Build The Amazing FET Circlotron — Michael Rothacher / 2008

Cue the Theremin music! This article is about building your own all-FET Circlotron. It smashes atoms. No, strike that. It won’t smash atoms like a cyclotron, but it has a really cool name and it is, technically speaking, powered by atoms and very, very good at amplifying music. Alpha M. Wiggins of Electro-Voice is generally recognized as the inventor of the Circlotron amplifier although other inventors developed similar circuits around the same time period in the 1950’s. The Circlotron’s transformer-coupled vacuum tube output circuit, a floating bridge, was often drawn in a circular fashion; hence the name. Later, Circlotron-type output… More...

Zen Variations 2 — Nelson Pass / 2002

Welcome back to the Zen Amp Variations. This is part 2 of many parts in which we explore some of the ways to make a very simple audio amplifier. In this and parts 3 and 4 we will embellish upon the original Zen amplifier circuit, improving the performance and creating the Penultimate Zen Amp. You may recall that the Zen Amp is a single MOSFET transistor operated in what is known as Common Source mode in which the input signal is fed to the Gate pin, the Source pin is grounded, and we take the output signal off the Drain.… More...