Transistor as a switch experiment pdf

In this experiment we will examine some of the characteristics of transistors in these modes of operation. A transistor is an electronics component that is also used as a digital switch. The diode test function of a multimeter is more reliable than using an ohmmeter. Bipolar junction transistors bjt general configuration and definitions the transistor is the main building block element of electronics.

Measure the characteristics of an emitter follower circuit. In a transistor a very small current input signal flowing emitter tobase is able to control a much larger current which flows from the system power supply, through the transistor emitter tocollector, through the. Bjt characteristics theory the transistor is a two junction, three terminal semiconductor device which has three regions namely the emitter region, the base region, and the collector region. The one youre using for this lab is an npntype transistor called a tip120.

Bipolar junction transistors also known as bjts can be used as an amplifier, filter, rectifier, oscillator, or even a switch, which we cover an example in the first section. In most digital ics transistors will work as a switch to make power consumption very low. When no base voltage is present, the switch is off. The tip transistor has a heatsink, telling you that its designed to operate in the active region analog circuits. Dont try and switch ac voltage using the methods youre about to see, these are strictly dc circuits.

Nov 26, 2012 switch is a very useful and important application of transistors. Both npn and pnp transistors can be used as switches. Diefenderfer and holton, principles of electronic instrumentation. Im currently on a section where im building circuits where im using a transistor as a switch. Note that because it is a particular type of transistor, the primary applications of bjt center on either amplifying electronic signals or switching. Transistor as a switch discrete semiconductor circuits. A darlington pair behaves like a single transistor with a very high current gain. These switches are also very useful to the output of an optranslateamp comparator to the proper 1 and 0 voltage levels of a digital logic circuit input. During the experiment, we tried to increase the temperature by connecting. When a transistor is on, its collector and emitter act as a short circuit. Transistor works in saturation and cutoff regions when it works. Some of these have the ability to test other parameters of the transistor, such as leakage and gain.

We will discuss the need for proper biasing in the next chapter. Active, cutoff and saturation according to applied biasing condition. The bipolar junction transistor bjt as a switch bipolar. The transistor has three electrodes, and a base used to control the transistor, the collector and emitter. Single transistor switches are useful as a way to adapt a relatively lowpower opamp output in order to switch a highcurrent or high voltage device on and off.

After reading the following elementary introduction to the bjt, be sure to read sedra and smith, microelectronic circuits 4th edition, ss4 pp. Pdclabmanual transistor as a switch electrical engineering. Finally, describe how the activities in this experiment helped you to understand more. Virtually any general purpose npn or pnp transistor can be used as a switch. A metaloxidesemiconductor fieldeffect transistor mosfet is a threeterminal device that can be used as a switch e. It is a semiconductor device and it comes in two general types. The bipolar junction transistor bjt as a switch all about circuits. Bjt digital switch objectives the purpose of this lab is to acquaint you with the basic operation of bipolar junction transistor bjt and to demonstrate its functionality in digital switching circuits. Driving it in either cutoff or saturation mode, the transistor can create the binary onoff effect of a switch. Two of the most important applications for the transistor are 1 as an amplifier in analog electronic systems, and 2 as a switch in digital systems. Before starting the first experiment, lets learn about some of the basic electronic components.

Working of transistor as a switch npn and pnp transistors. Hence v 0 is approximately equal to v cc, when ip voltage v i is changed to positive. Pnp transistors can also be used as switching devices and an example of a pnp transistor switch is shown below. Electricity is a flow of subatomic very, very, very, small particles, called electrons. This tutorial is about transistor as a switch with block diagram and circuit diagram. Then describe how a transistor can be used as a switch and why it is useful in that role. Here, let us focus how a transistor works as an amplifier. Since an integrated circuit is constructed primarily from dozens to even millions of transistors formed from a single, thin silicon crystal, it might be interesting and instructive to.

How to use a transistor as a switch in different applications. We can increase the sensitivity of this touch sensor device by connecting two or more transistors so. Measure and record in to demonstrate this switching ability. In this transistor tutorial, we will learn about the working of a transistor as a switch.

On this channel you can get education and knowledge for general issues and topics. Trainer kit, patch cords, dc power supply, function generator. Mar 28, 2017 this makes this darlington transistor array suitable for driving the relay or motor up to 500ma this is a maximum datasheet value directly from the microcontroller output. Take note that both operational purposes of a transistor, specifically as an amplifier and as a switch, were originally reserved only for electron vacuum tubes. When using the bipolar transistor as a switch they must be either fullyoff or fullyon. Experiment 6 transistors as amplifiers and switches. Transistor as switch amplifier transistor as a device switch and amplifier we have read about the configurations in which the transistor can be connected. Using the diode or resistance test function on a multimeter, you can measure across the be and bc terminals to check for the presence of those diodes. The transistor is the reason why your cell phone fits inside your pocket and why your spikerbox can measure spikes from neurons.

Physics project report on transistor, action of transistor. The transistor will operate as an amplifier or other linear circuit if the transistor is biased into the linear region. If the transistor has a heat sink, its designed to operated in the active state where i 0 and vce 0. But a digital high logic signal controls this switch as compared to traditional push buttons. Transistors that are fully on are said to be in their saturation region. The input signal is applied between the base and emitter, and the output is taken from the collector and emitter.

In this experiment we will discuss ways in which transistors can be used as amplifiers and to create binary signals by acting as a switch between two output voltage states. Although, it works similarly to a mere mechanical switch. Mar 21, 2018 hello, im new to electronics and im reading a book currently to learn more about the topic. Transistor work as a switch when it is in cutoff and saturation regions.

Ndsu transistors used as a swi tch ece 321 jsg 1 february 10, 2020. To study and verify the functionality of a pn junction diode in forward bias b pointcontact diode in reverse bias components equipments required. When using the bipolar transistor as a switch they must be either fully off or fullyon. Transistor switches are critical circuitbuilding blocks.

In addition to the traditional dmms there are also transistor testers. In this part of the experiment we wish to construct a sensor that will turn the led on simply by touching a wire. A transistor is used for switching operation for opening or closing of a circuit. After reading this tutorial you ll get to know how transistor acts as a switch if it is npn or pnp. The transistor is used as a signal amplifier or as a switch. Transistor as a switch circuit diagram from the above circuit we can see that the control input vin is given to base through a current limiting resistor rb and rc is the collector resistor which limits the current through the transistor. This model is useful if you need to test a transistor.

For example, if youre building an hbridge circuit to control the motors on a battery operated robot, you wouldnt use four transistor switches because of the large. This ability to turn the power mosfet on and off allows the device to be used as a very efficient switch with switching speeds much faster than standard bipolar junction transistors. This type solid state switching offers significant reliability and lower cost as compared with conventional relays. May 14, 2019 in this transistor tutorial, we will learn about the working of a transistor as a switch. Unfortunately, in some cases, its not the best solution. Bipolar junction transistor as a switch iosr journal. The transistor allows you to control a circuit thats carrying higher current and voltage from the microcontroller. The purpose of this laboratory is to become familiar with the d. Pdclabmanual transistor as a switch free download as pdf file. One of the most common uses for transistors in an electronic circuit is as simple switches. But recently one of my friend from ethiopia said that he wanted to do something that does not includes a microcontroller or arduino but still its worth making in a weekend and also. The transistor switch can be very useful in a variety of circuits. Astable multivibrator using transistors electrosome.

So in the above circuit when a transistor is in off state its collector will have the voltage vcc and when it is on its collector will be grounded. Transistor switch connected to relay and control the external load activity number of the gce advanced level practical guide 24. Using a transistor to control high current loads with. A transistor switch, which is used for opening or closing of a circuit, that means the transistor is commonly used as a switch in the electronic devices only for the low voltage applications because of its low power consumption. This tutorial shows how to wire a transistor as a switch. We control traditional switches manually by applying a mechanical force. In short, a transistor conducts current across the collectoremitter path only when a voltage is applied to the base. Introduction so far in ee100 you have seen analog circuits. Objective to measure and understand the currentvsvoltage.

Transistor switch connected to relay and control the. Transistor is a three terminal, bipolar, current controlled device. Transistors are built by stacking three different layers of semiconductor material together. The properties of transistors will be studied in this module so basically the focus here is understanding how transis. Transistor switch connected to relay and control the external load 69 workshop on biosystems technology held at university of kelaniya from 20 to 27 june 2015 lesson 11 title of the experiment. A transistor acts as an amplifier by raising the strength of a weak signal. Also, to design a suitable driver circuit for a given load using transistor. Transistor characteristics lab introduction transistors are the active component in various devices like amplifiers and oscillators.

Simulation of transistor switch circuit physics forums. You will be using a 2n2222 transistor so your data will be different. When the ip voltage v i is negative or zero, transistor is cutoff and no current. See figure 15 and figure 16 for the pinout drawing and schematic symbol of the transistor. Since an integrated circuit is constructed primarily from dozens to even millions of transistors formed from a single, thin silicon crystal, it. Resistor values are not critical for this experiment. Switching and amplification are the two areas of applications of transistors and transistor as a switch is the basis for many digital circuits. I decided to experiment with the circuit they gave me and put it in a simulation software called proteus. When using the mosfet as a switch we can drive the mosfet to turn on faster or slower, or pass high or low currents. Diodes and transistors university of california, berkeley. In the above diagram we can find two transistors which is wired as a switch. Read about transistor as a switch discrete semiconductor circuits in our free electronics textbook.

Following our study of amplifiers, we turn to the use of the bjt as a switch, a fundamental element of a digital logic circuit. Thus transistor is working as a switch which can be made on or off by an external input. Design and create a spice model of a transistor operating as switch. Ndsu transistors used as a switch ece 321 jsg 1 february 10, 2020. It is also a very useful circuit for an electronics hobbyist as it can be used as a driver, inverter etc circuit diagram transistor as a switch. In this experiment, a transistor will be connected table 27 1 the voltage from point b to ground. Then you learned how circuit elements do not operate the same at all frequencies. For a transistor to act as an amplifier, it should be properly biased. A typical switching circuit using a pnp transistor is shown at the left. A practical switch experiences power loses during on state, off state and also during the transition state on to off or off to on.

For this purpose we will investigate one of the common transistors, the bipolar junction. Its a simple hookup and sketch and it illustrates how simple it is to control a load with a transistor and an arduino. You started with simple resistive circuits, then dynamical systems circuits with capacitors and inductors and then opamps. If you understood the working of the mosfet and its regions of operation, you would have probably guessed how a mosfet works as a switch. An npn transistor has an n type emitter, a p type base and an n type collector while a pnp transistor. How to use transistor as a switch with example circuits. By putting your meter across the resistoror light or motor as shown you will see the voltage going to the load. The american radio relay league, the arrl handbook. Transistor as switch objective the purpose of the experiment is to design and analyze the operation of transistor as switch. Controlling large voltage with smaller voltage or using.

The three terminals are referred to as the source, gate, and drain terminals. The actual transistor used as a switch is not critical in these applications. The base is compared to other much thinner electrodes up to 100 times. May 26, 2015 this tutorial is about transistor as a switch with block diagram and circuit diagram. The data below were collected for the example of a npn 2n36443 transistor using the circuit below. Neither is the particular light emitting diode led selected. To operate the transistor as a switch, for on state it has to be operated in saturation region for on state and to be operated in cut off region for off state when the ip voltage v i is negative or zero, transistor is cutoff and no current flows through rc. Experiment 6 transistors as amplifiers and switches our final topic of the term is an introduction to the transistor as a discrete circuit element. As a student of class xii, i did this project as a part of my studies entitled. Transistor switches can be used to switch and control lamps, relays or even motors. As you can see, the transistor is acting as a kind of electricallycontrolled switch, switching current on and off to. This makes this darlington transistor array suitable for driving the relay or motor up to 500ma this is a maximum datasheet value directly from the microcontroller output.

To operate the transistor as a switch, for on state it has to be operated in saturation region for on state and to be operated in cut off region for off state. This is useful when you want to power a large load using a small physical switch. Transistor is a three terminal semiconductor device that amplify the current and used as a open close switch. Make sure to note whether it is an npn or pnp and polarize the test leads accordingly. The transistor characteristics are useful in amplifier design as well as understanding how transistors operate. Provide and briefly discuss at least one example of how a transistor switch can be used in a practical application or in the construction of an electronic device. Transistor as a switch is a very important and useful application of transistors.

Nov 27, 2012 please do read the article transistor as a switch. Physics investigatory class 12 linkedin slideshare. Basically i love to do projects that are microcontroller related. Jan 15, 20 how to use your transistor as a switch simplest way. Bipolar junction transistors also known as bjts can be used as an amplifier, filter, rectifier. This is the edited version of the investigatory project on physics with different topicto construct a switch using transistor and plot a graph bw input output slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The emitter is compared to the collector, which has the same conductivity type doped more. Then to summarise when using a transistor as a switch the following conditions apply. Construct and analyze a voltage regulator circuit for a solar panel. Analysis of mosfet as a switch with circuit diagram. Apply 1 hz square wave signal to the base and ground from function generator. They are called active devices since transistors are capable of amplifying or making larger signals. For this, experiment we will use the transistors in the commonemitter configuration.