poor man's fein/festool vac load sensing switch

[Matt Meiser]

But you'd have the satisfaction of saying you made it. And you could probably find some kind of new tool that you would NEED to buy for the project

Grainger doesn't carry the current sensor used in the project any more either. They do carry a more expensive one at about $75.

[Sam Shank]

Here's a link to a guy who built one for his stereo. I think it could be modified to handle more amps.

http://sound.westhost.com/project79.htm

[John Seiffer]

I have the Sears one. It was about $20. Works great.