06-10-2015, 04:54 PM
A quick point on nomenclature.
When you write 0.22mF you almost certainly mean 0.22 microfarads. For lazy folk like me we usually write 0.22uF or even just 0.22u where there's no ambiguity. (Terry will slap me on the wrist for not using the "mu" symbol instead of "u" but as I siad, I'm lazy and there's no loss of meaning) Strictly speaking 0.22mF means 0.22 millifarads or 2200uF, a very different beast.
Old components and diagrams used a whole variety of ways of writing values. MFD or M.F.D being common for microfarads. Go back even further, to the early 1920s and further, and the units are even more wierd and wonderful.
Coming up to date modern engineers often write 220nF (or just 220n) meaning 220 nanofarads. Exactly the same as 0.22uF but without a decimal point to get lost. We even write 4n7 for 4700pF or 0.0047uF. Again saves losing a decimal point or interpreting lots of zeros.
Finally in the old days we often used 0.2uF or 0.5uF etc. These days we use the closest preferrred values 0.22uF and 0.47uF and this will be OK except in a very few cases.
And as Joe says, service data can be incorrect. Or the jolly bodger may have been there before you.
When you write 0.22mF you almost certainly mean 0.22 microfarads. For lazy folk like me we usually write 0.22uF or even just 0.22u where there's no ambiguity. (Terry will slap me on the wrist for not using the "mu" symbol instead of "u" but as I siad, I'm lazy and there's no loss of meaning) Strictly speaking 0.22mF means 0.22 millifarads or 2200uF, a very different beast.
Old components and diagrams used a whole variety of ways of writing values. MFD or M.F.D being common for microfarads. Go back even further, to the early 1920s and further, and the units are even more wierd and wonderful.
Coming up to date modern engineers often write 220nF (or just 220n) meaning 220 nanofarads. Exactly the same as 0.22uF but without a decimal point to get lost. We even write 4n7 for 4700pF or 0.0047uF. Again saves losing a decimal point or interpreting lots of zeros.
Finally in the old days we often used 0.2uF or 0.5uF etc. These days we use the closest preferrred values 0.22uF and 0.47uF and this will be OK except in a very few cases.
And as Joe says, service data can be incorrect. Or the jolly bodger may have been there before you.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
