| 摘要 |
PURPOSE:To obtain a small-sized inexpensive circuit by constituting a simple stabilizing power supply with a 1st transistor(TR) and a Zener diode or the like to allow a 2nd TR to act like a comparator. CONSTITUTION:An AC voltage is rectified by a diode bridge 12 and a pulse current takes place at a point A. Moreover, when the level of the pulsating current is smaller than a Zener voltage (=Vz), the pulsating waveform is supplied to the base of a TR 3 and when the pulsating waveform is larger the voltage Vz, the voltage Vz is applied to the base of the TR 3 respectively. As a result, a capacitor 5 is charged to the voltage Vz. When the level of the pulsating current is smaller than the voltage Vz, a TR 6 is energized and a power zero cross pulse ZVP is caused in the collector. On the other hand, the TR 3 is cut off. When the level of the pulsating current is larger than the Vz, the TR 6 is cut off and the ZVP appearing at the collector disappears. On the other hand, the TR 3 is conductive to supplement the charge lost in the capacitor 5. In the series of operations as above, since no comparator IC is employed, the constitution is simplified. |
