Category: Electronics

A thought came to mind that when I need a PID controlled process or something on the side of industrial automation I just take an old “recycled” controller that was bound for the garbage heap and I make whenever I need. That’s great for me; my blog readers, not so much. I recently replied to a posting on an electronics forum with a guy looking for a cheap and easy way to control is variable frequency drive (VFD). This is a device that varies voltage and frequency to vary the speed of a motor. You can buy these in single phase for fractional HP motors thought they’re more commonly used in three phase applications. The poster was looking for a way to vary the control voltage (0-10V). I bit my tongue through the comments from people misunderstanding that it was control voltage an in fact the guy didn’t need a 10V 300A power supply. In his case he wanted to manually adjust the speed, but if it was to be an automated process and if I was him; I’d used a stand alone PID controller. These controllers are great for a pool pumps, hot water solar panels, exhaust fan controls, or something along those lines. I would use the Johnson Controls System 350 series controller. http://www.johnsoncontrols.com/content/us/en/products/building_efficiency/commercial-refrigeration/system-modular-control/350controls/a350/sysa350p.html

You can get these to control off temperature, humidity, or pressure to vary your output. They also come in staged outputs. I’ve seen these for green house controls, water pump VFDs, etc etc. It’s pretty simple; have a control sensor, and command an output, adjust the set-point and proportional band/integration to “tune” the loop.

Full disclosure: I work for Johnson Controls, However! I do not/can not sell or install these. These are generally installed by electricians but trust me.. anyone could install one of these. I’ve played around with them from a condenser deck we were working on one time. You can pick them up at grainger or anywhere you can buy HVAC components, likely eBay as well?

.. also forgive the liberties I took with “PID”, I do realize it’s only a PI controller. It’s rare to find full PID implemented in an industrial or energy automation controller; we usually don’t need to use derivative.

I was looking for some interesting news sites for electronics as I do from time to time. Not much out there… well at least none with articles that were of immediate interest to me.

I came across this article and nearly commented but it was from 2007 with zero comments, so there wasn’t much point:

http://electronicdesign.com/archive/whatever-happened-electronics-hobbyist

I’m an amateur radio operator/builder, I like building embedded systems and I’ve built a robot, so I guess I get to fit into all three of his “types” of electronics hobbyists of the future. I think he’s probably right on with the separation of electronics hobbyist .. unless you count students; I wouldn’t. Is that a big deal? I don’t think so. Technology had made it difficult to take the old “easy” kits to offer to youth to spark some interest. Who knows how long AM will be around? Give it a decade and someone will be leaning heavy on the FCC to shut it down and sell off the spectrum. AM isn’t making any money these days.  This article also feels a little “back-in-my-day” which gets eye rolls from anyone under 40.

So my only real beef with this article is his opinion that QST is a quality magazine that supports electronics hobbyist… I totally disagree. QST isn’t worthy of toilet paper in my opinion. It’s the ‘US Weekly’ of electronics magazines. All Ads, back-in-my-day articles, and sponsored reviews. QEX on the other hand is an EXCELLENT magazine, we are in agreement there. I would recommend QEX from non-hams if they’re looking for more reading material as there are plenty of projects that could be re-purposed.

If anyone coming across this happens to have some “favorite” generic hobbyist news feeds drop me a comment. I’m always looking for interesting articles.