Author: John Grout
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Airport Luggage Cart (or Lawnmower): Don’t Roll Away!
This airport luggage cart has brakes which are applied whenever the yellow handle is not depressed. Carts will not roll unless they are attended to. When carts nested, the rear wheels of all but the last cart are wedged off the floor, so the carts can be pushed easily by airport staff returning them to…
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Don’t Leave the Lights On at the Hotel
In China, where electric power has been scarce, hotel rooms are equipped with a room key holder that turns off the power when the key is removed. This ensures no electricity flows to the room while it is vacant. This is now common in other countries too.
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A Drill That Stops Automatically
The manufacturer has rigged this drill to stop immediately when the bit contacts any grounded or electrically live materials, so you can’t drill through hidden pipes or wiring.
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Credit Card Missing from Wallet
The manufacturer has rigged these wallets to sound an audible beep when a card is absent from the wallet. While this device would clearly be annoying to some users, for others it would be a big help in remember to replace credit cards after use.
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Automatic Stove Top Shut Off
This type of stove burner turns off automatically when pot or pan is removed.
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Keeping Pool Water Levels at the Right Level
This device continuously monitors the water level. If the level is too low, a valve opens to add water to the pool.
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Shoplifting Prevention
Retail stores and libraries use “electronic article surveillance” systems to prevent the removal of merchandise and books that have not been paid for or checked out.
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Smoke Detectors
Many smoke detectors are designed so they cannot be mounted on the wall until a battery is installed.
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Brake Systems
Some brake systems utilize permanent magnets to generate power-off braking force. Current supplied to magnetic coils counter permanent magnetic force to keep the brakes from engaging during normal operation.
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Elevator Doors
Many Elevators are equipped with an electric eye to prevent doors from shutting on people. They also are equipped with sensors and alarms to prevent operation when overloaded.