197. If a certain circuit has a current that is lagging the voltage by 45˚, then it displays

Find the voltage difference between a and b using the node voltage method:

   2. Consider the following circuit (18 pts): 

2A) Use the node voltage method to find the voltage difference between nodes A and B for t<0 s. (3 pts)

Question 3  (IEIIQ16)

A 3 W rated Zener diode is used in a shunt voltage regulator circuit to supply a dc output of 12 V to a variable load with a minimum resistance of 240 Ω. The supply voltage varies between 20 V and 24 V.

3.1    Draw the circuit diagram.

3.2    Calculate the range of series resistance that may safely be used in this circuit. Select a single suitable standard value.

3.3    Calculate the maximum power rating required for the series resistor.

Question 4  (IEIIQ17)

A simple Zener voltage regulator is required to provide a steady regulated output voltage of 10 V under a maximum load of 80 mA, while the input voltage to the regulator varies between 12 V and 14 V.

17.1  Calculate the maximum rated current value of a Zener diode to be used

17.2  Calculate the minimum power for the Zener that could be used safely.

17.3  If a 5 W rated Zener were to be used in this circuit:

(i)      Calculate the maximum rated current value of a Zener device to be used

(ii)      Calculate the range of possible RS.  limiting resistor values.

(iii)     Suggest a suitable standard E12 resistor value

Question 1

A simple Zener diode shunt voltage regulator is to supply 12 V to a load which normally draws a load current which varies from 0 to 50 mA. The input voltage varies between 15 V and 18 V.

1.1 Calculate the maximum rated current value of a Zener device to be used.

1.2 Calculate the minimum power for the Zener that could be used safely.

1.3 If a 5 W rated Zener were to be used, calculate the range of possible RS. values and hence suggest a suitable standard E12 resistor value.

1.4 State four (4) conditions under which a Zener diode dissipates minimum power in a regulator circuit.

Question 2 (IEIIQ15)

A 2.5 W Zener diode is used in a simple Zener shunt voltage-regulator to supply 5.1 V to a load which normally draws a load current varying from 0 to 125 mA. The input voltage varies between 8 V and 9.5 V

2.1 Give two (2) reasons for the inclusion of the series resistor in the Zener-regulator circuit.

2.2 Calculate the range of series resistance that may safely be used in this circuit.

2.3 Select a single suitable standard E12 resistor value and give its colour code with 1 % tolerance.