| 摘要 |
PURPOSE:To prevent the malfunctions due to a defective contact and noises and to improve the reliability of an output voltage program circuit, by securing the connection via diodes among outputs of plural operational amplifiers having different DC voltage amplification factors. CONSTITUTION:The output voltages Va, Vb and Vc of voltage amplifiers consisting of resistances R1 and R2 and an operational amplifier 23, resistances R3 and R4 and an operational amplifier 28, and resistances R5 and R6 and an operational amplifier 33 have different values and connected with each other via diodes 24, 29 and 34 respectively. Then these voltage values are applied to a control circuit 4 in the form of the reference voltage. A logical circuit consisting of inverters 35, 37 and 40 and AND gates 38 and 41 selects three operational amplifiers 23, 28 and 33 by external signals VMH and VML and varies the output voltage of a DC constant voltage source. |
