| 摘要 |
A driver circuit to drive an M-lead in a tie trunk between telephone branch exchanges is disclosed. The driver continues to provide for a current increase as the resistance of the load on the M-lead decreases, until at a particular point maximum current is achieved. After this point, as the resistance of the load continues to decrease, the driver circuit decreases the load current, such that power dissipation in the driver is kept at a safe level for a device. The V-I characteristic of the driver circuit is such that for any given value of load resistance, the circuit has only one possible point of operation which will eliminate any possibility of latch-up. Simplicity and precision are also achieved by this circuit. The accuracy of the performance characteristic is limited only by the tolerance of the passive components used.
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