Please keep in mind that while the TS does not specifically describe the cap, it is probably one with plates. Fortunately the method I described works for most kinds with low losses.

 

Hello,

This page tells you more about the properties of variable capacitors:
http://www.iequalscdvdt.com/Trimmer_Capacitors.html

Bertus

 

I have not seen any response at all from the TS, and they are only listed as having one post. So I wonder.......

 

Maybe found an answer elsewhere

 

The TS probably turned the variable capacitor to minimum then removed it from his solderless breadboard. Then he noticed that the frequency did not increase due to the massive stray capacitance of the rows of contacts and messy wires all over the place.

 

I have made a linear variation of the rotating butterfly cap where multiple plates interdigitated one another by coming together or pulling apart. There are also sleeve style capacitors that could be considered linear where you have a male and female type of housing with a dielectric insulator to prevent any shorting.

With regard to the original question, minimal capacitance is going to come down to 3 main things.
1) Total surface area of the plate(s)
2) separation distance of the plates from one another...
a) This can be sliding (rotation, linear, etc.)
b) Or physical plate to plate parallel distance
3) dielectric used between the plates (air, paper, etc.)

Humidity and Temperature will also play a role

 

Sometimes one may ask a simple question and get tremendously hard to follow answers. This may result in one giving up on learning the answer. For instance, how does one calculate the distance from Earth to a distant star? Simple enough question. But the answer (which I don't know) may involve a higher level of math, one that someone like me might not know or be proficient with. The end result is the questioner giving up on seeking an understanding to the answer.

It looks like our new member has decided that capacitors are beyond his current ability to understand the answers.