Case #98: Bob Solved His Chip Problem

February 26, 2007

Woodworker Bob Neidorff bought a vacuum to collect the chips and sawdust from his shop equipment, and plumbed it to the vacuum ports on his power tools and to his homemade vacuum hose ports. But then, he had to turn it on and off every time he used a machine. That is, until he built this gadget. A torroidal power transformer and a handful of electronics detects the load current of the machines involved and controls the vacuum automatically. Now whenever the chips are flying, they're heading for the vac.

"Vacuuming the Shop"
Amount Part Description Allied Part #
1 Toroidal power transformer, 117V to 12VCT (Hammond 182L6) 836-0814
1 Bridge rectifier, greater than or equal to 500 mA, greater than or equal to25V (Semikron S380) 550-6006
1 Capacitor, 470 uF, greater than or equal to 10V (Illinois Capacitor 477CKS010M) 613-0089
1 Resistor, 49.9 ohms, greater than or equal to 1/8W (Dale RN55D49R9F) 895-0962
1 NPN Transistor, 2N3904 (TO-92); or NPN Darlington, TIP122G (see text) 568-0292 568-0402
1 Solid-state Relay, 400V, 120 mA (Panasonic AQV214EH) 788-1253
1 Transorb, 400V (Littlefuse 1.5KE400CA) 846-0729
1 Contactor, 30 amp, 2 pole (Stancor 122-903) 576-3006
1 Toggle switch, Single Pole, 5A, 250V, Carling DA100-PB-B or use common light switch 683-0085
Additional parts required
4" PVC drain pipe and fittings, from a local lumberyard or hardware store
Download the Build Instructions

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