I always served two masters: hardware and software. In the early part of my career, I designed mostly hardware, such as control systems, computer interfaces, and data acquisition. Over time, there was greater demand for software, so that’s what I do for a living today. These days, hardware is more of a hobby than a profit center.

Recently, my interest in hardware has re-emerged. Fortunately, I’ve set up a nice bench with test equipment and soldering iron ready for action. I’ve been meaning to document some of circuits I’m working on. This article is a step in that direction.