 Hello everybody and welcome back to my channel. This is the power-up. I've got my power supply pre-set up because that's what we're going to be doing here. What we're going to do from this because we need the dual power supplies. We need the positive 30 volts 33 to 35 volts and the negative. That's what I've got here is I've got my negative from this side and the positive from this side. They're connected together. You can't even see that. That's ridiculous. So they're connected together. Like this and this will give us our zero volts and then we have our negative side which is innocence and it's going to go on the back of this because that's what my power rows are. You've got one here and the other one on the other side here for the positive. That's going to connect it up for power. I've put this thing into a synchronous mode and let me just check the back for that again. I've been over. I did find a mistake and the mistake is a quite visible one. If you were to look back at the video and that is that this here was actually coming down. Oh crying out loud. This here was actually coming down from the base. The wrong side of the resistor there. Yeah, so it was coming down to the wrong side of the resistor. And what that meant was that I was getting quite a lot of voltage on the output there which is no good. So I corrected that. And that's what we want to be able to do. We want to be able to start applying voltage to this and keep an eye on the power supply. And if we see the current rising too quickly we know that we got an issue. So I'll start this off. With both of those channels going on and then I'm going to start just raising this voltage up. So we got one volt, two volt, three, four. We should now start seeing that the current going up too high if that's the case. So about 20 volts I'll do. And as you can see the current's not really doing the lot. So we can pretty much say that we don't have any type of short circuit or anything like that which is, you know, that's exactly what we want. Now our next test, because it's going to be done in stages like this, we need to have a little look and see what we got on the output here. And what we don't want to see is too much voltage. So in actual fact, because I was just going to leave those and we can use this one because we want it in the mini-volt range. And we just want to see what's going on on that, on that output. We're looking for DC at this stage. So it says 17 millivolts and if we were to go down like this, to zero, you watch those mini-volts go up. Can you see that over there? Just bring that a little bit closer. So those mini-volts go up. And as we can raise up to our desired voltage we see the mini-volts go down. And as we go up towards 30, as I'm pretty confident now there's nothing wrong with it. We're good there. Okay. So that's good. That's a good sign. We're going to wind it back down again, looks nice to do this. Now you can do this if you're using a transformer and your capacitors. Because this is my speaker output, by the way. This is to ensure that these two wires never touch together because if they do it's going to bust up the transistors. And that won't be any good at all. Now, so we know that there's no big issue going on there. And now what we want to do is just look for some, okay, we want to switch that thing on. We want to look for any dodgy noises on the output. So for that we need an input and we also need a speaker. So what I've done is I've just made, I've used XT60 connectors because you know I've got quite a few of those from the old drone stuff. And let me just switch this off for a minute. Just want to make this connection. We've got that from the drone stuff and it doesn't look like I can do much more of these types of drones anyway. This will go off in the middle of nowhere. And as I don't know a vehicle at the moment, that's not going to be happening anytime soon. Just checking those connectors are still on the back there. And so we've got our speaker connected. It's going into a 6 ohm speaker, which is okay because this is 4 to 8 ohm amplifier. And I'm just going to connect up here because here is where I'm going to be putting my inputs into. Rather than do it before, I was just soldering onto the capacitor. I've put actually little connectors on these times this time. So there we go there. And we have, I just get rid of that for the moment. I don't need that. And we have on the signal generator. We have our waveform generator. We have four millivolts peak to peak. So that's nothing at the moment. But if we just put the output on there, I'll just turn this on. We've got to start winding up that voltage again. I don't know if you can hear it already. I've got an eye-swordable tone there. If I just go into my amplitude, to my amplitude and start turning it up. Yeah. Then things are going to have to run with that at all. That sounds quite nice and healthy. Just back that off and turn that off. We can turn that off again. So that's part two of that. Let's wind that down. So I'm just going to disconnect this anyway because I don't need this on here now. It is a little bit of a heavy-duty connector. But I prefer it to be nice and stable like that than not. So I'm quite satisfied that that's okay. So now we want to check the bias current. And what we're going to do there, I don't know whether it wants me to put in a signal going in. I don't see why that's going to make any difference at this stage. Because we know that we don't have high millivolts on here because we've already tried that. And even if I turn it up, we saw what happened. It went down to about 16 millivolts, didn't it? Maybe they're talking about if you've got an output signal. So okay, let's just do that anyway. We'll just put this in here because this is the negative out and the other side's positive. We can just drop those now like that. And we can see on there, on the DC, no power on, way below. So we just put that power back on again. Turn this up. Yeah, and what we're looking for is our millivolt output on there. And there's nothing. You know, nothing to be concerned about. We go full blast. There's nothing to be concerned about there really. But why about if we put that output on? We don't have any sound, but we can see there that we still don't have a problem with it going up very high. We don't have any sound because the speaker's not connected. All right, so we can turn that back off again. I'm just going to wind that back down again because I just like the idea of just driving it up slowly. It's only because I, even though I'm pretty confident everything's okay, I still get scared as soon as I'm going to go wrong. Okay, so now what we want to be able to do is we want to be able to go between the collectors of both these transistors. And we want to make sure that we can get our bias current up. Now, what I normally do is with these, as I look at the current that's being pulled off here, and I tend to go up to around about, so like 50 mA, both sides, and then check and just see where we're at and then just take it up a little bit because then I can watch what's going on, which is what I prefer to do. So I'm going to do it like that. I'm going to take it up to the highest that I can take it to, which is 32 volts now on your, you know, when you're using a 24-volt battery, you can get 36 volts aside, and so it would have to be set a little bit lower. But that's the sort of thing you can do, you know, once you've got it, once you've, if you're setting it up on your bench with it, and then you can do that because you can just put a meter in series with one of the sides and you can keep an arm what's going on with it because this sets both sides. So you can see at the moment, now, this is going to take a little bit of time to warm up. So I'm just going to speed up that warm up process and it's going to take this up higher. Okay. And I'm going to get it on about 65, 70. That'll be, because it's on a little bit higher, that means that the whole process of it just warming up and getting those transistors warmed up. I don't know if you can see the little green lights on. You can barely see it, can you? You know, then I mean, it's not supposed to be a big bright light. Then I push it down. It's not supposed to be a big bright light. What it's supposed to do is it's there because it's allowing a certain amount of voltage across it because it's the green light. And it also, using that 22k resistor, only lets about one and a half amps, milliamps ring. That's why it's very dim. But as you can see, look from the power supply, you can see that current is raising. As I guess, as it warms up and it's letting more current through, that means these output transistors will get warmer. I'm going to start backing that off a little tiny bit. Not much, not that much, I'll do. This is a process that might take you five or six minutes. And if it seems like it's going to take that amount of time, I'll just, I'll have to just skip through a little bit of the video. All right, to save time. It shouldn't be taking too long. But the nice thing about it is, like I said, there was one mistake that I saw. So I corrected that. And we're good. We're good, I'm quite pleased. It's set out quite nicely. Set out quite nicely. And we don't seem to be, I'll tell you one thing that's nice to see is that we're not climbing too quickly. Which to me means that nothing's getting too warm too quickly. You know, current's not like shooting through this too quickly. So what I'm going to do is I'm just going to take a little look. At this, and we're just going to see what we get over here. And see what the actual, what the millivolts is. Now, it's supposed to be, you get 1.5 milliamps to a millivolt, right? So if we want about 75 milliamps on there, we want about 50 millivolts. Yeah, it doesn't have to be, it doesn't have to be exact. Somebody wants my attention. It doesn't have to be exact. But it's got to be, you know, sort of pretty close. 75 milliamps is a nice sort of quiescent current. So if I go through on here, what've we got there? We've got 50. Yeah, it's counting down 46. Now I can't leave those in there like that. We're on 78. So if I were to take that up just a little bit more, I think we're about in the ballpark where we want to be. The 50 millivolts, yeah? So I mean, that is okay. The way that is set, it's pretty much okay, but I'm just going to give it a little, no, I don't think I am. I'm going to say that's going to be okay, because once this has been warming up for another further few minutes, he's jumping about, are we? Because he wants my attention. Once that's, you know, as you can see, it's gone up 1 milliamp on the negative side of the channel. But once he gets there, I'm going to say that's going to be in the right ballpark, right sort of area, and we're good. This thing is ready for me to basically start doing some tests on it and see what sort of power we can get out of it and how clean it's going to be. Because we can't really do that with the way it's set up here. But we can do it in the next video. Guys, if you got this far, thank you very much. And thank you so much for being, you know, there through the entire like little mini series of this going on. One quick check, because we've gone up by a couple of milliamps, and let's just see if we are a bit closer to that 50 millivolt on here. Oh, let's make sure we get that plugged into the right one. So I'm going into the collectors. There we go. Look at that. 49. 49. And it's good for plus or minus, you know, five milliamps, uh, millivolts. It's not too bad. But that gives us about 70. It's supposed to be 75, but as you can see over there, it's saying it's a bit different. But by the time you're taking into account of, you know, accuracy and all that sort of stuff, it's just about there. But this is what I'd normally use. And let me just see if I can see it again. On the other one underneath my table, I've got one of these. And so I let it get, because here's the 100 milliamps, 200 milliamps, 400, 800. And when this thing kicks, it's bam, bam, bam, bam, bam. You're cracking across this one amp when you've got it turned up. But generally for listening, it sits about 80 milliamps. And that's when you can just listen to it in the room, quite happily. It's pretty good. But when you start turning it up, yeah, you start drawing a bit of current. And it will quite happily draw that one amp. Because if you think about it, it's sort of like 35 watts on the side, so you get about sort of 70 watts out of it nicely. And a 35 volts, 70 watts is one amp. 35 volts aside. So you've got 70 volts in one amp, 70 watts. Thanks for watching, guys. I'll catch you in the next one. Bye-bye.