Control circuits in use
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Flip to reveal answersWhat does a decoupling capacitor do?
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Question
What does a decoupling capacitor do?
Answer
A 100 nF capacitor beside the supply pins supplies the brief surge when an output switches, so the rail does not dip and reset the chip.
Question
Why does a switch need a pull-up resistor?
Answer
A switch alone connects the pin to 0 V when pressed and to nothing when released. The pull-up gives it a defined level the rest of the time.
Question
What is debouncing?
Answer
Reading a mechanical switch twice a few milliseconds apart, because it bounces on contact and one press would otherwise look like several.
Question
Why give a motor its own supply rail?
Answer
A motor draws several times its running current at start-up. Sharing a rail with the chip drags the supply down and resets it as the motor switches on.
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Topic 7.4 hub
Electronic systems applied
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