| 摘要 |
<p>1278390 Cinematographic projectors GAF CORP 15 Dec 1970 [29 Dec 1969] 59450/70 Heading G2E [Also in Division H2] A motion picture projector Fig.1 (not shown) of the kind having an electric motor 24 arranged to drive a take-up reel (22), the motor having a winding 42 connectable to a source 46, of A.C. current, is further provided with a single pole double throw switch 52 for altering the number of effective turns in the winding 42 thereby maintaining the impedance of the winding substantially constant. The projector may thus be used with e.g. both a 60 hertz and a 50 hertz power supply. The switch 52 is operable to connect one of two taps 58, 60 with the source 46.</p> |
