| 摘要 |
PURPOSE:To control driving circuits of a large number for magnet coil in common, and the reduce the number of parts of the driving circuits by a method wherein an electric power source to be supplied to bases of transistors is controlled. CONSTITUTION:A transistor QA is made in ON condition when a voltage +V1 to be supplied by a resistor R1 exceeds the value to be obtained by adding a Zener voltage VD and a forward voltage VBE between an emitter and a base of the transistor QA, and currents can be supplied to resistors R4-RX. A resistor R2 connected to the base of the transistor QA is a base current limiting resistor for control of a collector current I1 of the transistor QA. A resistor R3 is provided to make reverse leakage currents of bases of transistors Q1-QX to flow through the resistors R4-RX when the transistor QA is in OFF condition. The Zener voltage VD of a Zener diode D1 is selected to the value exceeding a voltage to make it impossble to perform ON, OFF control of outputs corresponding to conditions of inputs A-X because the voltage +V1 to be supplied to digital circuits IC1-ICX becomes low. |
