# Capacitor values in Kp

#### peacocksuit

Can anyone help me understand the capacitor values on this circuit? They're given in P and Kp. Some of them don't have K or KP, just a number. I was thinking the P denoted Pico farads, but it still doesn't really make sense to me. Say '10kp', is that saying 10,000 Pico farads?

Thanks đź‘Ť

#### Netlist

Paid Member
Say '10kp', is that saying 10,000 Pico farads?
Yes, you are correct. The 'k' stands for kilo an the 'p' for pico. 1k5p would be 1.500pF or 1.5nF. Electrolytes are in ÂµF.

Hugo

1 users

#### MarcelvdG

It's an antique notation from way back when the prefix n for nano hadn't been invented yet.

1 users

#### Netlist

Paid Member
Oh, didn't know that... I remember the cm notation on very old caps.

Hugo

1 user

Thanks all

1 user

#### HalFoster

Paid Member
Just to add to the confusion: uuF (micro micro farad) was often used in place of pF as well. And when it comes to resistor values, 10M often meant 10K - "meg" was spelled out for megohms.

1 user

#### peacocksuit

I'm not sure why someone has drawn this circuit out in the modern age and not just used the modern way of expressing the values

#### peacocksuit

Also, what about the 2 which are just marked '1000'? Thanks

#### HalFoster

Paid Member
They are drawn as polarized so I would guess they are 1000uF electrolytics.

1 user

#### MarcelvdG

Oh, didn't know that... I remember the cm notation on very old caps.

Hugo

To be honest, I don't really know it either, it's just my guess that kilopicofarad was used when nanofarad didn't exist yet.

Regarding centimetre as a unit of capacitance, that's the self-capacitance of a spherical conductor with a radius of 1 cm in an infinite vacuum, about 0.9 pF.

#### MarcelvdG

Thanks for the correction, I had it upside down.

When mu0 was still 4 pi * 10-7 H/m and the speed of light in vacuum was already 299 792 458 m/s, a sphere with a radius of 1 cm in an infinite vacuum had a self-capacitance of exactly

100 000/(299 792 458)2 F.

That's indeed about 1.1 pF, not 0.9 pF.

You can calculate it from the equations of the speed of light in terms of epsilon0 and mu0 and the equation for the self-capacitance of a sphere.

1 user

#### Netlist

Paid Member
It wasn't meant to correct you.
Great math, a bit above my head but now I see where we come from.

Hugo

#### lcsaszar

The electrolytic capacitor in the top middle is denoted 100kp, it is either 100nF non polarized, or 100uF, but then it should have been drawn 100 according to the old logic. 100uF is more likely.