Horrific LED tester that can literally kill you - (with scary schematic)

It's an LED

tester

, not just any old LED

tester

, but one of the cheaper ones, so I wonder how safe it will be, especially given that its mains is in an ungrounded box and it has this strange LED sticking out of it. a plug. the top and then two probes come out. I wonder what the cirage will be like, but anyway let's start testing it, so I'll insert the probes. I haven't explored this at all, we'll figure out together what voltage. this goes out and what's that about the current, they short circuit the current, well that's a bad start, really okay, I'll tell you what, let's see if we can find some probes that will actually fit unless I can unscrew them by complete, yes, I will unscrew them completely fine. that's even safer and we'll just fill it in like this, there we go, now it's connected.

Good start. Now I'll make sure I don't put my fingers near these probes and bring the appropriate LEDs to test. I will also try this, the instructions by the way say it is suitable for 3 210 volts with no adjustment required, current limited, suitable for testing an LED more directly and I think this is a small tester just for small LEDs and this part says pretty pleasant. Be careful with imitations, do not buy poor quality products. I'd say we already found one. Where is my corresponding little Chinese tester? So we'll connect this to the corresponding little Chinese tester.

I'll plug it in. I'll turn it on. No problem. Well, when is this LED here supposed to light up? I'm going to turn off the power here, I don't really trust it, uh, right, I don't know what that LED is. I tested it before and it was working but I didn't test it on this maybe it's just fried maybe the polarity is wrong let's just insert this into a tester or maybe I just haven't learned how to use it yet give me a second oh the LED It works, so God knows what. that clears it up, I have no idea anyway, let's just ignore this, so since that part doesn't work, let's turn on the power and carefully holding these wires cautiously, let's get an LED of the type that is designed to test, among others , It is designed. to test backlights on video panels and things like that, like LCD screens, and if I plug this in here, it will turn on, nothing will happen, what if I click on it like that, nothing will happen, click on it That way, isn't it great?

For starters, there's nothing great going on, good quality control right there, uh, let me take a test meter, stick it in and see if there's anything on these. This little Cheapo gauge has Croc Clips on Croc Clips that are already slightly melted due to an incident. so let's turn it over and put this here, set it to DC voltage, let's set it to 500 volts DC, turn it on, nothing, nothing, nothing that's even a little bit concerning, right? Does this make a good connection? Should I turn it over? No, I mean AC, so it won't make any difference, nothing true, I'll tell you what H shorty Pro, actually, this doesn't work very well, let's open it up and see what's inside and what it's supposed to do.

You should take these cables out as is. takes everywhere right now uh that's not really a great start to the video. I mean, on the other hand, it's a great start in the sense that everything went terribly wrong, everything is fine now, let's unscrew some screws and see if we can. find something interesting one screw two screws three screws I wonder if this is a tip with a clip on the cap on the top you just sit on it. I feel a little movement here which might be quite useful to see how this is all going ooh right Okay, there's an encapsulated module in here with a bit of heat shrink over it, exciting, oh the top of that doesn't break down, actually breaks down, this will allow us to see a little bit more, if it will decompress completely or if I will have it. a yeah, it's there, oh, you know what the LED is in series with the output, look, it would have been useful to know, it would have been useful to know, I'll tell you what we're going to try this again, now that we know what's going on.

I'm going to hook this. There will be a very loud clicking noise. I'll remove it briefly just in case it makes too much noise. Oh, he doesn't want to hook it again. He doesn't want to hook it again. Well, that will do. I should leave this hanging in a dangerous way, right, let's put red, not that red often means positive, let's put this LED here which is a little tacky. I wonder how many people have them and they didn't work. I thought it was flawed and just a shitty design, okay? So if I plug this in now and cut those wires, why does this have two positions?

If I plug it in now, carefully place them where it can't fry me and I turn on the power and touch them together nothing, turn that on, nothing, nothing, this is not going well, is that right? No, let's turn off the power again. What the hell? This is not good. Oh, you know what the red war is? It's going to positive, which means this LED would have to be upside down and I've probably blown it out. Will it still work now? This is simply precarious. This is just the worst start to a video, but also the best start to a video. a video sometime let's turn it on H oh the LED is flashing but now it's dead although it's not happy no it's h oh here it goes I've made it clear now this is working what happens in the other position of the decoy intensity yes , low intensity, sure, I'll tell you what we're going to push this and we're going to bring an LED here and we're going to put it on this LED, oh, that's pretty reasonable, we're testing it, how about just to see what the voltage is going to be? try putting it in one of these modules, just hot or neutral, oh god it's doing the whole thing, it should have a pretty high voltage, it says 1.2 watts.

I take it off at something that goes to zero, uh, sure, I'll tell you what, then let's do a little bit. electrical test. I'll cut the power. I'll put the little Cheapo meter back in and see what open circuit voltage is generated. We're going to set it back to 500 volts because I think it's going to be pretty high. I think they could be. telling poris about the matter up to 110 volts, so what will be the open circuit voltage? uh, 212 volts, that's what it's going to be, what the short circuit current is going to be, it's going to be 200 milliamps here, uh, 6 milliamps and I say like this.

It goes up to 27 milliamps, which is enough to give you a pretty significant electric shock. Not well? Both are enough to give you a considerable electric shock. Well, right now we have verified that this kind of work is so vague, especially the fact. They just poked it in the case, what are they doing? What was going through their minds? Anyway, let's explore the inside again. We've almost explored the inside, but I'll remove the heat shrink cover and we can try it out. First of all, I'm going to short these wires together just in case, yeah, that'll do.

Mhm, if I get a shock, I get a shock, no shock, okay, so let's cut some of the heat shrink. I have a horrible feeling. It will just be a capacitive dripper and will actually be quite electrically dangerous. I'll turn off that Pur PL. I hope it's dangerous. CU. You know what we do. We like dangerous things on this channel. It's what makes life worth living. oh oh oh oh oh, sure, I'll reverse engineer this, this doesn't look good. I'll reverse engineer this and we'll take a look at the circuits in a moment please, and let's summarize, just say if you have one of these units.

You may want to stop using it because it carries a very high risk of fatal electrocution. Let's zoom out on this, the incoming supply goes to two capacitors, two 220n capacitors in parallel with a 1 mega ohm discharge resistor, in case you feel a tingle in the plug it's the least of your worries, the probes are the part that will take away your tingle, there is a discrete Rec Fire jumper and then there are three resistors including the super high power mode which is a 3.3k resistor but the red band has changed color or so the fact that it is overheating there is a 33k resistor and a 1.2 megohm resistor oh okay let's look at the other side of the circuit board the layout is just as mentioned the two capacitors are in parallel with your discharge resistor, there is the Bri shoot with the wires and notice that the current here goes directly to the bridge as far as here is concerned, so fundamentally one of the probes is basically connected directly to the mains through of a diode and the small LED, so you don't want to be confident if you change it. polarity, these capacitors will still pass enough current to give you a terrible electrical experience, but the negative side goes to this common bus for those resistors which then go out to the different configurations of uh.

I didn't know there was an intermediate configuration. a low setting should say let me show you the

schematic

of the switch in the middle position uh basically it has a resistance of 1.2 megs. It's a low setting, but it's actually common to the others and just passes because it meant two. The position switch with off in the middle actually gives you three modes, so here is the incoming AC supply, it is not polarized, it is a non-polarized plug, you can plug it in anyway, there are two 220 fire capacitors n in parallel to give 440 nard, there is the symbolic gesture discharge resistor which is actually nothing special since it is attached to one of the probes anyway it passes through the bridge the fire passes through the small LED that it hangs from the front of the wires through a twisted hole in a connector uh I noticed that the positive wi is actually black so I took out the LED and thought Oh that must be for the test LEDs and put it with the positive on red and the negative in black, that was backwards, that's why it didn't work.

It doesn't work the first time, but that goes directly to the positive probe, um, and the negative goes through these resistors directly to the output through the 1 me 1.2 Mega resistor. Oh I'll just fix that 1.2 Mega resistor and you can change it to medium mode which is 33k or super Smokey resistor mode which is 3.3k where if you attach the scalar cable it will emit smoke inside and that comes out to the other great cable like this I looked on eBay to see if they still sell them, oh yeah. Yes, they are and, rather amusingly, let me zoom out here.

Amusingly enough, the listing even shows it with the little case removed because the probes don't fit. You have to remove the probes to put those things in. And there's the LED hanging. from the front, the one in series with you to stop you from dying, which won't cost £140, it's a bargain, um, for death, eh, I did a search and it said are you interested in more of these on eBay? and I said oh yeah, show me the others and I was like, oh yeah, we have a bunch of them, well, like 25 different listings appeared on that suggested thing that showed the same picture every time of a young girl, uh, exploring a circuit board with these.

Active probes refer to the mains oh China you and your electrical standards so there you have it if you have one of these I would recommend you consider not using it because even with an RCD some of the RCDs don't work . react very well to half wave DC uh half wave rectified means that's what this is putting out oh no, I also notice that there is no capacitor in that circuit diagram, that is also the reason why it seems like I have a fairly low voltage, uh, relatively speaking, I didn't get the full Mains Voltage when I tested it with a small meter because it was clipping the half wave DC and basically showing about half the voltage, but yeah, this is not a safe device.

If you've been using one for a while, you probably have. I was lucky, just keep in mind that if it's grounded and you touch the probes or circuit board while you're testing it, there's a risk of fatal electrical shock, but other than that, it's an incredibly simple LED test design. and interesting third world. fascinating but fascinatingly deadly