Switching control circuits for electronic calculator with push-button on-off system

摘要

An electronic calculator with a power supply ON-OFF arrangement actuated by momentary-closure push-button switches which are part of the keyboard. A bistable latch circuit on the calculator chip is continuously powered by the battery, and is caused to flip to an ON condition by actuating an ON key, and this turns on an oscillator, the output of which is pumped up to a level above the battery, and the high level voltage is used to drive a large, low-resistance transistor. This transistor is in series with the voltage supply line going to all of the other electronic circuitry on the chip. The oscillator and pump circuit assure that the drop across the transistor is negligible.