Fig.1: simplified cross-section of an electrolytic capacitor. The dielectric consists of a thin layer of aluminium oxide on the anode plate and this is connected to the cathode plate via an electrolyte-soaked separator.

It's hard to believe that it’s already eight years since my first ESR (equivalent series resistance) meter was described – in the January 1996 edition of "Electronics Australia". It was designed on a 386 PC!

The ESR meter allowed service technicians to quickly and easily identify defective electrolytic capacitors while they were still in circuit. It measures a characteristic of electrolytic capacitors which is very important: the "equivalent series resistance" or ESR.

Back then, no-one (including myself) expected that a meter designed to measure a capacitor characteristic hardly anyone had ever heard of would become popular in Australia, let alone overseas. However, we didn’t consider the explosive growth of the Internet. Thanks to people discussing it on various newsgroups and by email, about 12,000 ESR meter kits have now been sold and sales (mainly outside Australia) continue to be strong.

Over those eight years, both Dick Smith Electronics (which sells the kit) and the author have received many suggestions from constructors on improving the ESR meter kit – particularly on making the construction easier. This upgraded version is the result and incorporates many of those ideas. As before, it will be available as a complete kit from DSE.