| 摘要 |
PURPOSE:To obtain a hysteresis circuit which does not injure an external device by providing an operational amplifier which compares the input signal voltage with the comparison reference voltage, a transistor circuit which has a switching action with the output voltage of the operational amplifier and a circuit which feeds the working current of the transistor circuit back to a comparison reference voltage generating circuit. CONSTITUTION:If VIN<VY1 is satisfied between the input signal voltage VIN and the input voltage VY1 of a positive input terminal, a transistor Tr1 is turned off and a current If flowing through a feedback resistance Rf is equal to 0. Thus VY1=a.VX1=a(V+-RX.IX) is satisfied. Then the voltage VIN increases and VIN=VY1 is satisfied at a time point t1. Thus the Tr1 is turned on. Here VY2=a.VX2=a{V+-RX(IX+If)} is satisfied for the input voltage VY2 of the positive terminal. Then the voltage VIN increases and then reduced again at a time point t2. Thus the Tr1 is turned off again at a time point t3 when VIN =VY2 is satisfied.
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