Aaron Newman and Mike Beigel founded Musitronics and launched the popular Mu-Tron pedal series in 1972. In 1976-1977 musicians Lol Creme and Kevin Godley from 10CC developed a guitar sustainer, the Gizmotron. Musitronics became the Gizmotron manufacturer. The Gizmotron proved difficult to make and was temporamental in use. The Gizmotron used mechanical plastic parts but none of the Musitronics staff were experts in engineering plastics. For example they found that that units made during the winter wouldn't work properly in hot weather.

Musitronics didn't have enough money to produce both the Gizmotron and the Mu-Tron line, and the company directors decided to sell Musitronics to ARP, a synthesizer company (that was in the process of developing a doomed guitar synth called the Avatar). ARP was meant to pay royalties on the Mu-Tron line, but they folded before Newman and Biegel collected a cent. They became Gizmo Incorporated and continued to try market the Gizmotron, but then Newman had a heart attack and the project was wound up. Newman later worked as an insurance agent and Mike Beigel continues to work as an electronics designer and consultant.

Starting in 2012, Mike Beigel began to “resurrect and re-invent” the original Musitronics Mu-Tron product and the rest of the product line. Beigel named the product line Mu-FX™ by Beigel Sound Lab, since the “Mu-Tron” and “Musitronics” trademarks had been "acquired" in the USA by third parties. Mu-FX began producing a modified and miniaturized version of the Mu-Tron III, renamed the Tru-Tron 3X. A few years later, the Micro-Tron 3 was introduced. Around 2017 Mu-FX/Biegel regained the Mu-Tron brand name.

Source: Mu-FX website (archived 2015)