| 摘要 |
<p>PURPOSE:To establish the start signal generation circuit having greater reliability with low cost and small sized constitution, by adding the CR time constant circuit and relay circuit to the voltage comparison detecting whether DC output voltage reaches the specified value or not. CONSTITUTION:When the DC output voltage E is more the that specified value, the output S' of the voltage comparison circuit 41 is inverted from logic 1 to 0 and logic 1 via the NOR circuit 61, but is clampled at the ground level of logic 0 for a given time with the contact 51. The output S' of the circuit 41 is inverted for the level with the NOR circuit 62, turns on the charging up transistor Tr35 and the capacitor 32 through the resistor R33, contact 31a. When the charging is finished, the relay 21 is operated and the contact 51 is opened and the normal start signal S of logic 1 is delivered. Simultaneously, C32 is rapidly discharged through R34 with the contact 31b. When the voltage is less than the specified voltage with the input power supply cut off, the output S' of the circuit 41 changes from logic 0 to 1, it is 0 with the circuit 61, informing ineffective signal S. Accordingly, the signal S is not effected with the chattering of the contact 51 and high reliability signal can be obtained.</p> |
