What kind of capacitor is this? How to read its value code?

Question

I have found some capacitors like this one:

Does anyone know what kind of capacitor it is? How can I read its value?

Answer 1

These images appear to have your answer. This capacitor is a 0.01µF 250v capacitor from old electronic equipment (most likely radio, audio, or television related) containing vacuum tubes. It is similar looking to some of these which are old mica capacitors:

The stripes on the capacitor can be interpreted using the standard resistor color code to give a 3-digit code like on standard capacitors, where the third digit is the multiplier. In order to read the capacitor code, simply multiply the number created by the first 2 digits by 10^multiplier to get the final value in pF.

With resistors, the last stripe indicates the tolerance, but with older capacitors it indicates the voltage. If a tolerance is not specified, it is usually 20%.

Answer 2

When electronic parts are marked with a color code, it is in floating point. Each color represents one digit value according to the standard color code. The first digits are the mantissa, and the last the power of 10 to multiply it by. For a small capacitor like that, the base unit is almost certainly pico-Farads.

One band will be different somehow. The number is read ending immediately before that band, which usually specifies a tolerance. These are less standard and therefore require knowing the manufacturer to know for sure.

You have BRN BLK ORN, so 1 0 3, which means 10 x 10³. We presume pF, so 10,000 pF which means 10 nF in regular engineering notation. Again, the dotted red band could mean various things, like 20%, or a voltage range, or something. Without identifying the manufacturer and then finding the appropriate datasheet, you can't be sure.

For this size 10 nF cap, I'd expect maybe around 200 V capability.