| 摘要 |
PURPOSE:To diversify magnetic field patterns by such an arrangement wherein when a thyristor is ignition-controlled by subdividing the period of an AC power source, a counter in which the number of ignition signal is to be set and another counter in which the number of cycle whereby the conduction of a current into a coil is suspended is to be set are provided. CONSTITUTION:A clock generator 1 is set so that it subdivides a half period of a commercial power source, and a preset counter 2 is controlled through a monostable multi vibrator 4 and a pulse form shaping circuit 5, and the firing angle of a thyristor is controlled through an NAND gate 3 by a specified number of pulse given by a binary counter 7. Further, a preset counter 11 which is capable of presetting the number of ignition signal of the same phase angle to be generated and another preset counter 12 which is capable of presetting the number of half period for suspending the conduction of a current to a coil are provided and an FF13 is also provided to control the counters 11, 12. By this arrangement, demagnetization can be performed by causing ignition of the same flow angle to take place at a desired number of time and by setting the suspension period of the thyristor to a desired number of half period in response to the build up time of an AC magnetic field. |
