Does any one know how to build one of these? * Plugs directly into any standard 15Amp/125 VAC standard house outlet. * Powers a 15Amp rated/125 VAC Wet/Dry Vacuum, Dust Collectors (max. 1.5 HP) or Power Feed. * Works with any 15Amp rated/125 VAC Miter saw, Table saw, Router, Planner, Sander..... * Input connection: 3-Prong (grounded) male. * Tool outlet connections: Will except 2/3-prong plugs. * Dimensions: 2" x 4" x 3" * Black textured finish. * Made of durable UL-rated 94V, ABS plastic. * Onboard "Atmel" Microcontroller, controls the inrush of current during start-up to help eliminate overload and provides a 7-second timed delay off to clean out the inlet pipe. http://dgcproducts.com/index.html
I think making one would be pretty expensive and time consuming, and wouldn't be worth the trouble. Maybe using a powerbar so that you have to switch the powerbar on when you want to use the saw, and it will turn on the vacuum for you? Or maybe a sticker on the saw that says "TURN ON VACUUM!" or something. Making one of those things with the features that has would be extremely difficult for an experienced person, and impossible for a novice. Thats just my 2p worth though.
How about a coil wrapped around the wire of the saw, amplify the output with an op amp and use it to reset a monostable with a time period of 7 seconds that switches a relay. You hit the trigger, current flows in the wire (which could be the wire to a 4way block or something) inducing a small current in your coil that is amplified, triggers the monostable turning on the relay. When you come off the trigger the current stops flowing so there is no voltage to reset the monostable so 7 seconds later the relay turns off. Sometimes a microcontroller just makes things more complicated. I havent got any time atm but ill do a diagram to explain better when i get back from college. Moriquendi
How about using a capacitor? Splitting the cord in two; one for the machine operated and other to capacitor->vacuum. Might need quite a large cap to run it for seven seconds though.... I have little to no knowledge about electronics, so don't laugh is this is beyond stupidity
With a DC, low power circuit that would work but capacitors have a very different effect on AC circuits and even if it did work in the same way you would need a capacitor the size of your house to supply a vac for 7 seconds. I have a schem of a circuit i reckon would do what you want (apart from controlling inrush current) How do i post an image? Moriquendi