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Re: [TCML] Measuring capacitance


There's really no direct way to convert "Ohms to Farads" from the ohm
scale of a standard multimeter. With the old-style analog multimeter, you
could place your meter in one of the ohmic resistance ranges and place
the test leads across the terminals of the test capacitor. The needle indi-
cator would slowly move from a low resistance reading toward an infinite
resistance reading, I believe?, because the resistance function of the multi-
meter checked for resistance by applying a small voltage to the test resis-
tance through it. This small voltage would also enter the test capacitor and
chagre it up, which would cause the scale deflection.The larger the capaci-
tor, the slower this deflection would occur. However, I don't know if this
method would work with a modern DMM.? Anyway, all that this method
of testing could really determine was if the capacitor in question was good
or bad.

Capacitive measuring meters (usually LC meters, which can measure both
capacitnace and inductance) are just about always available on eBay for a
reasonable price (dirt cheap if you don't mind China made). I have a chea-
py Chinese made (eBay special) LC meter that actually works quite well
and gives pretty accurate capacitive measurements. Certainly adequate for
my hobby level use. Think it cost me < $20, IIRC.



David Rieben

----- Original Message ----- From: "Brandon Hendershot" <mrbrandman@xxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, November 26, 2009 1:32 PM
Subject: [TCML] Measuring capacitance

I'm looking to make a new tank cap this Christmas and I'd like some help from a meter to measure the farad rating to aid wiring the in a mixture of series and parallel. The only thing I can think of that would measure farads is an ohmmeter. Do they make a farad meter? If not, how do you convert ohms to farads?
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