[Prev][Next][Index][Thread]

Re: Measuring Capacitance



> By the way, methods #4 and #5 can both be checked for error very
> simply: After measuring the voltages across each component, add these
> values together and compare them to the actual measured voltage across
> BOTH components. If they don't add up within a few percent, then your
> meter is loading down the circuit.

I think this error check works for method #5 but not for method #4. 
When I measured a 550k resistor and a 4500 pF capacitor in series across
120v -at- 60Hz, I read roughly 0.8 volts across each component.  I believe
that this is due to the different phase shifts across the resistor and
capacitor in circuit #4.

As another example, the book I got this technique from had a 4k resistor
and 0.7 uF capacitor in series across 115 volts, with Vr = 80 and Vc =
100.  Thus the voltages may add up to less than the line voltage, or
more than the line voltage, again because of the phase shifts.

	Steve Falco
	sfalco-at-worldnet.att-dot-net