Oh, that was so many years ago! But my system still works great!
There are many ways to "automate" or semi-automate your DC. I like, many folks, didn't like it when I misplaced my remote, so I put low voltage DC control buttons in convenient locations around my shop. Then I thought it would be nice to automate this process, then I took an honest look at what I really wanted in the way of automation. It wasn't for the wow factor, it wasn't to turn on the blower, though that is still necessary, but what I really wanted was have my blast gates open and close automatically- because I am essentially lazy. When I would quickly jump from machine to machine, more often than not I would neglect to turn on the DC and/or open/close blast gates. So, using parts from Ebay, surplus companies, etc., I built a totally automated electro-pneumatic machine-triggered system.
Current sensor switches at each power outlet detect whenever I turn on a machine. These sensors cause solenoid air valves to port low pressure (8 - 15 psi) shop air to pneumatic cylinders that open (and close) the adjacent blast gates. A secondary sensing circuit detects when any gate is opened and starts the DC blower. I did some scrounging so total cost for each complete station was only about $30. It will be difficult today to do it as inexpensively. Some folks have built DIY electro-mechanical autogates using solenoids or motor/leadscrew/follower actuators, but, for a number of reasons, I decided that pneumatically operated gates would be the best and easiest for me to build.
Norfab and others make some very expensive pneumatically actuated, commercial-grade, metal autogates. At least two companies GrnGate (formerly ECO Gate) and iVac (available at Infinity Tools, Lee Valley, Rockler, etc.) make slightly less expensive electro-mechanical gates for the hobby and the small commercial woodworking shop markets. They rely on current sensors and PLC (logic) modules to control the blast gates and the DC. I believe GrnGate only make 4" gates. Last year iVac introduced new metal 4" and 6" autogates. Each 6" metal iVac gate sells for a mere $250- that doesn't include the sensor modules!
There used to be a video of my system on the American Woodworker website. It got damaged when they changed web hosts and of course a few years ago AWW folded up shop. Unfortunately I somehow lost my original video.
