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FOUR_POSITION_MOTOR_SWITCH

2016-09-02 17:37  
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FOUR_POSITION_MOTOR_SWITCH
Single RF feed line also carries DC for 3-V permanent magnet DC motor B1 atop antenna tower, driving S3 and S4 for remote switching to antennas a, b, c, and d. Diagram shows switches set for feed to antenna a, with no drive applied to Bt since cam C has opened microswitch S5. CR5 and CR6 are now connected in series with opposite polarity, so neither positive nor negative halfwaves from 12-VAC supply can drive motor. If S2 is closed, poshive halfwaves start B1. Once started, motor runs until cam opens S5; if S2 has not yet been released, motor continues running on positive and negative halfwaves. Diode bridge CR1-CR4 makes motor rotate in only one direction for either drive polarity. If S2 is released, before S5 opens, motor stops. 6-V 1-A lamp DS1 comes on dimly when S2 is closed and brightens when S5 closes. If S2 is released now, B1 drives to next position and stops. If S2 is held down, switching continues. Meter M1 and CR7 identify position of switch. R1-R4 in range of 1K to 10K, are chosen to give 1/4, 1/2, 3/4, and full deflection of meter. Motor drives switch through 2860:1 reduction gears taken from alarm clock. All diodes are 50-PIV 1-A silicon such as 1N4001.-U.H.Lammers, A Remote Antenna Switch, QST,Aug.1974, p 41-43.