Capacitors values - UK Vintage Radio Repair and Restoration Discussion Forum

line sync · 20th Apr 2019, 10:44 pm

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

sortedradio · 20th Apr 2019, 10:51 pm

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

Diabolical Artificer · 21st Apr 2019, 6:46 am

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.

Maarten · 21st Apr 2019, 6:18 pm

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.

julie_m · 21st Apr 2019, 6:30 pm

What was the aversion to "nano" all about?

stevehertz · 21st Apr 2019, 6:33 pm

Quote:

Originally Posted by Maarten

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.

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.

G8HQP Dave · 21st Apr 2019, 8:51 pm

Be careful with 'mfd'. It could be that the person meant 'uF' (microfarad) or 'mF' (millifarad), although the former is more likely.

G6Tanuki · 21st Apr 2019, 9:06 pm

Quote:

Originally Posted by G8HQP Dave

Be careful with 'mfd'. It could be that the person meant 'uF' (microfarad) or 'mF' (millifarad), although the former is more likely.

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.

line sync · 21st Apr 2019, 11:07 pm

Thanks for all your help guys.

Robin

Maarten · 22nd Apr 2019, 12:29 am

Quote:

Originally Posted by julie_m

What was the aversion to "nano" all about?

I don't think it was aversion, just not the usual way to express values.

Maarten · 22nd Apr 2019, 12:32 am

Quote:

Originally Posted by stevehertz

Quote:

Originally Posted by Maarten

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.

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.

Well, it makes a good parallel with the way resistors are marked so you could also think of it as easy to remember. 103 is always 10k, whether it be a resistor or a capacitor. Also: some capacitors use colour codes (bumble bees, MELF, axial ceramics) and some resistors (specifically SMD) use the same numbering system.

joebog1 · 22nd Apr 2019, 1:42 am

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

Restoration73 · 22nd Apr 2019, 8:59 am

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.

20th Apr 2019, 10:44 pm	#1
line sync Heptode Join Date: Sep 2009 Location: Kinver, Staffordshire, UK. Posts: 634	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
sortedradio Heptode Join Date: Jan 2008 Location: Sheffield, South Yorkshire, UK. Posts: 655	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 __________________ Martin BVWS member GQRP Club

21st Apr 2019, 6:46 am	#3
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,658	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. __________________ Curiosity hasn't killed this cat...so far.

21st Apr 2019, 6:18 pm	#4
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	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
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: capacitors values What was the aversion to "nano" all about? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

21st Apr 2019, 8:51 pm	#7
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	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.

21st Apr 2019, 11:07 pm	#9
line sync Heptode Join Date: Sep 2009 Location: Kinver, Staffordshire, UK. Posts: 634	Re: Capacitors values Thanks for all your help guys. Robin

22nd Apr 2019, 1:42 am	#12
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	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
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	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.