value of a trimmer capacitor.

[amriths04]

hi friends,
when we turn the screw of a trimmer capacitor, how do we know its capacitance at that point?

thank you,
amrith.s

 

[ahmed_nasr]

i think this can be done by knowing the ratio of the rotation to the full rotation ... this is an approximate method

 

[amriths04]

but do you think it will be a linear relationship?

thank you,
amrith.s

i think this can be done by knowing the ratio of the rotation to the full rotation ... this is an approximate method

 

[ahmed_nasr]

yes i think it's linear because C=εA/d

and A= overlapped area = 0.5*Φ*(r^2)

where Φ=overlap angle

i.e C is directly proportional to Φ i.e linear relation between C and Φ

 

[amriths04]

oh ok. thank you, ahmed_nasr.
amrith.s

yes i think it's linear because C=εA/d

and A= overlapped area = 0.5*Φ*(r^2)

where Φ=overlap angle

i.e C is directly proportional to Φ i.e linear relation between C and Φ

 

[ahmed_nasr]

u r welcome ... plz click on " helped me" button if that was helpful

 

[echo47]

If it's a compression trimmer, the relationship is non-linear. In case you've never seen one:
http://www.spraguegoodman.com/500/500p1.html

I measured an Arco 402, turning the screw approximately 30 degrees per measurement: