| 摘要 |
PURPOSE:To simplify a circuit and save power, by discriminating feedback signal level on the basis of threshold voltage. CONSTITUTION:When a transistor 12 turns ON, gate trigger current goes from VDD of a DC stabilizing power source 2 to VSS passing through an AC passage's common line, a terminal T1 of an AC control element 14, a gate G, the transistor 12 and a control resistor 15 of gate current, and then, terminals T1 and T2 of the AC control element 14 are conducted. While base of the transistor 12 is being pulled up to VDD, the transistor 12 is in OFF position. And therefore, in case if a voltage to be put into an EX-NOR gate 5 from a contact between a sensor 7 and a variable resistor 8 is lower than the threshold voltage, a DC motion element 6 is fed with positive half-wave of sine wave pulse, and if the voltage is higher than the threshold voltage, the element 6 is fed with negative half-wave of sine wave pulse supplied directly from an AC passage. |
