Holooly Plus Logo
Holooly Plus Logo

Question 5.4: What does the circuit of Fig. 5-7 do?

What does the circuit of Fig. 5-7 do?

5.7
The blue check mark means that this solution has been answered and checked by an expert. This guarantees that the final answer is accurate.
Learn more on how we answer questions.

This is an example of a preregulator (the first zener diode) driving a zener regulator (the second zener diode). First, notice that the preregulator has an output voltage of 20 V. This is the input to the second zener regulator, whose output is 10 V. The basic idea is to provide the second regulator with a well-regulated input so that the final output is extremely well regulated.

Related Answered Questions

Question: 5.13

Figure 5-22b is a continuity tester. After you turn off all the power in a circuit under test, you can use this circuit to check for the continuity of cables, connectors, and switches. How much LED current is there if the series resistance is 470 Ω? ...

Verified Answer:

When the input terminals are shorted (continuity),...
Question: 5.5

What does the circuit of Fig. 5-8 do? ...

Verified Answer:

In most applications, zener diodes are used in vol...
Question: 5.9

The zener regulator of Fig. 5-13 has VZ = 10 V, R2 = 270 Ω, and RZ = 8.5 Ω, the same values used in Application Examples 5-7 and 5-8. Describe the measurements being made in this Multisim circuit analysis. ...

Verified Answer:

If we calculate the voltages in Fig. 5-13 using th...
Question: 5.6

Briefly describe the circuit action for each of the circuits in Fig. 5-9. ...

Verified Answer:

Figure 5-9a shows how zener diodes and ordinary si...
Question: 5.18

What does the circuit of Fig. 5-39a do? ...

Verified Answer:

A transistor is a semiconductor device that acts l...
Question: 5.17

What does the system shown in Figure 5-31 do? ...

Verified Answer:

Figure 5-31 shows the block diagram of a light det...
Question: 5.16

What does the circuit of Fig. 5-25 do? ...

Verified Answer:

This is a blown-fuse indicator. If the fuse is OK,...
Question: 5.15

The circuit of Fig. 5-24 shows an LED indicator for the ac power line. The idea is basically the same as in Fig. 5-23, except that we use a capacitor instead of a resistor. If the capacitance is 0.68 μF, what is the average LED current? ...

Verified Answer:

Calculate the capacitive reactance: X_C=\fr...
Question: 5.14

LEDs are often used to indicate the existence of ac voltages. Figure 5-23 shows an ac voltage source driving an LED indicator. When there is ac voltage, there is LED current on the positive half-cycles. On the negative half-cycles, the rectifier diode turns on and protects the LED ...

Verified Answer:

The LED current is a rectified half-wave signal. T...
Question: 5.12

Figure 5-22a shows a voltage-polarity tester. It can be used to test a dc voltage of unknown polarity. When the dc voltage is positive, the green LED lights up. When the dc voltage is negative, the red LED lights up. What is the approximate LED current if the dc input voltage is 50 V ...

Verified Answer:

We will use a forward voltage of approximately 2 V...