trimmer capacitor value

[daviddoria]

once you set a trim cap, how can you tell what capacitance it is set to so you can replace it with a nonvariable capacitor?

 

[kinjalgp]

A capacitance meter which comes with new digital multimeters can do your job.

 

[daviddoria]

arghhh i just bought a multimeter not too long ago but it doesn't have that ;(

2 more questions that go along with that...

1) to make sure i am not stupid, what would a capacitance meter symbol look like on the multimeter, hope i didn't just miss it

2) what would be a good one to get that has everything and what would the price range be and where would i get it ?

thanks again

 

[Phasor]

If you can afford it, Fluke is probably the best brand. I use a "Brymen 202", which seems to perform quite well.

A capacitance symbol on a multimeter may either look the same as a capacitance symbol on a schematic (one straight line and one curved line), or it might have the letters nF or uF.

My Brymen meter costs about AUD$130. A "cheap" Fluke meter is around AUD$250.

Be aware, though, that for measuring very small capacitances, like those in trimmer caps, a multimeter may not provide great accuracy. You may also need to "zero" the meter, due to internal capacitances (on mine I do, on Flukes there is no need).

You can also use an 'LCR' meter, which measures inductance, capacitance and resistance.

Also don't forget, that to measure the capacitance of your trimmer, you need to isolate at least one leg from the rest of the circuit (ie, desolder it from the board).

 

[daviddoria]

again, thanks for the great answer.

does anyone know the cheapest place to get a fluke or brymen?

thanks
david