Geller
Labs 

Using an Ohm Meter to Measure High Capacitance Values (work in progress, be sure to hit refresh to pick up our latest changes and entries) Not too long ago, I needed to measure the capacitance of some relatively high value electrolytic capacitors, 10,000 uF, and 17,000 uF. Our Agilent 34410A DMM only measures capacitance to 100 uF, and none of our impedance bridges go above 1,000 uF. It has been well discussed over the years how to use an ohm meter transient reaction to "check" a capacitor. However, I've never seen a note on how to use an ohm meter to determine the capacitance value. It turns out that many bench meters use a constant current source in the ohms mode. So, I investigated how to use a bench meter ohm meter scale to measure the capacitance of my 10,000 uF and 17,000 uF capacitors using constant current charging. Here are some notes on how to "Use an Ohms Scale to Measure High Capacitance Values", which references a note on how to review how your bench meter ohm meter measures ohms (investigating the ranges of constant current for various ohms scales). Since I made those intial high value capacitance measurements, we purchased an Agilent 1733C hand held LCR meter that has capacitance scales to 20,000 uF (20 mF), ESR, D, and DC ohms scales for Cs and Q and L measurements for inductors, as well as builtin test frequencies from 100 Hz to 100 kHz (with some limitations). It is a remarkable cost effective instrument! See the U1700 family of C and LCR meters in this U1700 series comparison chart.
COPYRIGHT © 2011 JOSEPH M. GELLER

