Op-Amps - Using Operational Amplifiers

today in the workshop we're working with operational amplifiers you'll see how op amps work and how to use them in several popular configurations we'll also build a light activated switch a dual power supply and will use op amps with an Arduino we're back in operation today so welcome to the workshop [Music] [Applause] well hello and welcome to the workshop and today we're going to be working with operational amplifiers more commonly known as op amps now op amps have been available in integrated circuit format for about six decades now and during that time they have been used in thousands and thousands of different analog designs one of the reasons for their popularity is because they are so versatile you can literally configure an op amp in a couple of dozen different ways and each of those configurations can be considered to be an analog building block that you can use to build more complex circuitry op-amps can also be used to interface analog Electronics to Digital Electronics op amps are also extraordinarily inexpensive in fact one of the op amps we're using today is a quad op amp that costs all of 40 cents so each op amp costs a dime now what we are going to do today is we're going to of course start by learning a bit about op amps and then we're going to put some of that theory into practice we're going to take an op amp put it on a solid spreadboard and wire it in a number of different configurations after that I'm going to show you how we can use an op amp with a microcontroller we're going to connect one to an Arduino Uno after that we're going to build a little project the light sensitive switch that is built with an op amp and will probably cost you about two dollars in components to put together and finally many op amps need a dual power supply a supply with both a positive and a negative component While most of us have bench supplies that only are single power supplies so we're going to build a converter that converts a single Supply to a dual Supply and of course that converter is going to be built with an op amp I told you these things are versatile so let's start off by learning a bit more about operational amplifiers an op-amp is a high gain differential amplifier it has both a positive or non-inverting and negative or inverting input an op-amp amplifies the differences between these two input voltages these devices are characterized by having a very high input impedance and a very low output impedance originally operational amplifiers were developed for analog computers analog computers used voltages to represent numbers the first operational amplifier was built with vacuum tubes in 1941. the ua-702 was the first integrated circuit operational amplifier and it was designed in 1963. the schematic symbol for an operational amplifier is closed as a triangle with a number of connections to it on the top we have the positive power and on the bottom the negative power most operational amplifiers require a bipolar power supply with both positive and negative components there are two inputs in the op amp and inverting input and the non-inverting input note that the inverting input on top and the non-inverting on the bottom is not a convention and when you see op amps drawn in schematic diagrams you can see it drawn the other way around as well it just depends what looks better on the diagram finally the output of the op amp is at the point of the triangle in order to visualize how an operational amplifier works first we need to Power It Up we will use a bipolar power supply for the op-amp that has both a positive and a negative component note that the power supply has a common ground point this ground point is a reference point we'll also connect two input voltages to our operational amplifier V1 which is connected to the inverting input and V2 which is connected to the non-inverting input again the two voltage is reference the same Common Ground point if we apply a voltage of 4 volts to V1 and 6 volts to V2 that'll create a difference of positive 2 volts since this is a positive difference our output will be positive and the greater difference the greater the output will be if we increase V1 to dine volts then our difference will be negative 3 volts and so our output will go negative again the amplitude of the output will depend on the amount of difference between the two inputs if we reduce V1 to 6 volts and keep V2 at 6 volts there'll be no difference between the two inputs therefore the output of the operational amplifier will be zero by itself an operational amplifier has a great deal of gain in fact the typical op-amp has a gain of a hundred thousand times or more since this is likely too much for our circuit we need to regulate it and we can do that by applying feedback which is to take the output of the op amp and apply it to one of its inputs over here I show it being applied to the inverting input this will actually create an amplifier whose gain is only one in other words what goes into the amplifier will be what comes out since we might want a little bit more gain than that but not the infinite amount of gain that we get with the open loop we can apply a feedback resistor the value of the resistor will determine the gain of the amplifier and the higher the value of the resistor the higher the amplifier is gain will be a common configuration for an operational amplifier is as an inverting amplifier an amplifier whose output is 180 degrees out of phase with its input the two components used with the operational amplifier in this configuration are the input resistor and the feedback resistor and these two components determine the gain of the inverting amplifier another common configuration is the non-inverting amplifier an amplifier whose output is in Phase with its input once again the feedback and divider resistor will determine the gain of this type of amplifier a Unity gain buffer is an amplifier that has a gain of one this is also known as a voltage follower and takes advantage of the fact that the operational amplifier has a very high input impedance and very low output impedance Unity gain buffers are often used throughout op amp circuitry the voltage summing amplifier is an application from the op amps analog computer days the op amp will output a sum of the three different input voltages the feedback can be used to amplify this and effectively do a multiplication on the voltage another mathematical operation that could be done with an op amp is as a differential amplifier in this case the output of the amplifier will be the difference between vn1 and V in2 integration is another mathematical operation the operational amplifiers can perform and when performed upon a square wave it can turn it into a triangle wave you can also input a triangle wave into an integrator and come out with an approximation of a sine wave and the differentiating amplifier performs a differential operation on the voltage coming in you'll notice its effect on a square wave here an open-end comparator is a very common configuration for an operational amplifier a comparator has a reference voltage and an input voltage and if the input voltage exceeds the reference voltage the output voltage will go high or to positive VCC if it's below the reference voltage it'll go low or down to the ground level comparators are often used to interface analog Electronics to Digital Electronics a low pass active filter is a very common application in audio a low pass filter allows low frequencies to pass while attenuating high frequencies and it can be built as follows with an op amp a different configuration creates a high pass active filter a filter that allows higher frequencies to pass but attenuates lower ones and a multivibrator is a configuration with an operational amplifier can produce a waveform in this diagram we are producing a square wave whose frequency is determined by the value of CX and RX R2 and R1 can be used to determine the duty cycle and the amplitude of our Square wave now When selecting an operational amplifier you should go and take a look at the spec sheets as they'll give you all the information you need to know there's quite a bit of info here and some of it may be confusing so here are some of the key specifications to look out for the open loop gain of the operational amplifier defines the gain of the op amp without any feedback now an ideal op-amp would have an infinite open loop gain in the real world values typically range in twenty thousand to two hundred thousand or even more now keep in mind that the maximum output that your operational amplifier can give is going to be limited by the power supply voltage and not the gain the input impedance of the op amp is defined as the ratio of the input voltage to the input current impedance is a factor that is measured in ohms an ideal op-amp would have an infinite input impedance and real-world values for op-amp input impedance are typically several magomes meaning op amps won't load down this driving circuitry the output impedance of an op amp is also an important specification an ideal op-amp would have a zero output impedance in the real world the values are typically about a hundred to twenty thousand ohms the gain bandwidth product or GBP is a very important specification as it refers to the frequency response of your op amp now an ideal op-amp would of course have an infinite bandwidth the bandwidth of the op amp is limited by the gain bandwidth product and this is defined as the bandwidth with an open loop gain of one in the real world op-amps typically have values from 500 kilohertz to 20 megahertz or more the offset voltage is the output voltage when the difference between the inputs is zero an ideal op amp would have no offset voltage in the real world the values typically are one millivolt to 10 millivolt and this is an inaccuracy in the op-amp some operational amplifiers have an offset pin to allow adjustment of the offset voltage op amps are available in several different packages including dip and surface mount you can get single dual or quad op amps in the same package op amps are available using both single and traditional dual power supplies you also might see the term rail to rail designs these are op-amps whose output can go all the way to their VCC on most OP amps the output is slightly less than VCC unless it is specified as being rail to rail so now let's take a look at a couple of op amps and put them to use now here are a number of op amps that I got out of my parts drawer and each one of these is unique in its own right some of them are single op amp some are dual some are quad uh there are op amps here that are single Supply and there are dual Supply op amps as well now all of these are in dip or dual inline packages of course you can get op amps and other packages but for experimenting the dip package is what we'll use because they fit into a solid spreadboard now I'm sure you've probably worked with them before but if you haven't on a dip package there is usually a knot over at the front and quite often a DOT like you'll see over here and that indicates pin one so when you're orienting things that's the way it is and they'll be numbered one two three four down this side and then they'll go five six seven eight up on the other side and of course for a 14 or 16 pin package the number follows accordingly and so let's take a look at the character heuristics of some of these operational amplifiers the lm324 is a very popular quad operational amplifier this device uses a single Supply and can handle 32 volts maximum VCC the lm324 is used in a lot of equipment especially because of its low low price currently this retails on digital key for 40 cents per unit and so when you consider you get four op amps in it they work out to about a dime per op amp the ne5532 is another very popular operational amplifier this is a dual op amp and it uses a dual power supply each power supply can have a maximum of 15 volts this is a high performance operational amplifier with very low noise and Distortion so it can be used in audio equipment designs another popular operational amplifier is the lm358 it's also a dual op amp and has essentially the same pinout as the ne5532 however the lm358 has been wired to use a single power supply this is a very common operational amplifier and as its power supply can range from 3 to 32 volts DC it can also be used to interface analog and digital circuitry the tl072 is a dual operational amplifier that uses dual power supplies this is a very popular audio amplifier for Audio Designs as it has a very high GBP and a very high slew rate and very very low noise and distortion the ca3140 is a single operational amplifier that uses a dual power supply and has a maximum GBP of 4.5 megahertz the ca-3240 is the same operational amplifier in a dual op-amp pack these op-amps are often used in automotive and Industrial designs as they incorporate both moss and bipolar transistors for a very high input impedance and a very high current output capability the mcp6002 is a dual operational amplifier that uses a single power supply and that power supply has a maximum of only 6 volts it has a one megahertz DBP the mcp-6022 is the same operational amplifier with a much higher GBP because of the voltages these operational amplifiers use they have been designed to be used with logic circuits as they're perfect for both 3.3 and 5 volt logic they also use rail to rail input to Output so they can swing all the way up to their power supply voltage they're very low noise and Distortion and they consume very little current okay enough of the op amp Theory let's put some of it into practice we're going to take an op amp and put it onto a subtle as breadboard and wire it in a number of different configurations so we can see how these building blocks are really created now the op amp we're going to be using is the ne5532 which is a very common operational amplifier it requires a dual power supply but don't worry about it you can just use a couple of nine volt batteries for these experiments so let's see how the ne5532 is wired up and then we'll proceed to use it in a number of basic configurations I'll be basing all of my experiments around in any 5532 operational amplifier this is a very inexpensive and easy to obtain device this is a dual op amp and it contains two operational amplifiers that are wired as follows pin 3 of the device is connected to the non-inverting input on amplifier 1. pin 2 is connected to the inverting input on that amplifier and pin 1 is connected to the output of op-amp 1. pin 5 is connected to the non-inverting input of amplifier two pin 6 is its inverting input and pin 7 is the output of op-amp2 the positive end of the power supply is connected to pin 8 and the negative end to pin 4. note that there is no connection on the op amp for ground the positive and negative power supply for any 5532 can be up to 15 volts at a very convenient way of powering these for our experiments is just to use two nine volt batteries connect the positive side of one of the 9 volt batteries to pin 8 which is the positive VCC and connect the negative side to pin 4 which is the negative VCC the remaining two battery terminals are tied together and this is our ground Point again there is no ground connection to the ne5532 we'll be using this basic circuit with all of the different configurations that I'm about to show you now the first configuration that we'll examine with the ne5532 is obviously the simplest configuration there is and that's the unity gain buffer you'll notice that in this configuration the output of the op amp is fed back into its inverting input and that the input to the op amp is fed into the non-inverting input wired like this the op amp will have a gain of one so what goes in is exactly what will go out and you might think that this is a pretty useless circuit but it actually is not the unity gain buffer is also called a voltage follower and it can be used to take advantage of the fact that the op amp has a very high input impedance and a low output impedance if you want to mix several signals together you can precede each one of these with a Unity gain buffer as though not to overload an input the unity gain buffer is a circuit that you'll see used quite often in op amp designs and so here we have our first experiment the voltage follower and of course the very simple circuit that it is uh you can take a look at how I've got it on the breadboard I've got my two batteries each going to the different rails and I've also got a jumper over here and that connects the negative of the positive supply to the positive of the negative Supply if that makes sense to you and that is the common ground so just make certain that you realize that on the bottom over here the red is actually a ground and the blue is the negative voltage otherwise it's a very simple circuit just wired up with a few jumpers when you're working with analog Electronics on a subtle as breadboard you will find out that the breadboard does pick up a little bit of noise Etc now these breadboards I have on the bottom of them they have a little aluminum plate that's supposed to help seal them but since it isn't grounded I don't know if it's working or if it's even adding to the problem but you try to keep all your leads as short as you can if you using resistors and capacitors try to use those to make the connections without any additional jumpers just so you get a more stable circuit so if you take a look on the oscilloscope you'll see what we've got are two sine waves the yellow one on the top is the input and the blue one on the bottom is the output and of course they're exactly the same and that's what you would expect with a voltage buffer it just has a gain of one so what goes in is what comes out and of course the high impedance input can be used to buffer sections within your design probably the most common configuration that you'll see in op amp used in is as an inverting amplifier you'll see this used throughout audio equipment designs for example now this is how we're going to wire our ne5532 up as an inverting amplifier and we'll need two additional components an input resistor that's labeled as RN and a feedback resistor that's labeled as RF and both of these resistors in our case are going to be 1K now you can see from the formula here that the gain of the amplifier depends upon the ratio of these two resistors so with each of them being the same value our amplifier will have a gain of one if you want to change the gain of the amplifier you can do so by altering the values of the resistors and it is common to leave the value of R in in place and change the value of the feedback resistor RF if you wish you could use a potentiometer for RF instead of a fixed resistor so you could have a variable gain amplifier so let's wire this up and test it out now here's the demo of our inverting amplifier I'm applying a one kilohertz sine wave and that is the yellow one that you see over here on my a channel and the output channel is this one over here and as we can see the output has been inverted 180 degrees thus an inverting amplifier but otherwise it looks very good it's a very nice sine wave and again this is one of the most popular configurations of an amplifier that you can have using an op amp now the opposite of the inverting amplifier would of course be the non-inverting amplifier an amplifier whose output is in Phase with its input and this is how we would wire up our any 5532 as a non-inverting amplifier note that we're using the same two components the same resistors as we did with the inverting amplifier and that once again the gain is dependent upon the ratio of the values of these resistors as with the previous design you could change the feedback resistor if you wish to change the gain of the amplifier or you could use a potentiometer to build a variable gain amplifier I should point out that the formulas I'm giving you for gain are actually approximations because true formulas for amplifier gain need to include the impedance of both the input and output devices but for most cases these formulas should work fine for you to calculate the gain of your op amps so let's wire up our non-inverting amplifier and test it out and so now we have our non-inverting amplifier demonstration as you can see it's pretty well the same as the inverting amplifier with one obvious difference the output signal here is in Phase with the input signal so it has not been inverted and between inverting and non-inverting amplifiers you can pretty well control the phase of the signal throughout your design and it's not uncommon to use a combination of both of these in an audio design or in other op-amp circuitry now the next circuit that we're going to look at is also a very commonly used audio circuit and that's the low pass active filter this is a filter that will allow low frequencies to pass while attenuating the higher frequencies and this one is a very simple filter that attenuates at a rate of three decibels per octave we can calculate the frequency that it operates as by using the formula in the corner and you'll see that with the values that we have here it'll cut off at about 15.92 Hertz now you can change the frequency of course by changing the value of both the resistor and capacitor and in practice it's easier to change the capacitor to a fixed value and then trim the value of the resistor so let's wire this one up on the breadboard and check it out and so here's our low pass filter demonstration hooked up and uh visualized on the oscilloscope once again now a low pass filter of course will attenuate higher frequencies so right now we have a one kilohertz sine wave being fed into it the top waveform the yellow one is the input and the blue one at the bottom is the output so let's increase the frequency up a little bit we'll go to two kilohertz and you'll notice the bottom has started to attenuate and as I go higher in frequency top stays the same but the bottom goes down and so now we're at 10 kilohertz over here and you can see it's quite a bit less than if I back off to one kilohertz and so our filter is working now a simple filter like this only attenuates at about three decibels per octave but you can build more advanced filters that can attenuate at a higher rate or a sharper rate using the same basic circuitry that we just used over here now if we exchange the position of the capacitor and the resistor in our filter we can turn it into a high pass active filter a filter that allows higher frequencies to pass while attenuating lower frequencies once again the formula for the filter is essentially the same and rs has a crossover of 1592 Hertz now high pass and low-pass filters can be used to build things like tone controls equalizers crossover networks and to eliminate noise in circuits so they're very useful things to be able to know how to construct so let's wire this one up on our breadboard and check it out and here's a demonstration of the high pass filter which of course has the opposite effect of low pass filter the higher the frequency is the more of it it will permit through and low frequencies will be attenuated now once again for the demo the input waveform is the top one and the bottom one the blue one is the output and we're at 500 Hertz right now we're going to go up in increments of 100 Hertz this time so that you can see it and take a look at the level on the bottom as I increase the frequency so I'm going up in frequency now and as you can see the level is increasing the higher I go in frequency and now I'm at five kilohertz and the level is quite a bit higher I'll go back down so you can watch the effect in reverse and so a high pass filter basically just lets high frequencies through and attenuates the lower one and again this is a very simple filter three decibels per octave but you can Cascade these to get a sharper filter now in our final basic experiment we're going to use both of the op apps in the ne5532 and we're going to wire the first one as a multivibrator that'll produce a square wave the frequency of our Square wave is going to be determined by capacitor CF and resistor RF and so you could use a potentiometer for RF if you want to make a variable frequency oscillator resistors R2 and R1 will determine both the pulse width and the amplitude of our Square wave we're going to take the second op amp in the ne5532 and wire it up as an integrator as you recall an integrator performs a mathematical integration on a waveform we'll be using a value of 10K for R3 100K for R1 and C1 will be using a hundred nanofarads connect everything up and connect it to the square wave oscillator that we created earlier we can then monitor both the square wave and the output of the integrator which should be a triangle wave and here's a quick demonstration of our waveform generator and as you can see the top waveform is the square wave and the bottom one is the triangle wave the square is tilted a little bit at the top but the triangle wave is just about perfect and actually the tilting on the Square could probably be fixed is by adjusting the capacitance of my scope probe that may not be exactly accurate and so it works very well as a generator it's generating a frequency now of 1.88 kilohertz but of course you could alter that frequency by changing the resistor and capacitor values so if you need to generate a waveform an operational amplifier is actually a great way to do it now although there are analog circuits operational amplifiers can also be used to glue together analog and digital circuitry and there's a couple of methods they can use to do this one method that we've used before is to run an op amp as a comparator and use the comparator with a digital input pin on a microcontroller another thing you can do with an op amp is to use it as an amplifier to amplify the signal for the analog to digital converter and that's what we're going to do right now we're going to take an op amp and use it to amplify a very small signal and read it with the a to d converter on an Arduino Uno so let's go and see how we hook that up and then we'll put it to use now here's the circuit that we're going to be using to amplify the signal for our Arduino and we're building our amplifier around an mcp6002 op amp this op-amp is an excellent choice when you're working with digital circuitry as it is a single Supply op amp and it has a maximum Supply voltage of only 6 volts it works perfectly with 3.3 and 5 volt logic so again it's ideal for working with digital circuitry now what we have here is essentially a classic amplifier design you can see the feedback loop and the light blue up there the capacitor across the resistor is just for stability and to prevent it from going into oscillation the 100K pot you can use to control the gain of the amplifier and the output of the amplifier you'll also notice is a 220 picofarad capacitor across it just for a little bit of noise reduction now the input has a 100 nanofarad capacitor you can see it on the yellow on the left side if you were going to be amplifying DC voltages you can eliminate the capacitor and disconnect them directly but I've got this set up so that you could use audio voltage voltages from something like let's say a microphone for example otherwise it's a fairly basic circuit note the 2.2 microfarad capacitor that sits across the 5 volt and ground line you want to get that capacitor as close as you possibly can physically to the chip ideally you will straddle the chip with that capacitor and the function of that capacitor is to take some of the noise that might be on the line remember you're sharing 5 volts with an Arduino and microcontrollers in their peripherals can sometimes put noise onto the line now after you've got this all wired up in the breadboard you'll need to hook it up of course the Arduino and the hookup is very simple the power supply for the circuit the 5 volts will connect to the arduinos 5 volts the ground will of course connect to the arduino's ground and we're going to feed the output into analog input a0 and so once you've got that wired up you can feed a signal into it and run a bit of code and look at it with the Arduino so let's go and do that right now okay here's our demonstration of the Arduino with the op amp amplifier and you'll notice I've also added the signal generator and an oscilloscope to the mix right now now the signal generator is currently giving out a two kilohertz sine wave at half a volt and it's being Amplified by the amplifier uh what I've got the scope set to here right now is one bolt per Division and so I've got just about a full output over here it's amplifying just about 10 times now I'm going to reduce the level of the input over here and now we're at point one of a volt and we still got about a one volt uh sine wave over here I'm just going to play at the gain control a bit just to see the effect that has and over here I can get it so high I can clip it right now if you can see that and I can also adjust it down so I've got a lot of gain over here a lot of potential gain this is a 0.1 volt signal that I'm getting in here and I'm amplifying it almost to the full Voltage right now now if we take a look at the Arduino side of things the sketch is very very simple we start off by defining the pin that we're using analog pin a0 and a variable just to hold the value of that in the setup we'll set up the serial monitor that's all we do and then in the loop we're just going to do an analog read to that pin assign the value to that variable and then we're going to do a Serial print lid of that variable to the display and then we're going to delay for 50 milliseconds and do the whole thing over and over again and actually it looks better running on the plotter which is what I really wrote it for so let's put the plotter on and as you can see on the plotter you can see we do have a representation of our sine wave and the level is much much higher than you would expect from a point one of a volt signal so this is a really great way of amplifying and extending the analog to digital converter not just in an Arduino Uno but on any microcontroller because this op amp will work fine with 3.3 volts as well it's got a very good frequency response it's audio capable so you could use it with a very high quality analog to digital converter and also there are two op amps in the package so you could actually build a second circuit and amplify a second one of the a to d inputs and really add a lot of Versatility to your projects with an op amp and a microcontroller now if I gave you the task of Designing a light sensitive switch one that would turn something on or off based upon the absence or presence of light chances are you would probably start thinking about using a microcontroller with perhaps an ldr or a photo transistor on it and while that will certainly work there is a much easier way of doing this and that is of course to use an operational amplifier we're going to build a small light sensitive switch with an op amp that's just going to control an LED but you could extend it to user relay or a power transistor to control something else the best deal is that this entire design is going to take about two dollars worth of parts and no programming required so let's go and take a look at the hookup for that now here's the schematic for our light activated switch and we're building this around an lm358 op amp the lm358 is very inexpensive and commonly available device and it has an advantage in that it can work off of a single power supply so we're going to power everything with one nine volt battery now the output of the lm358 is going to a 220 ohm dropping resistor and then to an LED so we're just going to be turning an LED on and off but of course you could change this for a relay or a power transistor to drive something else now essentially what we're doing here is running this as a comparator with a voltage divider consisting of the 210k resistors attached to the inverting input on the non-inverting input we have another voltage divider which consists of the light dependent resistor or photocell and a 20K potentiometer you can adjust the 20K pot to adjust the trip point over here so this is a very simple circuit let's wire it up and give it a test and here's our light sensitive switch you can see the LED is on right now and if I go and cover the photocell the LED goes off and so basically it's being triggered whenever it sees light now of course the LED is just an indicator you could replace the LED with a transistor and a relay to drive something if you wanted to there's also another trick you can do with this so let me show that to you right now I'm going to disconnect my LED and connect it up another way I'm going to now put the anode up to the positive power supply instead and now what we've got is the LED is off if I cover the photocell the LED goes on so we've got the opposite Arrangement right now it's detecting dark instead of light so you can wire it up either way that you want to which is pretty versatile and as I said if you want to tie a transistor or a relay onto the output you could drive something else so here we have a photoelectric controlled switch that is not dependent upon a microcontroller in a very simple and inexpensive thing to build if you need something like this this is a great way to go now as you've noticed many operational amplifiers require a dual power supply a power supply that has both a positive and a negative component in reference to ground and you may not own a dual power supply my workbench supply for example is just a single output power supply but there is a converter that you can build to convert a single Supply into a dual Supply and the converter is based around an op-amp so let's go and see how easy this is to wire up and convert a single power supply into a power supply we can use with operational amplifiers now here's the circuit for our power supply converter and this is being built around in any 5532 op amp you could use another op amp if you wish providing it is an op-amp made for dual power supplies I'm also using two output transistors a tip 31c and a tip 32c now you could use different output transistors if you wish the key here is to use complementary transistors and npn and a PNP transistor that have otherwise the same characteristics the tip 31c and tip 32c are capable of handling three amperes of current so we can power something with up to three apps here although if you're going to go anywhere near the current rating you should probably put a heatsink on those transistors if you wish you could substitute a tip 41c and 42c and go to 6 amperes you'll also need a couple of 100 microfarad filter capacitors for the output and these need to be rated at at least the supply voltage so I would rate these at 35 volts or more now the operational amplifier has a voltage divider on the input that is made of two 10K resistors and that's being applied to the non-inverting input and the inverting input is just taking feedback from our reference or ground point on the output and it will adjust the operational amplifier if the op amp finds itself going at a different reference point and this will keep the voltages regulated on the output side so it's actually a pretty simple circuit to hook up make sure you've got it all hooked up correctly though because you are dealing with your power supply voltages so let's put ours onto a breadboard and check it out and see if we can drive another op amp circuit with our single to dual power supply converter and so here's a demonstration of my power supply splitter now I've got it connected to the square and triangle wave multivibrator that we created a little bit earlier so I'm driving one of our circuits with this circuit I'm using my bench power supply and it's giving out 20 volts right now and it's important to note that the bench power supply has a floating output in other words the negative side of the power supply is not connected to ground and that's very important if this had been connected to ground I would have literally shorted everything out when I connected my oscilloscope up over here and we certainly don't want that to happen but otherwise this is the breadboard with the splitter on it I think if you look very carefully down here you'll see the two power transistors and it is powering this circuit here and as you can see from the oscilloscope it is indeed working we've got the square wave and the triangle wave now I've got a multimeter over here and we'll measure a couple of voltage points here is the positive voltage that right now the multimeter is tied to ground and I've got 9.98 volts I'm not sure if you can see that and I'm going to go over to my negative side right now and I've got negative 9.96 volts so it's regulated pretty well now as I said earlier when I showed you the design if you wanted to you could also put a couple of three pin voltage Regulators on the output deregulate it even further but it actually splits the supply pretty well so this is a great solution if you need a dual power supply for your op amps and you don't have one just use an op amp to take a single power supply and make it into a dual one and so this concludes our look at operational amplifiers I do hope that you enjoyed the video and more importantly I hope it's opened up your eyes to the fact that not everything has to be built around the microcontroller you can build a lot of useful circuitry and projects around analog components like operational amplifiers now if you want to get some more information about op amps or if you want to get the circuits that I use today you will find all of that on the article that accompanies this video on the drumbotworkshop.com website and there's a link right below the video to that article when you're on the website if you haven't yet please consider signing up for my newsletter it's not a sales letter it's something I send out now and then to let you know about things that go on in the workshop because sometimes things do go on in the workshop and the newsletter of course is absolutely free another thing that's absolutely free is a dronebot workshop Forum so if you're having a problem with one of your op-amp designs get on the Forum there are a lot of great people on the forum who can help you out with your electronics projects and finally if you haven't yet please subscribe to the YouTube channel I make videos about Electronics microcontrollers programming and I think you would really enjoy them and all you need to do to subscribe is to hit that little red subscribe button that you'll find below the video and if you also hit the Bell notification you will get notified every time that I make a new video assuming of course you enabled notifications in your web browser and with that said please take care of yourself please stay safe out there and I will see you soon here in the dronebot workshop goodbye for now [Music] thank you [Music]

Channel: DroneBot Workshop

Views: 118,608

Keywords: op-amp, op-amp tutorial, op-amp basics, operational amplifier, op-amp arduino, op amp, op-amps, non-inverting amplifier, operational amplifiers

Id: _HHxV-7alwE

Length: 44min 20sec (2660 seconds)

Published: Mon May 15 2023