| 摘要 |
PURPOSE:To prevent a case where two output lines are set at high levels simultaneously with the output is supplied to three output lines, by using a switching transistor and a diode to detect the levels of two input lines. CONSTITUTION:The input 1 of I1 and I2 are set at levels L, both transistors TR6 and 7 are turned of. At the same time, a base current of a TR19 flows via a resistance 15, a diode 16 and a resistance 17. Thus the TR19 is truned on and therefore the cathode terminals of diodes 20 and 21 are also set at levels L. Then O2 and O3 of an output 2 are set at levels L, and only O1 of the output 2 is set at a level H. In such a way, either one of three output lines is set at a level H.
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