 Good morning everyone, I am Professor Rushan Mistry and for today's session we will be discussing potentiometers. Now the learning outcome of this session is you will be able to list types of potentiometers and enumerate applications of these particular potentiometers. We will see applications both as sensors and as a control for an external source. Now potentiometers we have studied since 11th, 12th and also during measurement systems class. So this is a quick review of the same. So a potentiometer I have abbreviated it as a pot. A pot is an electromechanical device containing an electrically conducive wiper that slides against a fixed resistive element according to the position or angle of an external shaft. The electrically the resistive element is divided at the point of the wiper. This is here itself as you can see. To measure displacement a pot is typically wired in a what is called as voltage divider configuration. So as this moves the output voltage changes and then this can be used to estimate the displacement which is causing this particular wiper to move. Now always we expect the measurement in the linear range and most potentiometers have a very high linear range. So here displacement and output are actually measured and the output obviously being the voltage and here input being the displacement. The circuit's output is a function of the wiper's position and is an analog voltage available for direct use and for digitization. So in a if this is provided to a computer or a controller then this will be converted into a digital form and then it will be converted. Electrically the resistive element is divided at the point of the wiper contact and to measure a pot is typically wired in what is called as voltage configuration. I am reiterating this. This is typically the arrangement of the same. Now since we have already studied in the past we are actually more interested in finding out the typical applications of these particular devices for our current course. So before we proceed to that just try to observe how these things look like. I always recommend that you do an image search of potentiometers. So you can type in basically potentiometers do an image search, collect those images compile the images and see how they look like. So you can visually identify them once you see them in the laboratory set up or on circuit boards or in any place when you encounter these. So typically we have linear pots, rotary pots and there are some which are called as helicolor hybrid pots. Now all these have been put over here and we will be discussing the same. This is an internal structure of a potentiometer rotary potentiometer of course which is available in any electronic shop. You can cheaper ones are available you can have a look at this open it up and see for yourself. I definitely recommend this you can have a go at it once. And this you can find also in electronic stores these are usually the cheaper and these also called as streamers. They are not used for sophisticated sensing purpose but they are often used to regulate voltages and currents on basically breadboards and circuit boards. Again there are certain nomenclature which are associated with potentiometers. This is often not discussed in book but this is very common you can say nomenclature in the electronics industry. So this is what is called as a dual gang potentiometer. This is a concentric potentiometer, a multi-turn potentiometer, a multi-turn linear which is called as shrimp pot, a slide type potentiometer and obviously what is called as a motorized fader. Extensive used in audio and video signal conditioning we will find this and obviously other sensing applications are as well. This is again an example of how you can use a potentiometer for audio control. I recommend this particular exercise. What you can do is you have one right signal source, a left signal source which you can connect to a potentiometer and then this output you can go to an amplifier setup. So you can use this actually to have some sort of a volume control. Now as an example what you can do is if you can find an old computer speaker. Especially if the volume control is actually not working then it is even well and good. Get hold of a speaker, dismantle it, check the connections, make the connections as you can see it over here and see if it works. So this is a sort of a small assignment which you can do for your own sake. We typically try this and this is a fun part actually to start working on how potentiometers can be used. That is why I said one more thing is see if you can find applications where we can use potentiometers in our laboratory projects. We do laboratory projects which include automobile projects, other projects in control engine. Just think of some examples where you can see an application where a potentiometer can be used. Let us say for example robot sensing. So that is one of the examples I can use. So think of at least five examples and then we can talk more on the same. Now let us continue with our application of potentiometers from every lift man. We saw a simple exercise which you can do where you can use a potentiometer for volume control. And you can actually use potentiometers to control the intensity of light as well. Though most of these, the lights which are available do not have this. It is available in the market and you can use it in your house just to tinker and see how you can control the intensity of a light. But now let us get some overview of the applications. We saw different types of pots, singleton, multiple turns, gang pots in the past, the image which you had seen in the previous slide. Now there are general application domains for each. For example singleton pots, obviously these are the most common used in audio, video, signal, level control and speed control. So very common if you have a tape recorder, whenever you move the volume knob and any other knob, remember it is a potentiometer which is underneath there. Then you have multi-turn pots. These are used for precision and higher resolution application. If typically more than one turn the knob keeps on moving, it is typically a multi-turn pot. In the internal combustion engine's lab, this particular multi-turn pot is used in order to set the load on the dynamometer more accurately. So that is where one application within the laboratory is what we have. Then we have what is called as a dual-gang pot where you two channels have to adjust where we have to adjust two channels simultaneously. In that case, this particular dual-gang pot is used. Then you have concentric pots where two controls have to be combined in one. Then you have servo pots which is specifically used in precise position and motion control applications. And then you have oil field potentiometers which find application in R and D industrial and marine applications. So this is again a very, you can say in a nutshell the review you can find for different potentiometers. So let me iterate, singleton pots which are the most common multi-turn pots which find application in high precision resolution. Gang pots, dual-gang pots where two channels have to be adjusted simultaneously. Concentric pots where two controls are to be combined in one. Servo pots of precise motion control. And then oil field potentiometers for very specialized applications in R and D industry and other maritime applications. Now, again, going ahead with the applications, we can generalize rotary position sensors are typically used in applications where a user needs to control a variable output, let's say such as a frequency, speed or volume control. And typical applications include test and measurement equipment. If you have all test and measurement equipment, you will find a potentiometer. Consumer electronics, small engines, robotics and medical equipment. So any type where you require control and you just remember if you're moving a knob somewhere and it is in ensuring some sort of a control is very likely that's a potentiometer which is being used. And then, again, we can such an application domains can be grouped like this. You'll find them in motor handling vehicles, wheelchairs, off-road vehicles, construction equipment, HMI applications, road rollers, optical characterization machines. Now, how do you actually come up with these, you can say application domains? Best way is to look up a manufacturer's website. So just make a list of five manufacturers of potentiometers. Look up their websites and see what domains these guys are supplying their particular products to. So it will give you an idea of where potentiometer is used. Obviously, you have to elaborate where in these particular devices they find application. When the application then can be correlated as a remember for speed control or some sort of a position control. But this you can say characterize a general domain of applications of potentiometers. Just an overview, there are plenty more applications like this. Now, going further, more applications for multi-turn spots specifically. Now, those applications which were developed or discussed in past were general domains. Now, multi-turn spots specifically are used for actuator controls in level measurement and process automation systems in signal and telecommunication equipment and obviously sophisticated test and measurement equipment. So these are multi-turn pots are given you, you guys from two different sources. Like I said, you have to learn to visually identify this and find out what the typical domain of application they belong to. Then more applications, power supplies, draw wire sensors to determine position on industrial controls of operating machines and robots which control motion. So they have a very wide range of application multi-turn pots. And if you take a look at it, they are the most widely built pots also by the manufacturers. Then you have linear potentiometers. So anywhere where you need to measure a linear displacement, there injection, like such for examples in injection molding machines, textile machines, special purple machines, medical diagnostics, okay, control equipment for hydroelectric power plants. In obviously in education kits and supplies as well you can use for linear potentiometers. Hollow pots, again a very wide application is for hollow potentiometers. They are applications in typically robotics for actuator control, gear, position feedback controls in gaming consoles. Whenever you move your joystick, typically it's connected to a hollow pot and as you move the voltage changes and that feedback is given in which obviously corresponds to a point on the screen. Then as a seat position sensor and also in commercial mover machines. So this is a very wide application area for hollow pots. Then angle sensing spot. I mean this is a specific case. Best example actually is a joystick. So these find application in weather instruments. Anywhere you have a joystick control like in cranes, okay, other forklifts, any other equipment where the control is in the fire and joystick. Power generation equipment, some textile machines, a simulation, cement machinery and automation. Wherever joystick control comes into pressure, you will have angle sensing pots. Now I definitely recommend that you read mechatronics handbook by Bishop. There is extensive information regarding all sensors including potentiometers for the same. Then you can read my introduction to mechatronics by Poulton where you find the basic construction working on potentiometers. But when it comes to applications, I urge everybody to actually go to the websites of manufacturers, make a list of manufacturers, go to their websites and then find out their application domains. So for the next class, we will look at other types of sensors and their applications. Thank you.