Author Topic: K71-7 precision capacitor  (Read 1794 times)

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Offline shodan@micron

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K71-7 precision capacitor
« on: June 11, 2021, 08:58:29 pm »
void
« Last Edit: July 14, 2021, 05:13:16 pm by shodan@micron »
My lab in Instagram. LXI Instruments Data Logger apps.
I'm need tank of Bose-Einstein condensate....
 
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Offline bsw_m

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Re: K71-7 high precision capacitor
« Reply #1 on: June 11, 2021, 11:18:14 pm »
In fact, these capacitors actually have very good accuracy and low Df and Da.
I am sorry, I could not find my data on the measurement of dielectric absorption (it was a long time ago). But I remember exactly that the dielectric absorption of these capacitors was low. Measuring again is a lengthy process and requires preparation. But I measured the capacitance and Df. I measured 2 randomly taken samples with a nominal value of 470nF 5% tolerance  and 100nF 0.5% tolerance. Measurement frequency was 1000Hz.
« Last Edit: June 11, 2021, 11:20:40 pm by bsw_m »
 
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Online bob91343

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Re: K71-7 high precision capacitor
« Reply #2 on: June 12, 2021, 02:19:27 am »
I don't consider 0.5% tolerance high precision.  But it's a relative term.  I think these could be considered general purpose, although they are better than most.
 

Online bob91343

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Re: K71-7 high precision capacitor
« Reply #3 on: June 12, 2021, 03:00:11 am »
You can't fight over opinions.  Since precision is a general term, each of us interprets it differently.  I think 0.1% is precision.  Those would be expensive lab standards but I think that gets into the realm of precision.
 

Online bdunham7

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A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online bob91343

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Re: K71-7 high precision capacitor
« Reply #5 on: June 12, 2021, 03:56:15 am »
Yes that is a precision capacitor.
 

Online ramon

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Re: K71-7 precision capacitor
« Reply #6 on: June 12, 2021, 04:05:44 am »
Do they keep their properties after soldering?
 

Offline bsw_m

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Re: K71-7 precision capacitor
« Reply #7 on: June 13, 2021, 08:06:58 am »
I have finished testing the leakage current of the K71-7 470nF 250V capacitor at nominal voltage.
Voltage source: lab power supply B5-50
Current metter: V7-49 electrometer.
Series resistor ~ 10GΩ KVM.
Test time ~ 9.5 h.
Leakage current is about 8pA.
Possibly, the leak current can be even lower, but 10GOm resistor too small in order to get rid of the noise rise in the lower measuring range.
I am attaching a raw data file.
« Last Edit: June 13, 2021, 08:11:46 am by bsw_m »
 

Offline Kleinstein

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Re: K71-7 precision capacitor
« Reply #8 on: June 13, 2021, 02:22:26 pm »
When testing the leakage current directly, there is not just the noise of the ampmeter, but also noise if the voltage source to power the capacitor. Chances are the 250 V source is more noisy than the electrometer input votlage.
The other part that is seen is the dielectric absorbtion of the capacitor - that is likely much of the initial decay part.
 

Offline dzseki

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Re: K71-7 precision capacitor
« Reply #9 on: June 13, 2021, 09:08:10 pm »
I don't have these for sale anymore but you might find it interesting afterall:
https://www.eevblog.com/forum/buysellwanted/wts-precision-capacitors-109nf-125v-0-25/msg1880765/#msg1880765

Some more measurements:
https://drive.google.com/drive/mobile/folders/1eVK5zdJ4sEdfRsW1ztHgo94Y7h8NaYLF?usp=drive_open

I've of course have kept a few for future use...
« Last Edit: June 13, 2021, 09:14:37 pm by dzseki »
HP 1720A scope with HP 1120A probe, EMG 12563 pulse generator, EMG 1257 function generator, MEV TR-1660C bench multimeter
 
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Offline Russ3000

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Re: K71-7 precision capacitor
« Reply #10 on: June 13, 2021, 10:23:59 pm »
Used similar 0.49175 uF capacitors in a tube RIIA preamplifier with very good sound.
 

Offline Henrik_V

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Re: K71-7 high precision capacitor
« Reply #11 on: June 18, 2021, 07:30:18 am »
Okay! lets fight!!! :box:
Try show to me any other caps with 500nF capacitance and tolerance better 0.5%.  ;D ;D ;D
Vishay say, 1...2% its precision capacitor, but i don't see better 1% caps.
A short look into my collection
Jahre makes them  .. or has made them

https://www.jahre.de/en/products/mica-capacitors/small-capacitors/

actual offer is 0.5% , but that's just a question of $$ if you ask them ;)
« Last Edit: June 18, 2021, 07:45:32 am by Henrik_V »
Greetings from Germany
Henrik

The number you have dialed is imaginary, please turn your phone 90° and dial again!
 
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Offline Henrik_V

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Re: K71-7 precision capacitor
« Reply #12 on: June 18, 2021, 08:38:04 am »
here is the a bigger one  :-DD
« Last Edit: June 18, 2021, 08:40:35 am by Henrik_V »
Greetings from Germany
Henrik

The number you have dialed is imaginary, please turn your phone 90° and dial again!
 
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