Page 1 of 1
Posted:
Fri May 21, 2004 6:34 pmby bnelson
Thought I would share a picture of the latest idea I'm working on for pressure control on my bench. My bench doesn't have any bleeder valves or throttling valves to control pressure, so I have to adjust the speed of one or more fans. I first tried a cheap router speed control that wasn't worth a hoot, however this new device works like a charm. It is a continuously variable autotransformer. This one is made by Superior Electric. It is a model 136BU rated at 0-120volts or 0-140volts and 22amps. Please excuse the hay-wire installation, this was just a test to try it out. It will run 2 fans that can be individually turned on or off when I'm done.
Posted:
Fri May 21, 2004 9:27 pmby 84-1074663779
Absolutely....
They are big and heavy, but one of those will last a lifetime. They will also handle motor startup current peaks easily, and high voltage transients from sparking brushes.
Various types of electronic speed controls tend to go poof, bang, smoke, or burst into flames. I hate them, and I am a retired power electronics engineer.
Check out e-bay, these things are called "variacs" and are readily obtainable secondhand in various amp ratings.
Posted:
Sat May 22, 2004 2:03 pmby bnelson
Ditto what Tony said. This one was an ebay item. Cost me $56 plus the shipping. Over several hundred new, possibly up to $400 or so. This one has little or no previous use and came in the original box with instructions and dial bezel. Ebay definately the place to find one at a fraction of new cost.
For those of you looking for one they are available in sizes starting at a fraction of an amp to sizes that would run an entire bench. Some are also available motorized for remote control or control by say an automatic pressure control device. A couple of the brands that tend to be real common are Staco and Superior Electric, both of which are American made and still in business. Other search words when looking on ebay would be Variac, autotransformer and powerstat.
Posted:
Sat May 22, 2004 8:36 pmby 84-1074663779
These can also be used to slow any brush type ac motor in power tools that did not originally come with an inbuilt speed control.
I use one on my large power drill for cylinder honing. It can slow things down to the point where it is extremely easy to get the desired honing cross hatch pattern. Most big drills even on slow speed go much too fast.
It will not work on induction motors though, it MUST be a brush type motor.