I found this diskussion in another forum, but not much help.

Well at least you aren't the only one to struggle with it.

Thanks for pic. I still can't figure it out. One problem is I'm not sure if the meaning of a dot at the top is the same as the top being dipped.

I start off on the left with 47pF, then 680pF, then 2200pF=2.2nF (maybe), then I get to the dipped tops and I think hmmm, maybe I'm on the wrong track, or maybe they are coded differently.

One trick in measuring small values is to put many parts of the same values in parallel, measure them, then divide the measurement by the number of parts in parallel. If you still can see 1nF with 5 parts in parallel then at least you know they are less than 200pF - it does give you some information.

I'd start with the third cap, then the second then try the end two. The fourth one is weird.

Another way is to build an RC oscillator with say an NE555 and measure the frequency. The easiest way is to put in an unknown cap, measure the frequency, then by trial and error put in known caps to get a frequency close to the unknown value.

It is also possible find the values using calculations but you have to work out the stray capacitance in the circuit first. eg. put in a known 100pF cap , measure the frequency, calculate the expected frequency for a 100pF cap. You will find the measurement is lower then you estimate what extra capacitance the circuit had, which might 30pF or so.

It is often better to leave a cap in the circuit (maybe an extra 33pf or 100pF) so the oscillator frequency has a maximum value. Using this scheme I have been able to detect 0.1pF or so.