When John Dawson turns on his table saw
he wants a Shop-Vac®
to automatically turn on, too. He might have controlled a duplex outlet
from a wall switch, but where's the fun in that? Instead, he uses a Hall-Effect
sensor to detect current flow in the saw's power cord and then turn on the
vacuum cleaner via a relay. John's design adapts well to other control
situations, too. Don't get sucked into a simple switch circuit.
California’s plan to mandate an electric vehicle market isn’t the first such undertaking and certainly won’t be the last. But as the Golden State ratchets up for its next big step toward zero-emission vehicle status in 2018, it might be wise to consider a bit of history.