 Hey there YouTube Okay, I am this is a needs musting Basically, I need this board and I got a Circuit protection this is what I had to do a little while ago and I wanted to have a little look at some different types of circuit protection. So I built four here We got a single diode and This will work on the basis of if you get the connection the right way round it will work If you put the connection on the wrong way around like if I power this the wrong way around it won't work So you've got five volts there in a DMM We're gonna connect some voltage first of all, I'm gonna connect it the right way round That's a man The five volts No current being drawn and we got 4.8 there Okay Now of course depending on the sort of amperage you may want to put through this It's gonna be depending on the size of diode that you have This is just for demonstration It's not having any current drawn through it. So it doesn't really matter if I Take this off and reverse polarity connection Make a reverse connection. It's still five volts no current draw But that's what we get As an output and if I just disconnect that Really no difference whatsoever. So that works. That's effective. You've got a you've got a voltage drop low and that's something to keep in keep in mind and you've really got a Back in the old days of the CB radios when I used to help somebody in a CB radio repair shop This was always called the idiot diode That would be a thing that a lot of time people would blow when they reverse polarity CB radios to the power supply and they blow a diode inside That's what my friend likes to call it. Anyway, so We can take those off there now on this one this is It's all better circuit in a way, but then for the what I wanted not the reason I say that is I wanted to put some protection reverse polarity protection a little setup I've made for a friend and Damn it and Did it the wrong way around ha ha did anybody notice? Need output But I wanted them to see that you've got it the wrong way around just so he kept his mind on the business, you know Anyway, so basically what we are still five on some of their I get a bit sidetracked on Trying to concentrate off so they connect this up this way I can just get that straight on to the metal It's a lot easier doing this when you got two hands There we go, we got four and a half volts Oh Six there's still no car means wrong And the nice thing about this one is if you do get it the wrong way around because it's just Set up It doesn't really matter You put it the wrong way around look Can't connect that Push that out the way. I bet you missed all that because I forgot where the camera was looking And so we reverse the polarity And we've still got four point five. It was four point five six wasn't it? So that works okay again, it's one of those where you've got to make sure you size your diodes In relation to your circuit, so currently gonna be drawing Now the one that's what does beat these it beats them not for cost Or for simplicity or for just having the part in your box It beats it because you've got a lower voltage drop and you can and you know this this will carry some some ampage now You know, they're all different and so they're all gonna You know carry a different amount of ampage to allow it through But this is just using a p-channel MOSFET and It's sort of connected up in reverse to what you normally connected up to And this is as simple as it gets as well you've got a 10k resistor between the gate and the ground You have between the gate and the source Yeah, that is the Drain the power Coming in goes into the drain and then we come out the source and this is what I've got this where we're gonna Multimeter to and so there's a 10 volt Zener there and that's just the standards, you know protection between great gate and Source on MOSFETs anyway, but the Zener across But this will work. Well, well basically Black is the negative connection Positive to there There's no current draw at all. And the nice thing about this one lot Is you still got five volts? So and then if we do the reverse with clarity on here Basically, it would just shut off the circuit. I'm not putting anything through the circuit Don't join any current or anything Unless that for the reverse polarity, so that's pretty good. There's no voltage drop you see and Another reason why I thought this would probably be better for what I had in mind was just because Dealing with the 12-volt car battery When you get the voltage drop half a volt across these well When it comes to, you know, your 12-volt batteries and these guys out there know when it comes to charging these batteries and keeping These batteries you don't really want your batteries to drop below 12.5 because It starts getting into the area where it's becoming a problem to the battery You want to keep that thing above 12.5, you know And so having the voltage drop can be quite significant When it comes to those sort of things Or maybe I'm just talking Google gargah. I don't really don't know what I wanted to do was just see what the difference was I've just decided I was suggested this certainly works really well and it is great because four diodes bomb You've got yourself some really good volt circuit protection because it don't matter which way around you put the wires It allows You know, it basically is just gonna it's just gonna channel it through one way Anyway, it's always gonna come out that same point. So no matter which way around you connect it This one is slightly different This one uses what it calls. It's called an intelligent. I Just said it in such a way that sounds Negative, but I don't mean like that. It's just a bit weird when things Suggested to be intelligent Just put that in there basically What you've got it is you've got a PMP transistor and the NPN transistor and the PMP transistor It's set up to pass current by by having current pulled out of these base Okay Now in this example five volts where the NPN can pull a lot of current out of the PMP base and Consaturate it down to under a hundred millivolt Okay, I'm reading this. This is not coming out of my head The 3.3 k resistor which is here That limits the amount of base current to the PMP the 10k resistor which is here Yeah, the 10k resistor That provides a signal to the NPN to turn on when the V in power is correctly He's off the correct clarity and to turn off when it's backwards the four points so in Make resist that which is this one here So here I am making the video and I'm just explaining how this works and I Take a look in the back of my video thing and it's all frozen I can't actually turn it off. It won't turn off by the power button on the front. It's just frozen I don't know that's because we're in the middle of a storm or What's really going on? But that is frozen and I was just explaining about this and I will explain now that I was reading it Not just having it come out of my head I mean camera is frozen so I was going to do a little review on this And that's gonna be one of the first things I talk about why would this thing just want to freeze up? I'm telling you look it doesn't stop. I can press the button. It's absolutely no life. It's frozen I can press this power button on the front and just hold it Just like it's holding Still hold it in and click it Hold it in And click it. We should have something press the one on top which starts stops the video It's a bit weird because I'm trying to do all one hand so I'm holding this camera in this hand It doesn't do anything So what I've got to do with this now Is to I believe it for it to go dead or Take the batteries out the battery out and have to reset it all again To get rid of the date stamp and all that sort of crap So well that's good isn't it it freezes That's really helpful But just to finish off this video because as I said at the start of the one I'm on here And I really hope I get to keep the video because that'll be quite annoying Probably better leave it to the battery runs out. So I'm not quite sure what I've got to do there The other buttons on the sides don't do anything on it because I'm pressing those and Don't do anything. Look at the state of this one Hmm build another power supply this time using the LM338 two of them Voltage currently just right back to this so let's go over this again, so Basically what we've got going on here is we've got a PMP transistor is set up to pass current this one By having the current pulled out of his base The MPN can pull a lot of current Out of the PMP base and can saturate it down to under a hundred millivolts pretty good the 3.3k Which is this baby here Which is the limits the amount of base current to the PMP and the 10k resistor This one The 10k resistor provides a signal to the MPN to turn on when the V in is the correct clarity and turn off when it's backwards the 4.7 make Which goes from this positive To here, which is the base And 100k resistors help keep their respective or the 100k sorry this here help keep their respective Transistors help them turn off when they're supposed to be off and the IN4148 DIO protects the MPN transistor from damaging reverse base emitter breakdown And that's what I was trying to say and I was going to show you it working Back on was still a five volts over there And so I'm going to put it on the quick way around first or first of all, let me just I'm sure that we're gonna I need power out of here Leave my ground there. Okay just These up again for that. We can see that I'm trying to move on to this Let's get this one. It's worth paying it back slowly. We've already got two hands Okay, that's still frozen. Let's put the the ground on here No, sorry if it's all shaking Okay, so Now look, there's a little bit of current draw there. It's pulled it down 4.99, but we did have five volt there and Now I suppose it's warmed up a little bit maybe it's gone to zero So let's just do the reverse clarity make sure this sucker works so Not no current draw or anything That's the reading there So and if I take off one of the leads like to the ground There is a bit of a difference there when I connect up to the ground And again, you know, it's The amount of current you can draw through these is going to be sort of pretty dependent on you on the old transistor here And even though she's certainly want to heat sink It's been that much currently be pulling through it. I think that's It's not very high voltage. I think it's like it's 55 volts and So right about 30 amps or something. I'm not exactly sure it doesn't really matter. It's just a demonstration Just to show that it actually breaks a circuit and didn't pull any power or anything dodgy. So What would I say was the best that what it's like I Reconnaissance is you know for convenience ease of use and for low power stuff. This is great. Can't really go wrong with that Some of you want more power through it's got to be the MOSFET because it's got the pretty much, you know, very low voltage drop and Probably find yourself even Better MOSFET. I've got some good MOSFETs going actually with a 0.0.0 to RDS This one's probably a little bit more complicated. It's considered to be it's Where I've seen it on the website. It's the intelligent one. I'll show you the atrochromatic plot Very how you can see that. You have to pause it or something. It'll be a shaky Yeah, that's it. So bit of reverse polarity Now I need to whip all these off because I need this because I need to build my circuit for The building this power supply. Look at those capacitors Baby loo Tank capacitors brilliant right on game Cheers watching guys. We got this far