Laboratory 1: Series Circuit

Series circuits are characterized by the fact that they contain only one path for current flow. There are three rules concerning series circuits that, when used with Ohm’s law, permit values of current, voltage, and resistance to be determined.

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

The simplest way to go about this is to acquire all the resistors we need and then place them. Click on the resistor icon 3 times so that you have 3 resistors sitting in the top left corner of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen

Now just arrange the resistors as they are in figure, To connect the "wires", simply click on the nodes of the resistors you would like to join.

Resistor R1 has a value of 20 Ω, R2 has a value of 12 Ω, and resistor R3 has a value of 16 Ω. The battery has a terminal voltage of 24 volts. Since current must pass through each of these resistors, each hinders the flow of current. The total amount of hindrance to current flow is the combined ohmic value of each resistor. The second rule of series circuits states that the total resistance is the sum of the individual resistances. The total circuit resistance can be determined by adding the values of all the resistors. To use the ohmmeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Calculate the total circuit resistance of the circuit

RT = _______________ Ω

Use the ohmmeter to determine the total resistance of the circuit

RT = _______________ Ω

Press the play button on the bottom left of the screen to activate the power source. Notice that information about the circuit will be displaced at important locations (such as the resistors). Every Circuit does not have a multimeter as a whole but it has it in parts. You can find along the parts menu a voltmeter, ampere meter and an ohmmeter. To use the multimeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Using an voltmeter, measure the amount of voltage drop across each of the resistor.

R1 = _________ V

R2 = _________ V

R3= _________ V

Add the voltage drop across each resistor. Compare the sum with the applied voltage of the circuit.

(E1 + E2 + E3 ) _______________ volts

Notice that if all the voltage (pressure) drops are added, they will equal the applied voltage of the circuit. The third rule of series circuits states that the total voltage is equal to the sum of the voltage drops around the circuit.

Calculate the total circuit current using the total circuit voltage and total resistance. Compare this calculated value with the measured value.

IT = _______________ amp(s)

Turn on the 24 volt power supply and measure the current flow in the circuit.

I = _______________ amp(s)

Laboratory 2: Parallel Circuit

Parallel circuits are characterized by the fact that they have more than one path for current flow. There are three rules concerning parallel circuits that, when used in conjunction with Ohm’s law, permit values of voltage, current, and resistance to be determined for almost any parallel circuit. As with series circuits, the total power consumption of the circuit is the sum of the power consumption of each component of the circuit.

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

The simplest way to go about this is to acquire all the resistors we need and then place them. Click on the resistor icon 3 times so that you have 3 resistors sitting in the top left corner of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen

Now just arrange the resistors as they are in figure, To connect the "wires", simply click on the nodes of the resistors you would like to join.

Resistor R1 has a value of 240 Ω, R2 has a value of 80Ω, and resistor R3 has a value of 60 Ω. The battery has a terminal voltage of 120 volts. Notice that each branch is connected directly to the power source. If a voltmeter were connected across each branch, it would be seen that the source voltage is applied across each branch. The first rule for parallel circuits states that the total current is the sum of the currents through each branch of the circuit.The second rule for parallel circuits states that the voltage is the same across all branches of a parallel circuit. Since the voltage across each branch is known and the amount of current flowing through each is known, the resistance of each branch can be determined using Ohm’s law.To use the ohmmeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Use the reciprocal formula with the computed resistance values to calculate the total resistance of the circuit.

RT = 1/ R1 + 1/ R2 + 1/ R3 . . . 1/ Rn

RT = _______________ Ω

Use the ohmmeter to determine the total resistance of the circuit

RT = _______________ Ω

Notice that the total circuit resistance is less than any single resistor in the circuit. To understand this, recall that resistance is hindrance to the flow of current. Each time another branch is connected to the power source, another path for current flow is created. This reduces the hindrance to current flow for the circuit. The total resistance of a parallel circuit will always be less than the resistance of any single branch. There are three formulas used to calculate the total resistance of a parallel circuit when only resistance values are known. The first formula is called the “product over sum” formula.

Press the play button on the bottom left of the screen to activate the power source. Notice that information about the circuit will be displaced at important locations (such as the resistors). Every Circuit does not have a multimeter as a whole but it has it in parts. You can find along the parts menu a voltmeter, ampere meter and an ohmmeter. To use the multimeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Using an Ammeter, measure the amount of current across each of the resistor.

R1 = _________ A

R2 = _________ A

R3= _________ A

Add the current across each resistor. Compare the sum with the current of the circuit.

(I1 + I2 + I3 ) _______________ amps

Calculate the total circuit current using the total circuit voltage and total resistance. Compare this calculated value with the measured value.

IT = _______________ amp(s)

Turn on the 120 volt power supply and measure the current flow in the circuit.

I = _______________ amp(s)

Laboratory 4: Combination Circuit

Combination circuits contain both series and parallel paths in the same circuit. In order to solve unknown values, it is imperative to be able to identify which components are in series and which are in parallel. To determine which components are in series and which are in parallel, trace the current path through the circuit.

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

The simplest way to go about this is to acquire all the resistors we need and then place them. Click on the resistor icon 5 times so that you have 5 resistors sitting in the top left corner of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen

Now just arrange the resistors as they are in figure, To connect the "wires", simply click on the nodes of the resistors you would like to join.

Resistor R1 has a value of 250Ω, R2 has a value of 500Ω, R3 has a value of 300Ω, R4 has a value of 300Ω and R5 has a value of 600 Ω. The battery has a terminal voltage of 120 volts. To use the ohmmeter, simply attach it to the nodes you wish to measure over as you would with the multimeter. The following electrical values will be determined for this circuit:

RT - Total resistance of the circuit

IT - Total circuit current

I1 - Current flow through resistor R1

I2 - Current flow through resistor R2

E1 - Voltage drop across resistor R1

E2 - Voltage drop across resistor R2

I3 - Current flow through resistor R3

E3 - Voltage drop across resistor R3

E4 - Voltage drop across resistor R4

E5 - Voltage drop across resistor R5

I4 - Current flow through resistor R4

I5 - Current flow through resistor R5

When solving values for a combination circuit, it is generally helpful to reduce the circuit to a simple series or parallel circuit and then work back through the circuit in a step-by-step procedure. This is accomplished by combining series or parallel components to form a single resistance value. In the circuit, resistors R2 and R3 are connected in parallel. These two resistors can be combined into one resistor value by determining their total resistance value.

Use the reciprocal formula with the computed resistance values to calculate the total resistance of the parallel circuit.

RT = 1/ R1 + 1/ R2 + 1/ R3 . . . 1/ Rn

RT = _______________ Ω

Calculate the total circuit resistance of the circuit

RT = _______________ Ω

Use the ohmmeter to determine the total resistance of the circuit

RT = _______________ Ω

The total resistance for resistors R2 and R3 will form resistor Rcombination. Notice that resistors R2 and R3 have been replaced by Rcombination. The circuit is now a simple series circuit containing two resistors, R1 and Rcombination. One of the rules for series circuits states that the total resistance is equal to the sum of the individual resistances. The total circuit resistance can be determined by adding the two resistance values together.

Resistor Rcombination is in reality resistors R2 and R3. The values that apply to Rcombination, therefore, apply to resistors R2 and R3. If a voltmeter were to be connected across the parallel circuit containing R2 and R3, it would indicate the same voltage drop as that across Rcombination, One of the rules of parallel circuits is that the voltage must be the same across all branches of the circuit.

Press the play button on the bottom left of the screen to activate the power source. Notice that information about the circuit will be displaced at important locations (such as the resistors). Every Circuit does not have a multimeter as a whole but it has it in parts. You can find along the parts menu a voltmeter, ampere meter and an ohmmeter. To use the multimeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Using an Ammeter, measure the amount of current across each of the resistor.

R1 = _________ A

R2 = _________ A

R3= _________ A

R4 = _________ A

R5= _________ A

Using an voltmeter, measure the amount of voltage drop across each of the resistor.

R1 = _________ V

R2 = _________ V

R3= _________ V

R4= _________ V

R5= _________ V

Calculate the total circuit current using the total circuit voltage and total resistance. Compare this calculated value with the measured value.

IT = _______________ amp(s)

Laboratory 4: Input and Output Impedance

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

The simplest way to go about this is to acquire all the resistors we need and then place them. Click on the resistor icon 4 times so that you have 4 resistors sitting in the top left corner of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen

Now just arrange the resistors as they are in figure, To connect the "wires", simply click on the nodes of the resistors you would like to join.

Now, we just need to set the values for each resistor (note they are all currently 1K). To do this, click on the resistor and click on the wrench shaped button on the bottom left of the screen. Every Circuit does not have a multimeter as a whole but it has it in parts. You can find along the parts menu a voltmeter, ampere meter and an ohmmeter. To use the ohmmeter, simply attach it to the nodes you wish to measure over as you would with the multimeter.

Take note that the ohmmeter acts as a 1V source. Think about it, multimeters use ohms law for their calculations (V = IR). With V = 1, we can get the direct value of R knowing the current we get through our source! It's the simple things in life that help the most.

Laboratory 6: PN Junction Diode

A diode is an electrical device allowing current to move through it in one direction with far greater ease than in the other. The most common kind of diode in modern circuit design is the semiconductor diode, although other diode technologies exist. Semiconductor diodes are symbolized in schematic diagrams such as the figure below. The term “diode” is customarily reserved for small signal devices, I ≤ 1 A. The term rectifier is used for power devices, I > 1 A.

When placed in a simple battery-lamp circuit, the diode will either allow or prevent current through the lamp, depending on the polarity of the applied voltage.

When the polarity of the battery is such that current is allowed to flow through the diode, the diode is said to be forward-biased. Conversely, when the battery is “backward” and the diode blocks current, the diode is said to be reverse-biased. A diode may be thought of as like a switch: “closed” when forward-biased and “open” when reverse-biased.

The direction of the diode symbol’s “arrowhead” points at the direction of the current in conventional flow. This convention holds true for all semiconductors possessing “arrowheads” in their schematics. The opposite is true when electron flow is used, where the current direction is against the “arrowhead”.

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

Click on the resistor icon 1 time , Diode icon 1 time and LED icon 1 time, sitting on top of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen. To connect the "wires", simply click on the nodes of the resistors you would like to join. Now, we just need to set the values for each resistor. To do this, click on the resistor and click on the wrench shaped button on the bottom left of the screen.

Set the source to 9 V and Press the play button on the bottom left of the screen to activate the power source, you should see your diode light up on the circuit. Then you can set the forward bias voltage to what you think its going to be or (if your doing the lab right this instant) set the forward bias voltage (simply the voltage setting for LED's) to what you found it to be.

Press the pause button on the bottom left of the screen to diactivate the power source, Then you can set the source into reverse the polarity to what you think its going to be.

Laboratory 7: LED light source

This circuit is a great starter project for beginners. To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down LED and Resistor.

Click on the resistor icon 1 time and LED icon 1 time, sitting on top left corner of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen. To connect the "wires", simply click on the nodes of the resistors you would like to join. Now, we just need to set the values for each resistor (note they are all currently 1K). To do this, click on the resistor and click on the wrench shaped button on the bottom left of the screen.

Set the source to 9 V and Press the play button on the bottom left of the screen to activate the power source, you should see your diode light up on the circuit. Then you can set the forward bias voltage to what you think its going to be or (if your doing the lab right this instant) set the forward bias voltage (simply the voltage setting for LED's) to what you found it to be.

Laboratory 8: Transistor as a Switch - NPN

One of the most common uses for transistors in an electronic circuit is as simple switches. In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on.

In an ideal switch, the transistor should be in only one of two states: off or on. The transistor is off when there’s no bias voltage or when the bias voltage is less than 0.7 V. The switch is on when the base is saturated so that collector current can flow without restriction.

Look at this circuit component by component:

LED: This is a standard 5 mm red LED. This type of LED has a voltage drop of 1.8 V and is rated at a maximum current of 20 mA.

R1: This 330 Ω resistor limits the current through the LED to prevent the LED from burning out. You can use Ohm’s law to calculate the amount of current that the resistor will allow to flow. Because the supply voltage is +6 V, and the LED drops 1.8 V, the voltage across R1 will be 4.2 V (6 – 1.8). Dividing the voltage by the resistance gives you the current in amperes, approximately 0.0127 A. Multiply by 1,000 to get the current in mA: 12.7 mA, well below the 20 mA limit.

Q1: This is a common NPN transistor. A 2N2222A transistor was used here, but just about any NPN transistor will work. R1 and the LED are connected to the collector, and the emitter is connected to ground. When the transistor is turned on, current flows through the collector and emitter, thus lighting the LED. When the transistor is turned off, the transistor acts as an insulator, and the LED doesn’t light.

R2: This 1 kΩ resistor limits the current flowing into the base of the transistor. You can use Ohm’s law to calculate the current at the base. Because the base-emitter junction drops about 0.7 V (the same as a diode), the voltage across R2 is 5.3 V. Dividing 5.3 by 1,000 gives the current at 0.0053 A, or 5.3 mA. Thus, the 12.7 mA collector current (ICE) is controlled by a 5.3 mA base current (IBE).

SW1: This switch controls whether current is allowed to flow to the base. Closing this switch turns on the transistor, which causes current to flow through the LED. Thus, closing this switch turns on the LED even though the switch isn’t placed directly within the LED circuit.

You might be wondering why you’d need or want to bother with a transistor in this circuit. After all, couldn’t you just put the switch in the LED circuit and do away with the transistor and the second resistor? Of course you could, but that would defeat the principle that this circuit illustrates: that a transistor allows you to use a small current to control a much larger one.

If the entire purpose of the circuit is to turn an LED on or off, by all means omit the transistor and the extra resistor. But in more advanced circuits, you’ll find plenty of cases when the output from one stage of a circuit is very small and you need that tiny amount of current to switch on a much larger current. In that case, this transistor circuit is just what you need.

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

Click on the resistor icon 2 time , NPN Transistor icon 1 time and LED icon 1 time, sitting on top of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen. To connect the "wires", simply click on the nodes of the resistors you would like to join. Now, we just need to set the values for each resistor. To do this, click on the resistor and click on the wrench shaped button on the bottom left of the screen.

Set the source to 6 V and Press the play button on the bottom left of the screen to activate the power source, you should see your diode light up on the circuit. Then you can set the forward bias voltage to what you think its going to be or (if your doing the lab right this instant) set the forward bias voltage (simply the voltage setting for LED's) to what you found it to be.

Press the pause button on the bottom left of the screen to diactivate the power source, Then you can set the resistor connected next to the base of the transistor to ground to what you think its going to be or (if your doing the lab right this instant) set the reverse bias voltage to what you found it to be.

Laboratory 9: Transistor as a Switch - PNP

To do this we will simply drag and drop the components in every circuit. Do not yet add power so all we will be placing down are resistors.

Click on the resistor icon 2 time , PNP Transistor icon 1 time and LED icon 1 time, sitting on top of your screen. We don't need to click the ground component because a ground is already provided by default in the middle of the screen. To connect the "wires", simply click on the nodes of the resistors you would like to join. Now, we just need to set the values for each resistor. To do this, click on the resistor and click on the wrench shaped button on the bottom left of the screen.

Set the source to 6 V and Press the play button on the bottom left of the screen to activate the power source, you should see your diode light up on the circuit. Then you can set the forward bias voltage to what you think its going to be or (if your doing the lab right this instant) set the forward bias voltage (simply the voltage setting for LED's) to what you found it to be.

Press the pause button on the bottom left of the screen to diactivate the power source, Then you can set the resistor connected next to the base of the transistor to ground to what you think its going to be or (if your doing the lab right this instant) set the reverse bias voltage to what you found it to be.