Viewer Question: How Does A Single Supply OpAmp Work

hey what's happening guys I'm gonna try and answer a question I get asked a lot today and that's about setting up an op amp as a single Supply device so first of all let's go over and talk about your op amp here just quickly we have a non-inverting input we have the inverting input we have the output we have the positive voltage and the negative voltage so to set up our op-amp in the traditional standard way we would need two voltage sources and generally for these op amps uh 741s tl-82s 72s generally run them about 15 volts and this will be minus 15 volts and then we need to put a ground to each one of these real simple and then we'll take our positive voltage and that gets connected to the positive voltage input our negative voltage gets connected to the negative voltage input we'll do a uh a standard inverting amplifier foreign so our not our non-inverting input goes to ground our inverting input needs an input resistor in this case we'll go 220 ohms and then we need a feedback resistor and in this case oops we'll double it basically we'll go 470 ohms and that should give us a gain of 2.13 so basically we're going to be able to double our input and this feedback comes right back here goes to the inverting input and then we need our AC signal so in this case we'll just throw it right here needs a ground of course and we'll do it about six volts at a kilohertz and that connects right here and then we'll put on some meters so there's our positive voltage input our negative voltage input there's our AC input and there is our output so if we run this you can see we're obviously getting our oscillations and if we split this out here's our green this is our positive voltage input at 15 volts down here is our negative voltage input at 15 volts the dark blue is our our is our signal input and as you can see here it is right at about six volts and then the purple here is our output and that's coming up to just about 12 volts so there is your simple foreign super easy super simple all right let's start killing some stuff you don't have to watch this part okay so I've left our feedback loop in here so this is our amplifier section what we need now is our voltage section so we're going to do a single Supply and we'll make it 15 volts just like before now here's where things are going to get interesting what we're going to need to do is we're going to build a voltage divider like so foreign voltage divider to ground and this is where our non-inverting input goes let me connect the rest of this up here like so now here's where we've made the change our non-inverting input previously was going directly to ground which was the halfway point between our positive 15 volts and our negative 15 volts but what we're going to do now is we're simply going to ground our negative input and because this point right here is halfway between here so it's seven and a half volts this is now at the halfway point so you see how it's the same it's the same but it's different halfway halfway so now we'll put in our AC signal and we'll do the same thing we'll put in six volts get a ground on there and we'll connect everything up and we'll put on some meters so there is our VCC here is our half VCC here is our AC input voltage and here is our output voltage and let's start the party so now if we look here you see this green line this is our voltage off the battery 15 volts this pale blue line is our halfway point seven and a half volts so that's where our ground was previously so this has now taken the place of the ground so here is our input voltage and here is our output voltage you can see our input voltage is swinging between six volts negative six volts positive and up here we are swinging between 10 volts and just about 15 volts so what we've done is we've offset this and that's the one place you're going to have a problem if you're trying to use this type of a circuit with an audio signal because now you see we have a seven and a half volt offset that you're going to need to take out of there but if all you're interested in is running your op amp with a single Supply it's pretty easy that's how you do it so I've got 23 separate op-amp videos in my basic electricity and electronics playlist so do me a favor check them out and if you have any more questions you know you can either put them down below or you can send me an email to Arduino zero one six nine at gmail.com that's it I'm out p

Channel: learnelectronics

Views: 4,221

Keywords: learnelectronics, electronics, op amp, opamp, tutorial, amplifier, viewer question, work, operational amplifier, electrical engineering, op-amp, circuit, single, dual, supply, lm741, tl082, jfet, inverting amplifier, dc offset

Id: luyEkYFPKJM

Length: 9min 17sec (557 seconds)

Published: Sat Feb 04 2023