## Basic Electronic Exercises

### Instructions

- Read every word of the instructions, carefully
- If you get stuck, move on. Another question might help you understand something you are stuck on
- Read every word of each question, very carefully, and be sure to answer all parts. Too often students don’t read the question carefully and either answer the wrong question, or only part of the question
- Write clearly. I do give partial credit for partial work, or for showing you know how to approach a problem, but not if I can’t read it
- Double check your work. I often see simple mistakes that could easily be avoided
- Show all of your work. Use as much extra paper as you wish. I will not give credit for numerical answers that are not accompanied by calculations or explanations. Simple answers to simple questions are fine. Use your common sense
- Always show units when appropriate

### Exercise 1:

a) Explain, in your own words, what determines whether two or more components are connected in series.

b) Explain, in your own words, what determines whether two or more components are connected in parallel.

### Exercise 2:

a) Can the same components be both in series and in parallel?

b) Can the same components be neither in series nor in parallel?

c) Can a circuit contain some components in series, some in parallel, and some neither?

### Exercise 3:

For each figure below, identify which of the components are connected in series with each other, and which of the components are connected in parallel with each other.

### Exercise 4:

For each figure below, identify which of the components are connected in series with each other, and which of the components are connected in parallel with each other.

Figure 1:

Figure 2:

Figure 3:

### Exercise 5:

Calculate the voltage drop on the resistor, the current through the resistor, and the power dissipated in the resistor:

V1 = 9.6V

R1 = 2200 Ohms

### Exercise 6:

What is the equivalent resistance of two resistors in series?

What is the equivalent resistance of three resistors in series?

What is the equivalent resistance of four resistors in series?

### Exercise 7:

What is the equivalent resistance of two resistors in parallel?

What is the equivalent resistance of three resistors in parallel?

What is the equivalent resistance of four resistors in parallel?

### Exercise 8:

Calculate the voltage drop on each resistor, the current through each resistor, and the power dissipated in each resistor:

V1 = 15V

R1 = 10K Ohm

R2 = 10K Ohm

### Exercise 9:

Calculate the voltage drop on each resistor, the current through each resistor, and the power dissipated in each resistor:

V1 = 15V

R1 = 10K Ohm

R2 = 20K Ohm

### Exercise 10:

Calculate the voltage drop on each resistor, the current through each resistor, and the power dissipated in each resistor:

Vbattery = 9V

R1 = 980 Ohms

R2 = 1.2K Ohms

R3 = 560 Ohms

### Exercise 11:

Vbattery = 9V

R1 = 980 Ohms

R2 = 1.2K Ohms

R3 = 560 Ohms

### Exercise 12:

Vbattery = 9V

R1 = 980 Ohms

R2 = 1.2K Ohms

R3 = 560 Ohms

### Exercise 13:

Calculate the voltage drop on each resistor, the current through each resistor, and the power dissipated in each resistor. Assume a supply voltage of 12 Volts between points A and B:

### Exercise 14:

Calculate the voltage drop on resistor R1 and indicate the polarity of the voltage on the resistor:

### Exercise 15:

Calculate the voltage drop on resistor R1 and indicate the polarity of the voltage on the resistor:

### Exercise 16:

Calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor:

### Exercise 17:

Calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor:

### Exercise 18:

Calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor:

### Exercise 19

Calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor with the switch open, as indicated. Next, calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor when the switch is closed.

### Exercise 20:

Given:

Vb1 = 7V

Vb2 = 3V

R1 = 10K Ohm

R2 = 5K Ohm total resistance, and the wiper is in the middle

R3 = 20K Ohm

R4 = 15K Ohm

Calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor with the switch open, as indicated. Next, calculate the voltage drop on each resistor and indicate the polarity of the voltage drop on each resistor when the switch is closed.

### Exercise 21:

Given:

V1 = 9V

V2 = 9V

What is the voltage between points A and B? What is the polarity?

### Exercise 22:

Given:

V1 = 9V

V2 = 9V

What is the voltage between points A and B? What is the polarity?

### Exercise 23:

What is the resistance of the following three resistors whose color bands are:

a) brown-black-red

b) red-red-orange

c) yellow-violet-brown

### Exercise 24:

Given:

V1 = 9V

R1 = 1 K Ohm

R2 = 5.6 K Ohm

R3 = 1.2 K Ohm

R4 = 2.2 K Ohm

R5 = 1K Ohm

R6 = 18K Ohm

What is the voltage at point B relative to the voltage at point A?

### Exercise 25

Given:

R1 = 2.2K Ohm

C1 = 10 uF

R2=10K Ohm

.

a) What is the time constant of C1 and R1, when only switch Sw1 is closed?

b) How long will it take for the capacitor to charge almost to the voltage of the battery?

c) What is the time constant of C1 and R2, when only switch Sw2 is closed?

b) How long will it take for the capacitor to discharge?

### Exercise 26

Given:

Forward voltage on diode = 0.7V

R1 = 10K Ohm

R2 = 12K Ohm

R3 = 980 Ohm

R4 = 1.2K Ohm

R5 = 5.6K Ohm

V1 = 12V

What is the voltage on each resistor?

### Exercise 27

Given:

I1 = 150 mA

I2 = 40 mA

I3 = 200 mA

Calculate the current through resistors R1, R2, R3 and R4

### Exercise 28

Given:

V1 = 9.6V

D1 has a forward drop of 0.7V

D2 has a forward drop of 2V

R1 = 1K Ohm

a) What should R2 be in order to limit the current through LED D2 to 25 mA?

b) What is the current through resistor R1?

### Exercise 29

What colors are the bands on the following resistors?

a) 680 Ohm

b) 10 Ohm

c) 470K Ohm

d) 1M Ohm

e) 1.2M Ohm

### Exercise 30-34

Exercises 30-34 use this circuit:

### Exercise 30:

Given:

- Vin = 10 Vrms
- R1 = 100 Ohm
- R2 = 10K Ohm
- R3 = 4M Ohm

Solve:

- Calculate V1, the voltage drop on resistor R1, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 closed

### Exercise 31:

Given:

- Vin = 10 Vrms
- R1 = 10K Ohm
- R2 = 10K Ohm
- R3 = 4M Ohm

Solve:

- Calculate V1, the voltage drop on resistor R1, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 closed

### Exercise 32:

- What are the differences between Exercise 30 and Exercise 31?
- If you were designing a similar circuit and wanted Vout to be as close as possible to Vin, how would you select R1?

### Exercise 33:

Given:

- Vin = 10 Vrms
- R1 = 100 Ohm
- R2 = 10K Ohm
- R3 = 10K Ohm

Solve:

- Calculate V1, the voltage drop on resistor R1, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 open
- Calculate Vout, the voltage at the “output”, with switch S1 closed

### Exercise 34:

- What are the differences between Exercise 30 and Exercise 33?
- If R3 represents an external device that is to be connected to the rest of the circuit, how should R3 be designed to have as little impact as possible on Vout?

### Exercise 35:

Given:

R1 = 10K Ohm

R2 = 10K Ohm

R3 = 5K Ohm

R4 = 2.2K Ohm

Vb1 = 9.6 V

Vb2 = 7.2V

a) What is the voltage drop on each resistor, and what is the polarity?

b) What is the voltage difference between points A and B, and what is the polarity?

### Exercise 36

Given:

Vb1 = 12V

R1 = 330 Ohm

R2 = 10K Ohm

R3 = 680 Ohm

R4 = 32K Ohm

R5 = 47K Ohm

R6 =22K Ohm

R7 = 470 Ohm

a) What is the voltage drop on each resistor, and what is the polarity?

b) What is the voltage difference between points A and B, and what is the polarity?

### Exercise 37

Given:

Vb1 = 12V

Vb2 = 24V

Vb3 = 6V

R1 = 330 Ohm

R2 = 10K Ohm

R3 = 680 Ohm

R4 = 32K Ohm

R5 = 47K Ohm

R6 =22K Ohm

a) What is the voltage drop on each resistor, and what is the polarity?

b) What is the voltage difference between points A and B, and what is the polarity?

### Exercise 38

Given:

Vb1 = 12V

Vb2 = 24V

Vb3 = 66V

R1 = 680 Ohm

R2 = 470 Ohm

R3 = 330 Ohm

R4 = 32K Ohm

R5 = 47K Ohm

b) What is the voltage difference between points A and B, and what is the polarity?

### Exercise 39:

Given:

Vb1 = 4.5V

Vb2 = 9.6V

Vxy at two arbitrary points **X** and **Y** is defined as the voltage indicated by a multimeter with the red test lead touching point **X** and the black test lead touching point **Y**

a) What is the voltage at point A relative to ground, and what is the polarity?

b) What is the voltage at point B relative to ground, and what is the polarity?

c) What is Vab?

### Exercise 40:

Given:

*R*

_{1}= 2

*K*Ω

*R*

_{2}= 4.7

*K*Ω

*R*

_{3}= 3.2

*K*Ω

*R*

_{4}= 5.1

*K*Ω

What is the resistance between points A and B?

### Exercise 41:

*R*

_{1}= 2

*K*Ω

*R*

_{2}= 4.7

*K*Ω

*R*

_{3}= 3.2

*K*Ω

*R*

_{4}= 5.1

*K*Ω

*Vb*1 = 9.6

*V*

### Exercise 42:

*R*

_{1}= 2

*K*Ω

*R*

_{2}= 4.7

*K*Ω

*R*

_{3}= 3.2

*K*Ω

*Vb*1 = 9.2

*V*

*Vb*2 = 4.5

*V*

### Exercise 43:

*Vin*= 10

*mVrms*

*R*

_{1}= 600Ω

*R*

_{2}= 12

*K*Ω

*V*

_{B}, the voltage at point B relative to ground, is zero

*V*

_{C}, the voltage at point C relative to ground?

### Exercise 44:

*V*

_{b1}= 9

*V*

*R*

_{1}= 600Ω

*R*

_{2}= 100Ω

*R*

_{3}= 900Ω

*R*

_{4}= 300Ω

*D*

_{1}is an LED. Its forward voltage drop

*V*

_{f}= 2

*V*and the current through it is 30 mA.

### Exercise 45:

*V*

_{b1}= 12

*V*

*R*

_{1}= 470Ω

*R*

_{2}= 100Ω

*R*

_{3}= 900Ω

*R*

_{4}= 30Ω

*R*

_{5}= 270Ω

*D*

_{1}is an LED. Its forward voltage drop

*V*

_{f}= 2

*V*and the maximum current it can tolerate is 30 mA.

*Sw*

_{1}is a selector switch that can be in one of 5 positions, A through E. As shown it is in position B. (The labels for positions B, C, and D have been left off for clarity.)

### Exercise 46:

### Exercise 47:

*R*

_{1}is a fixed resistor.

*R*

_{2 }is a photoresistor, a light sensitive resistor. When exposed to light, its resistance decreases.

*V*

_{out}is measured relative to ground.

*R*

_{2 }is exposed to more light, does

*V*

_{out}increase or decrease?

*V*

_{out}= 3V?

### Exercise 48:

Given:

R = 1K Ω

C = .22 uF

a) What type of filter is this?

b) What is the cutoff frequency?

c) What is the reactance of the capacitor at the cutoff frequency? What do you notice about this value?

### Exercise 49:

Given:

R = 4.7K Ω

C = 33 nF

a) What type of filter is this?

b) What is the cutoff frequency?

c) What is the reactance of the capacitor at the cutoff frequency? What do you notice about this value?

### Exercise 50:

Given:

- R1 = R2 = R3 = 10K Ohms
- C1 = 10 uF
- Unless otherwise indicated, voltages are relative to the ground
- The op-amp is an ideal op-amp. That means that:
- It has infinite input resistance
- Since there is no feedback:
- Vout=9V if V+ > V-
- Vout=-9V if V- > V+

- Before the switch is closed, the voltage on the capacitor is zero

a) What is the value of Vout before the switch is closed?

b) When will the value of Vout change?

c) After Vout changes, what will its new value be?

### Exercise 51:

Given: A low pass RC filter

a) Starting with Xc, the reactance of a capacitor; Zc, the impedance of a resistor and capacitor in series; the equation for a voltage divider; and the definition of a 3dB voltage drop; derive the equation for f(-3dB), the frequency at which ththe voltage drops by 3dB.

b) Why is this this equation the same for a high-pass filter?

### Exercise 52:

Given:

- An ideal op-amp (see above)
- Since there is feedback, the output of the op-amp (Vout) will do whatever it needs to do so that the voltage at its inputs are identical

a) Derive the equation for the gain of this circuit. Note that it depends only on the two resistors.

b) Why is this called an inverting amplifier circuit?

### Exercise 53:

Given:

- All resistors = 4.7K Ohm
- C1 = .022 uF
- Vb1 = 7.2V
- Vb2 = 9.6V
- A long time has passed

a) What is the voltage across the capacitor?

### Exercise 54:

Given:

- Vb1 = 12V
- Vb2 = 9V
- Vb3 = 24V
- Vb4 = -24V
- R3 = 10K Ohms
- C1 = 10 uF
- Unless otherwise indicated, voltages are relative to the ground
- The op-amp is an ideal op-amp. That means that:
- It has infinite input resistance
- Since there is no feedback:
- Vout=the positive supply voltage if V+ > V-
- Vout=the negative supply voltage if V- > V+

- Before the switch is closed, the voltage on the capacitor is zero

a) What is the value of Vout before the switch is closed?

b) Select values for R1 and R2 so that after half a second Vout will change

c) After Vout changes, what will its new value be?

### Exercise 55:

Given:

- An ideal op-amp (see above)
- Since there is feedback, the output of the op-amp (Vout) will do whatever it needs so that the voltage at its inputs are identical
- Rf = 100K Ohm
- Rs = 10K Ohm
- Vs = 4Vp-p at 440 Hz, center at zero (i.e. no DC component), sine wave

a) Graph 2 cycles of Vs, starting at zero volts

b) Directly below the graph of Vs, graph the corresponding shape and size of Vout. Indicate the scale of the X and Y axis, indicate the value on the Y axis at the peaks, and indicate the value on the X axis at the zero crossing

### Exercise 56:

Given:

- An ideal op-amp:
- V(inverting) = V(non-inverting)

- Rf = 12K Ohm
- Rs = 1.2K Ohm
- Vs = 4mVp-p at 440 Hz, center at zero (i.e. no DC component), sine wave
- Rout = 10K Ohm
- Wiper of Rout is one quarter of the way up from the ground connection

What is the level, frequency, and shape of Vout?

Solution to exercise 56

### Exercise 57:

Given:

- An ideal op-amp:
- V(inverting) = V(non-inverting)
- Voltage gain=-Rf/Rs

- Vs = 37mVp-p at 3600 Hz
- Rf = 1.2M Ohm
- Rs = 120K Ohm
- R1 = 2.1K Ohm
- C1 = .021 uF

What is the level of Vout? You don’t have to describe the shape.

(Note: Although the output wave is the same shape (sine wave), the RC filter introduces a phase shift and so the output is not simply 180 degrees out of phase with the input wave.)

### Exercise 58:

Given:

- An ideal op-amp:
- V(inverting) = V(non-inverting)
- Voltage gain=-Rf/Rs

- Vs =1mVrms, f=1.2 KHz
- Rf =1M Ohm
- Rs =120K Ohm
- R1 =330 Ohm
- C1 =220 nF
- In general, you can not automatically assume that each stage of a circuit can be analyzed in isolation, as if the stage before and after is not present. However, in this exercise, you are given the fact that the filter and op-amp can be analyzed independently.

- Analyze the effect of the filter
- Calculate the gain of the op-amp
- Take the result of the filter calculation, and apply to it the gain of the op-amp

### Exercise 59:

Given:

- Vs = 1.3mV
- Vbe = 0.7mV
- Rb = 100 Ohm
- Ic, the current flowing in resistor Rc, is 3300 times the current flowing through resistor Rb
- Vdd = 12V
- Rc = 330 Ohm

a) What is the value of Ib, the current flowing in resistor Rb? Hint: Calculate first the voltage drop across resistor Rb.

b) What is the current flowing through resistor Rc? Hint: Use given #4 above and your answer from part a

c) What is the voltage drop on resistor Rc? Hint: The resistor with no name does not matter

d) What is the value of Vout? Hint: How does the capacitor appear to DC?

### Exercise 60:

Given:

- Vbat = 8V
- R1 and R3 are fixed resistors, while R2 is a potentiometer. Vout can be varied by turning the potentiometer up and down, but due to R1 and R3, Vout can never go as high as Vbat or as low as ground

Requirements:

- The maximum current Imax allowed is 500 micro amps (500 uA)
- Vout is desired to be about 2V, with R2 set to the middle of its range.
- Vout is desired to be adjustable +/- 0.2V, in other words, from a minimum of 1.8V to a maximum of 2.2V

a) What is the minimal total resistance of R1, R2, and R3 to meet the maximum current requirement?

b) What is the voltage drop on R2 to meet the requirement of the adjustment of +/- 0.2V?

c) What is the voltage drop on R1 and R3, so that Vout is 1.8V when R2 is turned all the way down, and Vout is 2.2V when R2 is turned all the way up?

d) Choose resistor values for R1, R2, and R3 so that all the requirements are met. Note that there are many answers (actually, an infinite number of answers).

### Exercise 61:

Given:

- In this active filter, the cutoff frequency (fc) is determined by R1, R2, C1, and C2.
- R1 and R2 must always be equal
- C1 and C2 must always be equal
- If R1 =R2 = 10K Ohm and if C1 = C2 = 0.016 uF then fc = 1KHz
- The cutoff frequency can be changed by adjusting either the resistors R1 and R2 or the capacitors C1 and C2.
**Decreasing**the resistor values**increases**the cutoff frequency by the same proportion, e.g., if R1 =R2 = 5K Ohm and if C1 = C2 = 0.016 uF then fc = 2KHz**Decreasing**the capacitor values**increases**the cutoff frequency by the same proportion, e.g., if R1 =R2 = 10K Ohm and if C1 = C2 = 0.008 uF then fc = 2KHz

a) Keeping R1 = R2 = 10K Ohm, calculate the value for the capacitors to make fc = 2KHz

b) Keeping R1 = R2 = 10K Ohm, what would be fc if C1 = C2 = 0.147 uF?

c) Keeping C1 = C2 = 0.147 uF, what would be fc if R1 = R2 = 20K Ohm?

### Exercise 62:

This active filter is the same as exercise 61 above, but capacitors are selected by the selector switch, and the resistors are potentiometers. Ganged switches and potentiometers are used in order to maintain equal resistance and capacitance, as is required by this type of filter: Controls (e.g. switches or potentiometers) connected by dotted lines are “ganged”, that is, physically connected so that they are turned together.

Given:

- Sw1 and Sw2 are “ganged” so that C1 and C10 are selected together, C2 and C9, etc.
- R1 and R3 are “ganged” so that they turn to minimum resistance together, and to maximum resistance together.
- R1 = R3 = 10K Ohm. Note this is a potentiometer.
- R2 = R4 = 10K Ohm
- If the potentiometers R1 and R3 are turned all the way to the
**minimum**value, R1+R2 = 10K Ohm and R3+R4 = 10K Ohm - If the potentiometers R1 and R3 are turned all the way to the
**maximum**value, R1+R2 = 20K Ohm and R3+R4 = 20K Ohm

a) If C4 = C7 = 0.016 uF, what is the cutoff frequency with the potentiometers turned all the way to the minimum value?

b) If C1 = C2 = 0.147 uF, what is the cutoff frequency with the potentiometers turned all the way to the minimum value?

c) If C1 = C2 = 0.147 uF, what is the cutoff frequency with the potentiometers turned all the way to the maximum value?

### Exercise 63:

Assume that you have an unlimited supply of batteries of the following voltages:

- 1.2V
- 1.5V
- 2V

Draw a schematic of how you would provide the following voltages (for example, to circuits requiring these voltages). In all cases assume the return path is a ground:

- A single circuit requiring +2V
- A single circuit requiring +2V and +3V
- Two circuits requiring +2V each
- Two circuits, one requiring +2V and one requiring +3V
- Show
**3**ways of providing +6V - A single circuit requiring +12V and -9V
- A single circuit requiring +7.2V and -4.5V
- A single circuit requiring +7.2V, +2V, +3V, and -15V
- A single circuit requiring +15V, -15V, +7.2V, -7.2V, and -1.5V

### Exercise 64:

Given:

- B1 = 17 V
- B2 = 9.2 V
- B3 = 12 V (pay attention to polarity)
- R1 = 6.8 K Ohm
- R2 = 12 K Ohm
- R3 = 5.6 K Ohm
- R4 = 4.7 K Ohm
- R5 = 3.3 K Ohm

Using superposition, calculate the voltage drop on each resistor and indicate the polarity

### Exercise 65:

Given:

- V1 = 15V
- R1 = 10K Ohm
- R2 = 10K Ohm

Calculate:

- Calculate the equivalent resistance of R1 and R2
- Calculate the current flowing through this equivalent resistance
- Is this current the same current that is flowing through the battery? Why or why not?
- Is it the same as the current flowing in R1 and R2? Why or why not?

### Exercise 66

Given:

- V1 = 15V
- R1 = 10K Ohm
- R2 = 20K Ohm

Calculate:

- Calculate the equivalent resistance of R1 and R2
- Calculate the current flowing through this equivalent resistance
- Is this current the same current that is flowing through the battery? Why or why not?
- Is it the same as the current flowing in R1 and R2? Why or why not?

### Exercise 67:

Given:

- Vbattery = 9V
- R1 = 980 Ohms
- R2 = 1.2K Ohms
- R3 = 560 Ohms

Calculate:

- Calculate the equivalent resistance of R1, R2, and R3
- Calculate the current flowing through this equivalent resistance
- Is this current the same current that is flowing through the battery? Why or why not?
- Is it the same as the current flowing in R1, R2, and R3? Why or why not?

### Exercise 68:

Given:

- Vbattery = 9V
- R1 = 980 Ohms
- R2 = 1.2K Ohms
- R3 = 560 Ohms

Questions:

- What is the voltage on each resistor?
- Knowing the voltage on each resistor, calculate the current through each resistor
- Calculate the sum of the three resistor currents
- Calculate the equivalent resistance of the 3 resistor

### Exercise 69

Questions:

- Calculate the equivalent resistance of R2 and R3
- Calculate the equivalent resistance of R1, R2, and R3

### Exercise 70

- Vbattery = 9V
- R1 = 980 Ohms
- R2 = 1.2K Ohms
- R3 = 560 Ohms

Questions:

- Calculate the equivalent resistance of R2 and R3
- Calculate the equivalent resistance of R1, R2, and R3
- Calculate the current flowing into this equivalent resistance

### Exercise 71

Given:

- S1 is a current supply of 2 A
- R1 = 10 Ohm
- R2 = 10 Ohm
- S2 is a 10 V battery

Calculate:

- What is the voltage drop on R1?
- What is the voltage drop on R2?

### Exercise 72

Given:

- S1 is a current supply of 2 A
- R1 = 1 Ohm
- R2 = 1 Ohm
- R3 = 1 Ohm
- S2 is a 2 V battery

Calculate:

- What is the voltage drop on R1?
- What is the voltage drop on R2?
- What is the voltage drop on R3?

### Exercise 73

(a)

Given:

R1 = 10 Ohms

V1 = 9 V

What is the current?

(b)

Given:

R1 = 5 Ohms

Current = 0.01 Amps (which is 10 milli Amps or 10 mA)

What is the voltage V1?

(c)

Given:

V1 = 25 V

Current = 100 mA

What is the value of R1?

(d)

Given:

V1 = 9.6 V

R1 = 10 Kilo Ohm or 10K Ohm

What is the value of the current?

What is the current?

### Exercise 74

(a)

Given:

R = 5K Ohms

C = .2 uF

f = 160 Hz

Vin = 10V

What is Xc?

What is Vout?

(b)

Given:

R = 5K Ohms

C = .2 uF

f = 1.6 Hz

Vin = 10V

What is Xc?

What is Vout?

(c)

Given:

R = 5K Ohms

C = .2 uF

f = 1.06K Hz

Vin = 10V

What is Xc?

What is Vout?

### Exercise 75

Design a low pass filter with a cutoff frequency of 100 Hz. Provide the schematic and select a suitable resistor and capacitor. The resistor should be at least 980 Ohms.

### Exercise 76

Using a 0.0047 uF capacitor, select a resistor for a high pass filter with a cutoff frequency of 16 K Hz. Provide the schematic and select a suitable resistor.

### Exercise 77

### Part 1:

Given:

A 12V battery is to be used to power a 9V electronic device. Using the voltage divider equation and the information below, calculate R2 so as to deliver the desired 9V:

Vb1 = 12V

R1 = 3 K Ohm

Vout = 9V

### Part 2:

Given:

An electronic device is attached to the voltage divider in part 1. Since the electronic device is essentially a resistor, attaching it at Vout effectively places a resistor (Rint, the internal resistance of the electronic device) in parallel, with R2.

If Rint = 9 K Ohm, what is Vout now?

### Part 3:

Given the situation in part 2, change the value of R1 to restore Vout to 9V.

What should the new value of R1 be in order for Vout to return to 9V?

### Part 4:

What is the power (Wattage) dissipated in R1 and R2 now?

### Exercise 78

### Part 1:

Given:

A 12V battery is to be used to power a 9V electronic device. Using the voltage divider equation and the information below, calculate R2 so as to deliver the desired 9V:

Vb1 = 12V

R1 = 30 Ohm

Vout = 9V

### Part 2:

Given:

An electronic device is attached to the voltage divider in part 1. Since the electronic device is essentially a resistor, attaching it at Vout effectively places a resistor (Rint, the internal resistance of the electronic device) in parallel, with R2.

If Rint = 9 K Ohm, what is Vout now?

### Part 3:

What is the power (Wattage) dissipated in R1 and R2 now?

### Exercise 79

Design a voltage divider for a vacuum tube amplifier. Assume that you start with a 400 V battery. You need to generate 6V, 220V, 330V, and 400V.

Part 1: Select resistors to generate these voltages and draw the schematic

Part 2: Calculate the power dissipated in each resistor

### Exercise 80

Given:

V2 = 12V (the voltage on resistor R2)

What is Vb, V1, and V3?

### Exercise 81

Given:

I1 = 0.6mA (the current through resistor R1)

I2 = 1.2mA (the current through resistor R2)

R2 = 10K Ohm

R3 = 15K Ohm

1) Calculate V2

2) What is Vb, V1, and V3?

3) Calculate I3

4) Calculate R1

### Exercise 82

Given:

I2 = 125mA (the current though resistor R2)

What is I1 and I3?

### Exercise 83

Given:

V1 = 4V (the voltage on resistor R1)

V2 = 3V (the voltage on resistor R2)

R2 = 10K Ohm

R3 = 15K Ohm

1) Calculate I2

2) What is I1 and I3?

3) Calculate R1

4) Calculate V3

5) Calculate Vb

### Exercise 84

Given:

I3 = 2mA (the current through resistor R3)

R1 = 4.7K Ohm

R2 = 10K Ohm

R3 = 15K Ohm

1) Calculate V3

2) What is V2?

3) Calculate I2

4) Calculate I1

5) Calculate V1

6) Calculate Vb

### Exercise 85

Given:

I2 = 0.5mA

I5 = 0.2mA

R1 = 4.7K Ohm

R2 = 10K Ohm

R3 = 15K Ohm

R4 = 6.8K Ohm

R5 = 2200 Ohm

R7 = 10K Ohm

- Calculate V2
- What is V3?
- Calculate I3
- Calculate I1
- Calculate V1
- What is I4?
- Calculate V4
- Calculate V5
- What is I7?
- Calculate V7
- What is V6?
- Calculate I6
- Calculate R6
- Calculate the battery voltage Vb

### Exercise 86

Given:

I4 = 2 mA

I6 = 0.5 mA

R1 = 1 K Ohm

R2 = 3 K Ohm

R3 = 3 K Ohm

R4 = 1 K Ohm

R5 = 5 K Ohm

R6 = 15 K Ohm

R7 = 2 K Ohm

- What is the voltage drop on each resistor?
- What is the voltage of the battery?

### Exercise 87

Given:

Vb = 12V

R1 = 10 K Ohm

R2 = 10 K Ohm

- What is the voltage drop on R1 and R2?
- Explain how you came to this conclusion

### Exercise 88

Given:

Vb = 12V

R1 = 10 K Ohm

R2 = 10 K Ohm

R3 = 10 K Ohm

- What is the voltage drop on R1, R2, and R3?
- Explain how you came to this conclusion

### Exercise 89

Given:

V5 = 2 V

R1 = 3 K Ohm

R2 = 10 K Ohm

R3 = 20 K Ohm

R4 = 10 K Ohm

R5 = 5 K Ohm

- What is the voltage drop on each resistor?
- What is the voltage of the battery?

May 1, 2011 at 10:05 am |

Gees, they started kinda easy then they got “kinda hard”. 🙂

October 31, 2011 at 10:17 pm |

^says the science guy

July 7, 2013 at 2:59 pm |

Where are the answers for these exercises? I am a beginner, and like to learn the basic of electronic. Where can I learn online?Thanks

July 9, 2013 at 2:50 am |

Hi Charles,

Thanks for your interest. I’m afraid I have not yet had time to put answers on the page. I hope to, one day…

A great resource for learning, as well as exercises with answers is All About Circuits.

You could also try googling with keywords “electronics” and “tutorials”. There are many.

March 27, 2017 at 2:17 am |

Perfect. but Where is the answer?

March 31, 2017 at 3:16 pm

I don’t provide answers. This is meant as a pool of questions.