# What is the minimum value of capacitance of a rotating capacitor ???

#### MisterBill2

Joined Jan 23, 2018
8,405
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.

#### MisterBill2

Joined Jan 23, 2018
8,405
I have not seen any response at all from the TS, and they are only listed as having one post. So I wonder.......

#### DickCappels

Joined Aug 21, 2008
7,246

#### Audioguru again

Joined Oct 21, 2019
2,962
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.

#### Beau Schwabe

Joined Nov 7, 2019
82
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

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#### Tonyr1084

Joined Sep 24, 2015
5,855
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.