Set the signal from the generator to 0 v to 10 v, 50% duty cycle square wave at 5 khz. On the picture shown above you could see how we connect the transistor as the high active switch logical high also known as low side switch using npn transistor and the low active switch logical low also known as high side switch using pnp transistor ok lets calculate each of the rb and rc value on this following npn transistor circuit. A relatively small flow of electrons sent through the base of the transistor has the ability to exert control over a much larger flow of electrons through the collector. Well in this example with just one low powered bulb that is probably true however, if there were for example 100 spotlight bulbs to switch on and off with one switch the total current to be switched would be five amps.
Since an integrated circuit is constructed primarily from dozens to even millions of transistors formed from a single, thin silicon crystal, it. To obtain common emitter characteristics of npn transistor introduction. A transistor is an electronics component that is also used as a digital switch. Active, cutoff and saturation according to applied biasing condition. When using the bipolar transistor as a switch they must be either fullyoff or fullyon. Simply open the pdfs that youd like to combine, select combine. Technical specifications characteristics supply voltage. Another kind of transistor is the junction field effect transistor of jfet. 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. When we choose a transistor as a switch, we have to care about the rating of the transistor. How to use transistor as a switch with example circuits. Pdf converter convert files to and from pdfs free online.
A switch consists of a bjt transistor that is alternately driven between the saturation and cutoff regions. 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. As a student of class xii, i did this project as a part of my studies entitled. Word, excel, ppt and image files will convert to pdf format. Transistors, however, have two pn junctions instead of just one like a diode has. Blog entry using transistor as a switch december 23, 2008 by rwb, under electronics most of microcontrollers work within 5 volt environment and the io port can only handle current up to 20ma. The american radio relay league, the arrl handbook. In this experiment we will examine some of the characteristics of transistors in these modes of operation. Transistors are made from the same ntype and ptype materials as diodes and employ the same principles. Transistor is three terminal active device having terminals collector, base and emitter. It is also a very useful circuit for an electronics hobbyist as it can be used as a driver, inverter etc circuit diagram. Power diode acting as a switch now the question that arises is that how does a diode acts as a switch. Then to summarise when using a transistor as a switch the following conditions apply.
Switching and amplification are the two areas of applications of transistors and transistor as a switch is the basis for many digital circuits. This lab activity describes the bjt when operated as a switch. Experiment 6, photodiode and phototransistor current. In an npn transistor operating in the active region, the emitter base junction is forward biased electrons and holes recombine at the. Transistor as a switch or bipolar junction transistor or. Phototransistor and ired part number index phototransistor part no.
Experiment 6 transistors as amplifiers and switches our final topic of the term is an introduction to the transistor as a discrete circuit element. Transistor as a switch dhirubhai ambani institute of. Finally, describe how the activities in this experiment helped you to understand more completely or accurately something you learned earlier. When the light is removed these photodetectors enter an. 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. Switch your meter to the 50ma range and connect it in series as shown on the schematic and in the pictorial. What links here related changes upload file special pages permanent link. You can intelligently search through pdf documents as quickly as word files. Turn on the power and set r 1 so that the lamp is off. Measure and record in to demonstrate this switching ability. Q11 is a common collector and q12 is a common emitter.
Physics project report on transistor, action of transistor. To construct a switch using a transistor and to draw the graph between the input and output voltage and mark the cutoff, saturation and active region. Pnp, is exactly the same the only difference being in their. This pair of transistors will buffer the signal from q3s collector, and provide a high gain as the signal goes to the final stage. As discussed earlier that the transistor can be used as a switch. The two pn junctions allow a transistor to perform more functions than a diode, such as acting as a switch or an amplifier. Verify that the output is correct by displaying both the input and the collector waveforms. Ndsu transistors used as a switch ece 321 jsg 6 february 10, 2020. Pspice simulation of bjt iv characteristics r c v cc i b simulation. Trainer kit, patch cords, dc power supply, function generator. A touch switch is an electronic device that enables us to control a circuit by simply touching a sensor. Packet switching in a circuit switch, path of a sample is determined at time of connection establishment no need for a sample headerposition in frame is enough in a packet switch, packets carry a destination field need to look up destination port onthefly datagram lookup based on entire destination address cell lookup based on vci.
The transistor as a switch because a transistors collector current is proportionally limited by its base current, it can be used as a sort of currentcontrolled switch. Thus transistor is working as a switch which can be made on or off by an external input. For this purpose we will investigate one of the common transistors, the bipolar junction transistor bjt. This paper presents the design of a clap activated switch device that will serve well in different phonocontrolled applications, providing inexpensive key and at the same time flee from false. Following our study of amplifiers, we turn to the use of the bjt as a switch, a fundamental element of a digital logic circuit. Physics investigatory class 12 linkedin slideshare. Pdf converter is a online webbased document to pdf converter software. Common practical examples of transistor as a switch transistor to switch the led. Explained it from transistor characteristics please watch.
Switch automatically turns native jobs into printready pdf files and notifies you immediately when a file contains errors. The anode of the scr2 is then reversebiased, causing it to turn off and light emission of the xenon lamp ceases. Transistor switch lab exercise multisim bipolar junction power transistor build the circuit in figure 1. Smart kit 1005 is a very easy project to built and will make you the proud owner of a magic switch that will respond to the slightest touch of your hand on its sensitive plates. The transistor as a switch experiment objectives g learning about the transistor as a switch g setting the transistors witching point with a voltage divider g crossing the switching point in the voltage divider with a variable resistance ldr and ptc s basic information in this experiment, the transistor is used as a switch in a simple circuit. Transistor as a switch when used as an ac signal amplifier, the transistors base biasing voltage is applied in such a way that it always operates within its active region, that is the linear part of the output characteristics curves are used. I hope you enjoyed this little article about using a transistor as a switch. According to link graph theory, inbound links pdf documents receive are. The schematic below shows how a transistor is used to switch the light emitting diode led. Experiment 5 the transistor switch and the transistor. Simulate the circuit with a 2n3904 bjt and rc 400 do a parametric sweep of the dc voltage source vcc with vcc ranging from 0 to 30 v use 0. Transistor switches can be used to switch and control lamps, relays or even motors.
Application circuits for the phototransistor switch application bulletin 2 optek technology 1645 wallace drive, carrollton, tx 75006 phone. Transistor as a switch discrete semiconductor circuits. Do a secondary parametric sweep on the current source with values of. The animations in this article may help visualise the theory for beginners such as design and technology students. Transistor switches and amplifiers equipment required. Experiment 5 the transistor switch and the transistor amplifier objective the objective of this laboratory session is to i demonstrate the ability of a transistor to act as a switch and ii demonstrate the ability of a transistor to amplify small signals by constructing a simple amplifier circuit. Transistor as a switch transistor as a switch experiment. Application circuits for the phototransistor switch. The principle of operation of the two transistor types. Electronics using an npn transistor as a switch duration.
Apply 1 hz square wave signal to the base and ground from function generator. It is a one way device, which only allows the flow of electricity in one direction only. These transistors help to form the input differential stage of the amplifier. Npn transistors can be used to switch ground to a device. Switch is a very useful and important application of transistors. A transistor is a semiconductor device used to amplify or switch electronic signals and electrical. 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. Because during on condition, the entire load current will flow through the transistor, if this current is more than a safe value of collectoremitter current carrying capacity of the transistor, then the transistor may be permanently destroyed due to overheating. The transistor data sheet shows variations in h fe from 100500. Experiment 1 the transistor as a switch what exactly is a multivibrator. When the switch is in the onstate, the scr2 and scr3 turn on to discharge capacitor c4 so that the xenon lamp is energized to emit light.
It is designed for general purpose switching applications and is housed in the sot. Diefenderfer and holton, principles of electronic instrumentation. When the switch at the base terminal is open, no current flows through the base so the transistor is in the cutoff state. We have discussec here the function and use of transistor as a switch. Transistor is widely used in amplifier, oscillator, electronic switch and so many other electronics circuits for variety of applications. The problem is that when the transistor is turned on, energy is store in the magnetic field of the inductor as e 1 2 li2. Mmbt4403m3t5g pnp switching transistor the mmbt4403m3t5g device is a spin. Switch software convert native files to printready pdf enfocus. For this purpose we will investigate one of the common transistors, the bipolar junction. Experiment 6 transistors as amplifiers and switches. The switch could simply have been placed in series with the led spotlight bulb rendering the transistor redundant. Although, it works similarly to a mere mechanical switch.
Transistors can also be used as switches but since this is not a course in digital electronics, we will not discuss the function of transistors. Transistor switch the objective of this part of the experiment is to design a transistor switch that will allow the relay to be operated from a 3 volt signal that is, relay off when the signal voltage is zero and relay on when the signal voltage is 3 volts. Transistors that are fully on are said to be in their saturation region. In most digital ics transistors will work as a switch to make power consumption very low. The basic bipolar transistor or bjt is two diodes constructed back to back on a piece of silicon.
We control traditional switches manually by applying a mechanical force. Working of transistor as a switch npn and pnp transistors. Assembling multiple documents into one is easy with a draganddrop interface in power pdf. In this video we cover briefly what a transistor is and discuss how to use them as an electrical switch dc only. Note when driving motors inductive loads if you have an inductive load, you need to add a flyback diode to the circuit. The switching configuration is for common emitter, the bias circuit is shown below. Hence v 0 is approximately equal to v cc, when ip voltage v i is changed to positive. Transistor is a three terminal, bipolar, current controlled device. Bipolar transistors are current regulating devices that control the amount of current flowing through them in proportion to the amount of biasing voltage applied to their base terminal acting like a currentcontrolled switch. Universal system and output transformer for valve amplifiers pdf. But a digital high logic signal controls this switch as compared to traditional push buttons.
Convert and create pdf from various types of files like word doc, excel xls. I hope i was able to make it easy to understand and factual in the same style as an encyclopaedia. When light is present, a phototransistor can be considered on, a condition during which they are capable of sinking a fair amount of current. In this experiment, a transistor will be connected table 27 1 the voltage from point b to ground. Bjt switch example suppose a bjt with a 5v supply is designed to switch a 5v, 20ma lamp on and off. You can experiment with other resistor values to find what the range of minimum and maximum. Drag and drop your file into the toolbox above to begin.
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