1985 - Volume #9, Issue #4, Page #31[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
Automatic Draperies Bluff Burglars
The draperies open in the morning, close in the evening. And, as a bonus, the system also turns on a table lamp.
As shown in the drawings, the main components of the system are two lamp timers and a 100/100-hp, 25- or 30-rpm reversible motor. All are in a box mounted on the wall next to the drapes. The timers are set to open or close the drapes at a specific time by controlling the direction of the motor. The motor turns a bicycle sprocket that pulls a chain attached to the pull cords of the drapes.
To get the correct speed, the sprocket should be 7¢ in. in dia. if a 25-rpm motor is used; 5¢ in. for a 30-rpm motor. The length of the chain depends on the sprocket size and traverse distance: Make it six inches longer than half the circumference of the sprocket, plus the distance needed to fully open the drapes. Form two 1-in. pieces of clothes hanger into L shapes and solder them to the chain. (File away the anodized coating on the hanger wire and chain so the solder will adhere.) Position them so that the first piece trips the toggle limit switch down when the draperies are open (see drawing) and the second flips the switch up when they are closed.
All components mount inside an eight-by eight-by five-inch enclosure. Wire them according to the diagram. The double-pole double-throw toggle switch selects automatic or manual mode. In the manual mode, the draperies can be opened or closed by pressing one of the two exterior push buttons. Before mounting the enclosure, close the draperies and cut the opening pull cord at about 14 in. from the rod. Install the chain at its closed position, and fasten its long end to the cord. Finally, mount the box so the chain is taut; cut the second draw cord, and attach it to the short end of the chain.
Most of the components are available through a local electronics store, such as Radio Shack. The sprocket and chain can be found in any bicycle shop. And the motor (I used a Dayton 27814; $38) can usually be bought through an electrical-supply dealer. The total price of my system, including the motor, was $85.
(Reprinted from Popular Science with permission. Copyright, 1985, Times Mirror magazines, inc.)
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