Question

1.Will an oscilloscope interfere with a circuit under test? Justify your answer.

2.For a dual power supply, show the necessary connection to obtain -5V and -8V with respect to a common (chassis) ground. Repeat for -5V and +8V.

3.Explain the use of the current limiting feature for the dual-voltage power supply.

4.What happens to the output current and voltage when the power supply is shorted?

5.Explain the function of the AC/DC selector on the DMM.

Answer 1

1.

Will an oscilloscope interfere with a circuit under test?

It depends. The oscilloscope probe is associated with a resistance and a capacitance value. A switch in probe compensates for this. On x1 it will generally show 1 MegOhm resistance and around 20 pF capacitance. Such capacitance is a problem when used on rf circuits. Using x10, the probe will show about 10 times lesser capacitance and an input resistance of 10 Mhohms. and the probe will not affect the parameters of the circuit.

2.

3.Explain the use of the current limiting feature for the dual-voltage power supply.

The current-limitting feature for the dual-voltage power supply limits the amount of current that can be drawn from the supply. It is nequired in case someone accidently shorts the ground to the positive terminal.

4. .What happens to the output current and voltage when the power supply is shorted?

When a power supply is shorted it tries to draw an infinite amount of current as R=0, the voltage gets very low The voltage will be zero when a supply is shorted.As a result, the power supply will quickly burn up.

5.Explain the function of the AC/DC selector on the DMM.

When AC is selected, a capacitor is put at the input of the meter to block any dc. O

When DC is selected, there is no capacitor at the input to block it .The dc bias voltage will also be recorded .