Author Topic: DE-5000 LCR meter strange behavior  (Read 2135 times)

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Offline alexoTopic starter

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DE-5000 LCR meter strange behavior
« on: February 27, 2017, 02:06:38 pm »
I measure 100nf ceramic disk caps with a DE-5000. It starts by showing a value of around 65nf and the value indicated keeps increasing over 90 seconds or so to around 85nf.

I wonder if anybody has some explanation. My other LCR metter is rock solid from the beginning.
 

Offline TimFox

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Re: DE-5000 LCR meter strange behavior
« Reply #1 on: February 27, 2017, 02:15:56 pm »
What type of ceramic part is this (X7R, Z5U, etc.)?
 

Offline alexoTopic starter

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Re: DE-5000 LCR meter strange behavior
« Reply #2 on: February 27, 2017, 02:55:23 pm »
No idea. I bought them on eBay - 1000 pieces. There is a small slip saying " Ceramic disk capacitors, 104PF, Tol +-80/20%, wvdc 50V and T.C. Y5V   

I tried with other ceramic caps as well and I saw the same behavior. Also, I tried diff frequencies for the meter.
 

Offline TimFox

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Re: DE-5000 LCR meter strange behavior
« Reply #3 on: February 27, 2017, 05:02:31 pm »
"Y5V" is the type of capacitor.  These are very non-linear, but I don't know why they would behave better on your other meter.
Can you try a film capacitor (polyester or polypropylene) of the same value on your suspect DE-5000?
 

Offline alexoTopic starter

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Re: DE-5000 LCR meter strange behavior
« Reply #4 on: February 27, 2017, 06:07:07 pm »
Doesn't do it at all with polystyrene caps. Rock solid. I tried quite a few values as I have about one cubic meter of those in various values , all 500V .

I really wonder what's going on here.
 

Offline Nermash

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Re: DE-5000 LCR meter strange behavior
« Reply #5 on: February 27, 2017, 06:25:28 pm »
My DE5000 does exactly the same thing with cheapo 100n ceramic caps.
« Last Edit: February 27, 2017, 06:40:57 pm by Nermash »
 
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Offline Conrad Hoffman

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Re: DE-5000 LCR meter strange behavior
« Reply #6 on: February 27, 2017, 07:53:14 pm »
You'd have to put a scope on it. Those high k ceramics can have huge temperature coefficients, but also surprising voltage coefficients. If the meter changes its excitation voltage for some reason, the indicated value will change. I also assume you don't have your warm fingers holding the cap?
 
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Offline alexoTopic starter

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Re: DE-5000 LCR meter strange behavior
« Reply #7 on: February 27, 2017, 08:05:18 pm »
I'm not touching the caps while being measured and I pick them up with tweezers. I also left one in like 30 minutes with the meter off to avoid exactly that sort of issue.

Beats me how these sort of caps can be usable for anything.

 

Offline Conrad Hoffman

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Re: DE-5000 LCR meter strange behavior
« Reply #8 on: February 28, 2017, 06:38:05 pm »
Anything? Well, they're useful for making a profit for the manufacturers! Very high k ceramics let you get a lot of capacitance in a small space, and sometimes keeping things small is the highest priority.
 
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