An analyse on analogue ESR-meter

The paper presents an analogue ESR meter, made with a JFET integrated circuit, which can be used to identify defective electrolytic capacitors. It is powered by continuous voltage and consists of a differential voltage source, a 100 kHz oscillator, a Wheatstone bridge with resistors supplied with alternating voltage, in a connecting arm of bridge being connected the electrolytic capacitors to be checked, a voltage amplifier-comparator with optical warning, a high-pass filter and a voltage-current converter. At the output of voltage-current converter is a milliammeter pointing out the ESR value (up to 20 Ω). Measurements were made on a batch of electrolytic capacitors (new and used) and a comparative analysis was performed between the measured values with an analogue ESR-meter and a digital one.