The circuit shown here tackles ESL/ESR measurement of capacitors by using a mercury-wetted relay (Fig. 1). In this circuit, the relay is employed as a fast closing switch.

A 9-V battery or an optional ac wall adapter can power the Model 881 portable in-circuit equivalent-series resistance (ESR) and dc resistance (DCR) capacitor tester. It measures ESR and DSR from 0 ...

The ESR function can also be used to measure the resistance of things like transformer windings and coils. It shuts itself off 15 seconds later, conserving the battery. Capacitance and ESR are not the ...

Looking to recap a vintage radio chassis? Then you might need to measure the equivalent series resistance of the capacitors, in which case this simple five-transistor ESR meter might come in handy.