CURRENT SUPPLY CIRCUIT FOR TELEPHONE SWITCHBOARD

摘要

PURPOSE:To prevent unneeded heating with electric power consumption lessened by limiting a current supply to a subscriber, by limiting the maximum value of the output current of a current-supplying current amplifier by the use of a Zener diode. CONSTITUTION:Output currents of current-supplying current amplifiers 1 and 1' are limited by Zener diode ZD1 and then supplied to output voltage detector 3 and a load (e.g., subscriber's line) between terminal 5 and 5' by way of driving current amplifiers 2 and 2'. Therefore, even a loop with small load resistance can prevent a needed current or more from flowing.