 Hi everybody, I've got three amplifiers here, this one here, this is a LM386 a little eBay £1.14 be cost, and it's a little eBay variation of the LM mate the LM, god damn it, 386, 386 sorry, this is also an LM386, this is one that I've built, the immediate differences between the two ICs is that this LM386 is not a Texas Instruments, whereas this one is, you can see that in there, that is Texas Instruments, and here we have got a TDA 7267, all three are little mono amplifiers, again this one I've put together, this one I've put together, this is a little radio so if I'm working on it, ignore that, don't see that at all, pretend it's not there, and so what I did was I gave them all an input of a 1 kilohertz sine wave and at various different voltages, you can see that, so we got 6 volt, 9 volt, 12 volt, 15 volts, and these are the numbers that came out, that's 6 volt, I don't know why but it sounds like I'm going quite, it's because I'm looking at the monitor screen for the camera, just to make sure that I've got any information that we need to see, but anyway 6 volt, 1.25 RMS, 3.6 volt peak to peak, and that gives a 0.19 watts, 9 volt, we got midi-colour 4 watts in power, the 12 volt, just over half a watt and 15 watt, we're going to 0.65 there as you can see, and I've not actually done the other ones yet, I did them together, but I'm going to do that in a moment, I just wanted to show you what it actually looks like on the oscilloscope when you're measuring, I don't know if you can see that very well, I hope, and now I'm just going to put the power on because I've actually got, oh I'll show you, I've actually got this one connected up look, so here's the, here's the one kind of upside wave, it's coming through this white here, it's coming to the input on here, this is connected to the power supply in the background there, the 15 volts there is for the, it's for this, and we're going to go straight in for 6 volts when I switch this one on, which is then a little amplifier, we're not going to hear anything because the output is connected to this 8 ohm 100 watt dummy load and it's also scoped at that point and it goes up to the oscilloscope here, so I'm going to switch on the power and then you can see the sine wave, you can see the bottom left, I don't know how about you can see this, oh by a decent camera or I can, so what we've got there is a pretty clean signal and if I use, as you can see, you can see that, the frequency there, you can see the voltage now if I use the volume control down here on the little amplifier I can then start adjusting, you can see that's clipping and that's not at full power, all we're going to do is we're going to take it to just as it clips, see there it's too much, that'll be distortion about the, I would say, and that's at 6 volts, that's my, that's my M386, now at 6 volts on the eBay version we get 902 millivolts, but at 6 volts on this one, we're getting 1.14 volts and I have noticed that the TI chip is better, you can turn it up, you can get extra out of it, get more power and bang for your money out of it and like I said I've done that with these three chips, the only thing I haven't done is just quickly go in the map, using the calculator of course, because we're going to take that, like in the instance of this now, 1.14 volts square root back and divide it by 8 times and that will give us, let's turn on the calculator, I should do that, give us this here, so I don't know if it's going to focus in, so we go 1.14 volts, yeah you can see that good and then we're going to square root that and divide it by 8, so we get 0.1624 watts, which isn't a lot really is it, but that's at 6 volts, that's at 6 volts, if I put that back there, okay for all one, if I put that back there like that and then I'll turn this little thing up to, I'll just go straight up to 12 volts, okay, so there's no real change there because I've not changed the volume on there, on the little amplifier, but I'm about to start turning the volume up now and as you can see the amplitude gets bigger, I'm not clipping as yet, so I'm around 2.22 volts already, I'm just going to turn that down so we can carry on going up, oh look we are clipping just there, so we've got about 2.57 volts at 12 volts, which isn't too bad, the little kit, the ebay, yeah because this is the ebay lm386 and the one that's actually on test is the one that I put together, the ti, as you can see plus 12 volts there we get 1.99 volts rms, but we get 2.57 with, I don't worry about this, that's just in there, let me let me change the view there, 500 millivolts, yeah I'm sorry I should get carried like that, so as you can see you know there's that one, that one kilohertz signal and there's nothing really happening, either side of it, the sinusoidal wave is nice and clean, we turn it up a little bit more, you can see it's clipping top and bottom, that'll be the distortion and as you can see here it's picking up extra harmonics, the jury unwanted, we turn it a bit further, it'll happen even more, oh I'm turning the wrong amplifier and it's nothing's happening on the screen of course, it'll happen just more or more as you can see and they get worse and worse, that's absolutely a hideous sound but I'm sure we don't have to listen to it, that's pretty much no distortion whatsoever, and I said 2.69, 2.7 volts rms, okay so I think so I'm going to do the math now for these and look at the calculator later of course, I'll just put in the results of those and see which one comes out best because they're all rated around about the same thing, the TDA 72.67 is just about the same as the AM386 and then there's just two different AM386s