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CORRECTION: Capacitor measurements
I found an error in the capacitance measuring info I posted (the rule of
thumb about desired voltages in the last paragraph is wrong). Here is a
corrected version:
4) Easiest way: you can make a voltage divider:
|------------------------------
| |
| resistor
| |
120 volt AC (wall plug) |
| |
| capacitor
| |
|------------------------------
Measure the voltage across the resistor and the capacitor. Don't get
zapped - you are playing with line voltages here and there is not much
between you and eternity.
C = (Vr / R) / (2 x pi x f x Vc)
where Vr is the voltage across the resistor, R is the resistor in ohms,
pi is 3.141, f is 60 Hertz (or 50 in some countries - you know who you
are), and Vc is the voltage across the capacitor.
You should probably to have Vr and Vc be within an order of magnitude of
each other. I found this to give the best accuracy when measuring the
main cap on my coil. Resistors in the range of 50k to 500k worked well
when measuring my .005 uF cap.
Steve Falco
sfalco-at-worldnet.att-dot-net