel-sided!

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Old 10th Jun 2018, 6:52 pm   #6
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Default Re: Another strange component

I would agree, looks like an inductor. I have seen these on bandoliers mixed with resistors for automatic assembly so maybe that's why you have a mix in your pack.
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Old 10th Jun 2018, 8:10 pm   #7
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Default Re: Another strange component

I read that code as 1, 5, divide by 10, give or take 1%, and it looks more like an inductor than a resistor, so a 1.5µH inductor would be my guess. A 1.5Ω resistor would not usually be so much fatter at the ends than in the middle.
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Old 11th Jun 2018, 2:07 pm   #8
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Default Re: Another strange component

To give the resistance perspective, the tables of similar inductors I use give the resistance of a 1.5UH inductor as around 0.2 to 0.3 Ohm.
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Old 11th Jun 2018, 5:24 pm   #9
ColinTheAmpMan1
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Default Re: Another strange component

Thanks, folks, for solving this. I have checked it on my Tek Type 130 and it measures at 1.5uH, as suggested. The oddity, though, is that my Marconi TF 2700 bridge has it at 5.6uH. The bridge is fine for resistance, so what could be the problem, do you think?
Colin.
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Old 11th Jun 2018, 5:37 pm   #10
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Default Re: Another strange component

I have got a Marconi TF1313A and it has a Q control that makes a lot of difference to the read value. It is very accurate once you get used to using it and would also get the correct value for that choke.
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Old 11th Jun 2018, 10:11 pm   #11
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Default Re: Another strange component

Hi

I tend to agree it's a 1.5uH inductor.
Normally 1.5uH would be Brown Green Gold usually with a Gold tolerance band also so the black band is a bit of a puzzler.

Regards
Symon
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Old 12th Jun 2018, 8:04 am   #12
Craig Sawyers
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Default Re: Another strange component

Quote:
Originally Posted by Refugee View Post
I have got a Marconi TF1313A and it has a Q control that makes a lot of difference to the read value. It is very accurate once you get used to using it and would also get the correct value for that choke.
Yes - me too. I have an HP automatic bridge, but my go-to instrument is my TF1313A. With a good old analogue instrument you (well, I) have a decent degree of confidence that it is telling the truth.

Craig
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Old 12th Jun 2018, 11:00 am   #13
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Default Re: Another strange component

It takes a little bit of learning to get confident with the TF1313A but once you are there your are sure.
It is indeed worth the bench space as anything modern would cost a fortune to get the accuracy of the TF1313A.
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