About Midwest Devices LLC

Midwest Devices LLC manufactures the Capacitor Wizard® in-circuit Capacitor ESR analyzer. The Managing Member is Doug Jones, the designer of the Capacitor Wizard®. In 1970 Doug opened Independence Electronics Inc, an electronics service company. In 2007 Doug moved the manufacturing to Midwest Devices LLC.

Pioneers of Modern ESR (Equivalent Series Resistance) Testing

Prior to 1995 few technicians had even heard of ESR. They certainly didn't know how to measure ESR. Capacitor manufacturers alluded to ESR by reference to a capacitor's "Dissipation Factor". Through Capacitor Wizard® articles in major electronic magazines of the time (Radio Electronics, Television Magazine, etc.) and testimonials from Capacitor Wizard® users, the industry has discovered the necessity of measuring ESR.

In 1995 most capacitor manufacturers did not even quote ESR in their catalogues. Today they all quote ESR specs. Most electronic technicians now know about high ESR's detrimental effect on capacitors and high speed circuitry. We are pleased to say that our early pioneering efforts exploring ESR have had a positive effect on the industry.

About the Capacitor Wizard®

In 1995 the possibility of testing a capacitor for ESR (Equivalent Series Resistance)was brought to Doug's attention. The idea intrigued him so he immediately looked up ESR details. There was very little information available in 1995.

After his observations, he discovered that what ESR information was out there was full of misinformation. He used the basic definition of ESR to build a crude but valid test condition. In a day or so he was accurately measuring ESR with a square wave generator and an oscilloscope. (More details are in the article, ESR Measurement Using Square Wave [PDF].)

An easier means of measuring ESR was needed. Doug decided to make a portable ESR meter. He wanted 10 times more sensitivity than needed at the time. And to measure IN-CIRCUIT! The result was the Capacitor Wizard®.

Testing the Capacitor Wizard®

Doug had all of his friends in the TV/electronic repair business testing the Capacitor Wizard®. The results were startling, even to him!

Everyone was amazed at how fast they found bad capacitors and how many bad capacitors they had overlooked over the years. They even discovered other uses such as finding bad video heads on tape recorders!

Doug asked his friends to save their bad capacitors so he could verify the Capacitor Wizard®'s analysis. All the shops bought at least one Capacitor Wizard®, several bought more than one. He new he had a winner!

Doug Jones

About Doug Jones

Doug is a member of several professional engineering associations. He has an amateur radio license N0CDT and a professional radio-telephone license. He studied physics, chemistry, computer programming, drafting, and math at the University of Missouri, Columbia. He is a 1965 graduate of the Kansas City, MO VoTech electronics school, studying both tube and solid state design principles. Over the years Doug has designed, manufactured and sold several different kinds of test equipment. He has major experience in all types of contract electronic repair.