TM 31-210
Improvised Munitions Handbook
| Section VII |
No. 4 |
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METAL BALL SWITCH |
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| This switch will close an electric circuit when it is tipped in any direction. It can be used alone for booby traps or in combinations with another switch or timer as an anti-disturbance switch. | |
| MATERIALS REQUIRED: | |
| Metal Ball 1/2" (1 1/4 cm) diameter (see Note) |
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| Solid copper wire 1/16" (1/4 cm) diameter | |
| Wood block 1" (21/2 cm) square by 1/4" thick | |
| Hand drill | |
| Connecting wires | |
| Soldering iron & solder | |
| NOTE: If other that a 1/2" diameter ball is used, other dimensions must be changed so that the ball will rest in the center hole of the block without touching either of the wires. | |
| PROCEDURE: | |
| 1. Drill four 1/16" holes and one 1/8" hole through the wood block as shown. |
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| 2. Form two "U" shaped pieces from 1/16" copper wire to the dimensions shown. |
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| 3. Wrap a connecting wire around one leg of each "U" at least 1/4" from the end and solder in place. |
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| 4. Place metal ball on block so that it rests in the center hole. |
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| 5. Insert the ends of the small "U" into two holes in the block. Insert large "U" into the remaining two holes. |
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| CAUTION: Make sure that the metal ball does not touch either "U" shaped wire when the switch is standing on its base. If the ball does touch, bend wires outward slightly. |
| HOW TO USE: | |
| Mount switch vertically and connect in electrical firing circuit as with any other switch. When tipped in any direction it will close the circuit. | |
| CAUTION: Switch must be mounted vertically and not disturbed while completing connections. |
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