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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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20th Apr 2019, 10:44 pm | #1 |
Heptode
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Capacitors values
I have some capacitors with values I don't understand , 102 , 104 , 223 , 474, etc.
Does anyone know how to convert to pf , nf or mfd ? Robin |
20th Apr 2019, 10:51 pm | #2 |
Heptode
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Re: capacitors values
The first two digits are the value, the last digit is the number of zeros giving the capacitance in pF. eg 104 is 100000pF or 0.1uF
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21st Apr 2019, 6:46 am | #3 |
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Re: capacitors values
A 1u or 1 micro farad cap is 0.000,001, a 1p or 1 picofarad is 0.000,000,000,001, as Martin says the last digit = how many zero's is after the value, but if you write out 100n as 10/0,000, 10n as 10,/000 1n as 1,/000 etc, etc light dawns . It can get mindbending as 1n is 1000p and some folk don't use nano, especially older schematic's and some suppliers search engines. Some caps are marked mmf, which is micro, micro farads, easier if all caps (or any components come to that) came with a big label with big clear print on like the bottles Alice had : )
Andy. Andy.
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21st Apr 2019, 6:18 pm | #4 |
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Re: capacitors values
Just read them as if they were colour codes on resistors with pf as a base unit.
103 = brown black orange = 10k = 10kpf = 10nf = 0.01uf Before standardisation, sometimes k or kpf was indeed used in schematics in stead of nf. |
21st Apr 2019, 6:30 pm | #5 |
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Re: capacitors values
What was the aversion to "nano" all about?
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21st Apr 2019, 6:33 pm | #6 |
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Re: capacitors values
How to bring in another step of confusion! As explained, the basic meaning is adequate and easy to understand. No need to complicate matters IMO.
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21st Apr 2019, 8:51 pm | #7 |
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Re: Capacitors values
Be careful with 'mfd'. It could be that the person meant 'uF' (microfarad) or 'mF' (millifarad), although the former is more likely.
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21st Apr 2019, 9:06 pm | #8 |
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Re: Capacitors values
Yes it can be very confusing: equally, in the 1930s/early-1940s it was quite common to come across US circuit-diagrams where "M" was used to indicate Kilohms. I've got an official RCA schematic for the AR88 which has grid-resistors labelled as "330M" which at first glance makes no sense, until you look further and find a potentiometer labelled "2MEG" and so get to retune your powers-of-ten-sense.
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21st Apr 2019, 11:07 pm | #9 |
Heptode
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Re: Capacitors values
Thanks for all your help guys.
Robin |
22nd Apr 2019, 12:29 am | #10 |
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Re: capacitors values
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22nd Apr 2019, 12:32 am | #11 | |
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Re: capacitors values
Quote:
Last edited by Maarten; 22nd Apr 2019 at 12:38 am. |
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22nd Apr 2019, 1:42 am | #12 |
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Re: Capacitors values
Perhaps this read is OK? from Homo Ludens website:
Q: Your schematic so-and-so shows a capacitor having a value of 33n. I've never in my life seen anything like that. I only know uF and pF as units for capacitance. Is the n a typo? A: You surely live in the USA, where nF (or just plain n, when it's obvious that it refers to a capacitance value) strangely is seldom used. Instead it is widely used all over the rest of the world. The basic unit of capacitance is the Farad, its symbol being F. This basic unit can be used together with any of the prefixes of the International System of Units, such as m for milli, u (or more correctly the Greek letter mu) for micro, n for nano, or p for pico. So, 1F = 1,000mF = 1,000,000uF = 1,000,000,000nF = 1,000,000,000,000pF. And in a schematic, often the F isn't printed because it's obvious, so you will see capacitances specified in p, n, u, or sometimes even m. To an excellent website :https://ludens.cl/index.html Joe |
22nd Apr 2019, 8:59 am | #13 |
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Re: Capacitors values
What was BS1852 brought in using the unit as a decimal point for values exceeding 1 unit.
e.g. 2.2k = 2k2, and for capacitors 2.2n = 2n2. It is possible to see n47 = 470p, but less common. One magazine adopted 0u1 (= 100nF = 0.1uF) but no manufacturer used this. The numerical system on inductors relates to 1uH, so 103 = 10,000uH = 10mH. |