CircuitJS/C3/Silicon-Diode-Characteristics/English
| Visual Cue | Narration |
| slide:1 | Welcome to the spoken tutorial on Silicon Diode Characteristics using CircuitJS simulator. |
| Slide 2:
Learning Objective |
In this tutorial, we will learn about
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| Slide 3:
System Requirement |
To record this tutorial, I am using:
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| Slide 4:
Prerequisite |
To follow this tutorial, you should have a basic knowledge of
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| Slide 5:
What is a Diode? |
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| Slide 6:
Diode image Diode_Symbol.png |
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| Slide:
Diode Biasing |
The process of applying an external voltage to a p-n junction of a diode is called biasing.
There are two ways of Biasing:
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| Forward Bias
Forward_Bias_Diode.png |
In forward bias,
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| Show the circuit diagram | We will make this circuit to explain forward bias characteristics of the diode. |
| Show the diagram
Forward_Bias_Diode.png |
For Forward bias diode circuit, we require,
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| Keep the circuit diagram on top right | Let us open the CircuitJS interface.
In the menu bar, click on File and select New Blank Circuit. |
| Select variable voltage | Click on Draw, go to Inputs and Sources, and select Add Variable voltage.
Draw the variable voltage in the working area as shown. We require a voltage range of 0 to 2 volts. Right click on the variable voltage component and select the Edit option. In the Minimum voltage box, enter 0 and in the maximum voltage box, enter 2. Click on the OK button to save the changes. |
| Select Diode | Click on Draw, go to Active Components, and select Add Diode option.
Draw the diode in the working area. This is the default diode available on the CircuitJS platform. This diode has characteristics of a Silicon diode. Connect the P-junction of the diode to the variable voltage in the circuit. |
| Select Ammeter | Now, click on Draw, go to Outputs and Labels, and select Add Ammeter component.
Draw the ammeter in the working area as shown. Connect the ammeter to the N-junction of the diode. Next, we will connect a resistor to the ammeter. |
| Select Resistor | Go to Draw, select Add resistor option.
Drag and draw the resistor in the working area as shown. The default value of the resistor is 1 Kilo Ohm. Use the Edit option and change the resistor value to 1 Ohm. |
| Select Ground | Now, we need a ground component to complete the circuit.
Click on Draw, go to Inputs and Sources and select Add ground option. Draw and connect the ground component to the resistor in the circuit as shown. Observe the yellow dots indicating the current flow in the circuit. |
| On the right side, you will see a slider to change the voltage value.
Use the slider to change the variable voltage value to 0 volts as shown. | |
| We need a graph with relevant values of voltage and current.
These values will explain the V-I characteristics of a silicon diode. | |
| Select View in New Scope and open graph
Go to settings |
Right click on the diode and select View in New Scope option.
A graph will appear at the bottom of your screen. Increase the size of the graph by dragging the graph screen. At the bottom left corner, you will see a Settings icon, click on it. |
| Change the graph | A pop-window will open.
Click on the X-Y Plot option, check the Show V vs I checkbox. Click on the OK button to save the changes. The voltage values are plotted on the X-axis represented by the green line. The current values are plotted on the Y-axis represented by the yellow line. |
| FB_Observation Table.png | Create a table to note down the current readings for the given voltage values. |
| FB_0 volts.png
Silicon_Diode Video.mp4 (do not include from 6.38 to 8.06) |
At 0 volts, the ammeter shows no current flowing through the diode.
Hence, the current value for this condition is 0 Ampere. Notice the dot in the graph, it shows the voltage and current values. |
| Editing
Put a red box around the changes in values FB_0.5 volts.png |
Now, we will gradually increase the variable voltage using the voltage slider.
Note the changes in the voltage and current in the circuit. For voltage value 0.5 volts, the ammeter shows negligible current flow through the diode. We can see the dot on the graph moving along the x-axis. |
| FB_0.7 volts.png | As we increase the voltage value to 0.7 volts, the ammeter shows an increase in the current value.
The dot in the graph moves on the Y axis which shows increase in current. This point where the current increases is called the knee voltage. Thus, the knee voltage for the silicon diode is 0.7 volts. |
| Move the slider the slowly
FB_2 volts.png |
Note down the current reading for the remaining voltage values of 1 volt, 1.5 volts and 2 volts.
Notice the dot in the graph showing an increase in the current value. Hence for input voltage above 0.7 volts, the silicon diode acts as a conductor. |
| Let us now see how a diode behaves in reverse bias mode. | |
| Slide:
Reverse_Bias_Diode.png |
In reverse bias,
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| Reverse_Bias_Diode.png | We will create this circuit to explain reverse bias characteristics of the diode.
Go back to the CircuitJs simulator. |
| Let us first set the variable voltage value to 0 volts using the slider. | |
| CircuitJS Explanation | Click on the RUN/Stop button on the top right corner to stop the simulation.
Click on the Reset button to erase the forward bias V-I characteristics graph. |
| Let us change the circuit for Reverse bias mode.
Right click on the diode and select the Swap Terminals option. The positive end of the supply is now connected to the cathode of the diode. The negative end is connected to the anode of the diode. A reverse bias diode circuit is ready. | |
| click on the RUN/Stop button | Now, start the simulation by clicking on the RUN/Stop button again.
Since voltage is not applied to the circuit, current cannot pass through the circuit. |
| RB_Observation Table.png
Editing Red box around the negative value |
Let us increase the variable voltage from 0 to 2 volts using the slider.
Refer to the observation table for the diode connected in reverse bias mode. Since the diode is connected in reverse bias, the voltage and current readings will be negative.
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| Show dot in the graph | For all voltage values, the current flowing through the diode is negligible.
Notice the dot on the graph, which moves along the negative x-axis. This indicates that there is no change in the current flowing through the diode. |
| Slide:
Diode Characteristics |
Thus we can conclude the following;
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| This brings us to the end of the tutorial. Let us summarize. | |
| Slide Summary | In this tutorial, we learnt about
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| Slide:
Assignment |
As an assignment,
Hint - Double click on the diode and select 1N34 (germanium diode). |
| Slide :
About Spoken Tutorial project |
The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
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| Acknowledgement | Spoken Tutorial project was established by the Ministry of Education(MoE), Govt of India |
| Thank you | This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.
Thank you for watching. |
