On the left is a 1970’s Heathkit Capacitor Tester. Even though it is old, They are still sought after today because they can test capacitors for leakage up to 600 volts. Very few modern capacitor testers can do this. This tester does not do more sophisitiated tests such as ESR though. I am in the process of rebuilding this instrument by replacing the old electrolytic capacitors and any other components that are out of tolerance. Also all of the switches will be cleaned with Deoxit D5 contact cleaner. Then it will be aligned and tested and put on my workbench.

The left and right side of the capacitor tester are shown on the left. The circuits consist of a 600 volt power supply and a balanced bridge circuit that uses precision components which can determine a capacitors value and a variable voltage circuit to test capacitors for leakage up to 600 volts. If a capacitor has any leakage, the eye tube will not open.

Modern LCR tester is pictured on the left. It can test and measure L (inducters), C (capacitors), and R (resistors).

Capacitors are measured in fractions of a Farad, from picofarads on up. It can also measure the ESR (equivalent series resistance) of a capacitor. As capacitors age or fail, they do not block DC voltage anymore and begin to act like a resistor, hence: ESR. Old resistors often change values and require replacing. Inductors can short or open.

A good voltmeter is a requirement on any workbench. Most are digital today. I still keep an analog meter or two around though. This meter has autoranging on some of its functions, which is handy.