Capacitor codes: Difference between revisions
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It's essential to be able to read '''capacitor codes''' in order to correctly recognise the correct part and as the schematic, BOM and component supplier might use pF, nF or µF interchangeably to be able to '''convert''' between these. |
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== EIA scheme == |
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The Electronic Industry Alliance (EIA) has standardised some of the marking schemes.<ref name="ccam"/> |
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== Leaded == |
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On larger capacitors their value is printed on the case or encapsulation. The values of small capacitors are indicated in an alphanumeric code. With older capacitor values were sometimes indicated by a colour code.<ref name="ccam">[https://www.electronics-notes.com/articles/electronic_components/capacitors/capacitor-codes-markings.php Capacitor Codes & Markings], Electronics Notes</ref> |
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⚫ | With small general purpose capacitors where values range from a few pF to less than 1 µF the convention arose that whole numbers designate values in picofarads while decimal fractions designates values in microfarads.<ref name="rcv">[https://web.archive.org/web/20120814104332/http://www.play-hookey.com:80/dc_theory/capacitor_values.html Reading Capacitance Values] by Ken Bigelow</ref> |
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Often p, n and u are substituted for the decimal point. For example 8p2 for 8.2pF, n51 for 0.51nF or 4u7 for 4.7µF. |
Often p, n and u are substituted for the decimal point. For example 8p2 for 8.2pF, n51 for 0.51nF or 4u7 for 4.7µF. |
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=== Working voltage === |
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Where there is space the working voltage is given. For smaller capacitors this needs to be found from the data sheet.<ref name="rcv"/> |
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=== Polarity === |
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Care must be taken to insert polarised capacitors in the correct orientation. The stripe on radial or arrow on axial aluminium electrolytic types indicates the negative lead. On tantalum types a + sign indicates the positive lead.<ref name="rcv"/> |
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=== Stripe === |
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Unpolarised capacitors with a stripe ... |
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=== Small values === |
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For small value capacitors the letter R is used to denote a decimal point.<ref name="ccam"/> |
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=== Abbreviated marking codes === |
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A newer way to mark values is with three numbers on the body of the capacitor with the value in picofarads. The first two digits are the significant figures and the third the multiplier (i.e. number of zeros). So for example 151 indicates a capacitance of 150 pF.<ref name="rcv"/> |
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=== Temperature coefficient === |
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== SMD == |
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... |
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== References == |
== References == |
Revision as of 23:11, 19 January 2021
It's essential to be able to read capacitor codes in order to correctly recognise the correct part and as the schematic, BOM and component supplier might use pF, nF or µF interchangeably to be able to convert between these.
EIA scheme
The Electronic Industry Alliance (EIA) has standardised some of the marking schemes.[1]
Leaded
On larger capacitors their value is printed on the case or encapsulation. The values of small capacitors are indicated in an alphanumeric code. With older capacitor values were sometimes indicated by a colour code.[1]
With small general purpose capacitors where values range from a few pF to less than 1 µF the convention arose that whole numbers designate values in picofarads while decimal fractions designates values in microfarads.[2]
Often p, n and u are substituted for the decimal point. For example 8p2 for 8.2pF, n51 for 0.51nF or 4u7 for 4.7µF.
Working voltage
Where there is space the working voltage is given. For smaller capacitors this needs to be found from the data sheet.[2]
Polarity
Care must be taken to insert polarised capacitors in the correct orientation. The stripe on radial or arrow on axial aluminium electrolytic types indicates the negative lead. On tantalum types a + sign indicates the positive lead.[2]
Stripe
Unpolarised capacitors with a stripe ...
Small values
For small value capacitors the letter R is used to denote a decimal point.[1]
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|
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Abbreviated marking codes
A newer way to mark values is with three numbers on the body of the capacitor with the value in picofarads. The first two digits are the significant figures and the third the multiplier (i.e. number of zeros). So for example 151 indicates a capacitance of 150 pF.[2]
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Temperature coefficient
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SMD
...
References
- ^ a b c Capacitor Codes & Markings, Electronics Notes
- ^ a b c d Reading Capacitance Values by Ken Bigelow