| 摘要 |
PURPOSE:To improve the stability and responsiveness by connecting an N gate and an SCR gate with a capacitor, which is operative to hold the voltage, thereby to control the discharge rate of the capacitor. CONSTITUTION:The writing signals amplified by a high gain amplifier 3 charge a capacitor CM along a charging path, which is composed of the capacitor Cm, a programmable unijunction transisor PUT having an N gate SCR and a gate G, an anode A and a resistor Rc. In this instance, the PN junction of the gate G and anode A of the transistor PUT is biased in the forward direction so that the capacitor CM is charged to a satisfactory extent in excellent response through the transistor PUT which is operative to effect the contactless switching operation with a time constant according to the connection between the capacitance CM and the resistor Rc. The charged voltage thus held leaks to be discharged from between the gate G and cathode K of the transistor PUT to allow no discharge current. As a result, if the transistor PUT is selected, the discharge rate is controlled to reduce the leak current so that the desired voltage is held stably for a long time. |
