E6C07 — Amateur Extra Class

E6C07 : What best describes a pull-up or pull-down resistor?
A A resistor in a keying circuit used to reduce key clicks
B A resistor connected to the positive or negative supply used to establish a voltage when an input or output is an open circuit
C A resistor that ensures that an oscillator frequency does not drift
D A resistor connected to an op-amp output that prevents signals from exceeding the power supply voltage
Correct Answer: A resistor connected to the positive or negative supply used to establish a voltage when an input or output is an open circuit