 Greetings, electronics friends, and welcome to my childhood. This funny blue suitcase is actually an enormous electronics kit. This is from the Philips company, which you might know from, it's a Dutch company, and this is the Electronics Labor or Electronics Laboratory, EE2000. So Philips came out with, in the 70s and the 80s, a whole bunch of electronic engineer, basically laboratories or experimenters kits. Kind of the equivalent of the Radio Shack 201 kits, but this was made by Philips. And as you can see, it's very nicely presented. It comes with two manuals. And when I got this, I was about seven or eight years old, maybe nine years old, or so. And even at that time, I really liked electronics. And my father, who made many trips into Europe, and especially West Germany, at the time, of course, it was West Germany, got this for me and brought it home. And I was fascinated by this whole thing. So no sooner did I open the book that I realized that I couldn't understand a single thing that was in the book, because it was all in German. And my father didn't speak German. So anyway, I had these, and I sort of tried to put the circuits together, but I didn't really understand what I was doing, and I didn't even understand. So each experiment basically has a schematic and also a layout on how you put the thing together. But I didn't even understand values of resistors and capacitors. I mean, I knew what a resistor looked like. I just didn't really know how to figure out what the right value was. And it was, you know, you would say, oh, OK, well, it's the color code. Well, that's fine. But then there were these other funny capacitors, which I had never seen before. And I have never seen, except in this kit. So we can see this sort of capacitor. This is actually a ceramic capacitor. It's, I think it's hollow. Yeah, it's hollow. And it's ceramic. Now, the thing that confused me at the time, you probably can't see it, but I'll read it out, it says 470 pj. Now, I had no idea what that meant. Of course, now I know that this is 470 pika farads. But the j kind of also threw me off, especially when in the schematics, they called it pf. And I'm like, well, I don't have a pf. I have a pj. Yeah, so I didn't really know what the hell that was. This one, for example, says 10n. And I think that's an s. So, you know, again, what's an s? I had no idea. Now I know this is 10 nanofarads, but you know. So these polyester capacitor, I think these are polyester capacitors. These were clearly marked, like this one is 0.1 microfarads. And then we have the electrolytic capacitors. And also these are clearly marked. This one's 680 microfarads. But then you got these deals. And, you know, they have a color code. But again, I couldn't really read the color code. Now I know that this is 1-0-0-0. And I'm not sure what the yellow bar means. This would be what? 1 nanofarad, I guess? Because that would be in pika farads. So I'll have to look that up. Let's see. Here's another one of these funny ones. This one is 2-7-0-0. And it kind of looks like there's a white stripe on it. So and then we have these more different capacitors. There are all sorts of, there are literally one, two, three, four, five different kinds of capacitors in this kit, but only one different kind of resistor. So that really threw me off. And I had no idea what I was doing. They included some diodes. They included some nicely color-coded transistors. Of course, summer NPN and summer PNP. We've got a white one, a green one, and a red one. And then we have some variable capacitors here. This is a dual variable capacitor for building the radio circuits. These are actually not transformers, but actually filters, because I see that there's a capacitor over here. So this is a filter. I guess this is the same filter. This one is just a winding. So this is probably just a transformer, an RF transformer. We've also got these things, coils, which go on this ferrite stick. So this would be your antenna for AM radios and things. And we've got a potentiometer here with an integral switch. We've got another transformer. I believe this is an audio transformer. Two speakers, lamps, lamp holders, lamp covers to make them red. This is a, I think this is a temperature-varying resistor, an NTC, a negative temperature coefficient resistor. So its resistance goes down as you heat it up. This is a light-sensitive resistor, or LDR, light-dependent resistor. Let's see what other components they had. OK, this is a choke. Basically, it's a large inductor. And let's see. We have some trimmer resistor. They call these trimmer resistors. But to me, they're just potentiometers. So that's one of those. Let's see. And we've got a whole bunch of wire. We've got a switch. And let's see what else we have. OK, so you might be wondering, what are all these springs? And the way that these kits were put together is that you have these plates. And you have these springs. And then you have these little clips. So you have this clip here, and a spring. And what happens is you put the clip underneath, and then you put the spring on top, just like that. And now you can push the spring down and clip a component lead in there. So for example, if the diagram called for, let's see. Oh, it was also nice, it came with all these blown up paper diagrams that you could actually place on the plates and then actually poke holes through them so that you could be sure that you were doing the right thing. Of course, that didn't help me. So you could take another one of these. And these would always get tangled into this ball. So let's just put another one here. And if the diagram called for this particular resistor to go between here and here, you would just stick this here and stick this here and there you go. So this was basically point to point wiring. So that's how you would put together these kits. Now it also came with this control panel, which you had to assemble yourself. So a speaker would go over here in this control panel. The three lights that were included would go here. The potentiometers and variable capacitors would go here. There would be something else over here. Let's see. And you could put switches over here. So one of these switches would actually go, would be mounted in here. And then the wires for that would run out to these holes where you would put the clips and springs. And the wires would come out of these holes. And then you would wire your circuit up to these connections. So the plates would fit together like this. And you would connect them using nuts and bolts. And it came with a whole bunch of nuts and bolts. I don't think this is the original container. But yeah, so all the nuts and bolts would be in here. And you also got these battery clips, well, these things. Now the batteries that they used, they used a nine volt, well, two, four and a half volt batteries to power this thing. Let me see if I can find the picture for it. Well, OK, so in the diagrams, they have it as these sort of two semicircles. But in one of them, they actually show the whole thing. Yeah, here we go. So here's a picture of the battery that they used. And you would use two of them. Of course, I never had these. And I had never seen these before. And although it does tell you here that you use nine volts. So of course, I did put together batteries that were nine volts. But again, I didn't know what I was doing, so maybe I got it wrong. Who knows? So there are two books that came with it. One thing I should mention is that originally the kits were actually smaller. And this is the EE2000, which combines all of the other kits in the series. So that's why you had two books. And they have all the experiments in it. So this is the book for basics of electronics. So for example, you can tell that it's very basic, because all you're doing here is you're taking the battery and a switch and a light and some resistors. And it's basically teaching you that two resistors in series is the sum of their resistance. Two resistors in parallel. And here we're doing current measurement. But of course, it didn't come with a voltmeter, so you couldn't measure the current. So here we're using a variable resistor. And I guess you would look at the intensity of the light to tell that, yes, you were changing the current through it. And it went through, OK, so here's another component that would do the same thing. And then it goes into the light dependent resistor. So you could see what was going on there. So basically, this taught you a lot about all the different components. And then it would start combining the components. And for example, here is a circuit where, well, I guess you're just shining a light into the light dependent resistor and doing something with it. I don't know what, because there's really no speaker here. So I don't know what you were supposed to learn about this. Let's see. So here's a circuit with a speaker. So this is a, OK, so this one, I can tell, is a Morse something or other with a loudspeaker. So I guess that's a Morse coder or a Morse keer. And let's see. I guess this is the push button. So this push button would, you know, you would tap and you would hear the sounds. Great. And again, a lot of the circuits were just sort of like build this and it works. Honestly, I don't really know what you could possibly learn from this without actually measuring voltages and currents and things like that. Here, though, we start getting into radio circuits. So this is where the more interesting thing is, because you can build a radio circuit, turn it on, and you could start tuning it and hearing radio stations. This one is a tone frequency generator. Yeah, so. And then you got this book, which was basically virtually all, well, OK, so it was basically more than the same. Basically, OK, so this is an in-out switch. I think that this is probably a flip-flop. It looks like a flip-flop, OK? So we've got two lights over here. Now, again, I still don't speak German, but hey, today we have Google Translate, so I can read all this. OK, this is interesting. So here's a circuit that does something. It does something. And the plan is completely blank. I guess at that point, you should be advanced enough to know how to put a schematic together without having to see the plans, with the exception of this enormous thing. So this is an actual full-blown radio. And then it actually gets into a little bit of digital electronics, digital technique. So it teaches you about Boolean, some of the gates, and then you actually put together a gate. This is a gate. So I guess this is an AND gate, it looks like. And later kits, I think, had integrated circuits in it, but this was way too early for that. So yeah. So that's this kit. Now what I thought I would do is actually build some of these circuits. So for example, some of the circuits that I was pointing at and wondering, what exactly does that do? It doesn't look like it does anything. I would build it and see what it does. I would probably skip some of the earlier ones, which is sort of like put the circuit together. And now you know that the transistor actually does something. Instead, maybe I'll put together, I don't know, something like this. It says Regal Baris Blitzlicht, which I can translate right now. So according to this, translated, this is 3.04. That's the circuit number. Adjustable Flashlight. It says this circuit corresponds to and then translates as device 3.03. But I think it's talking about this thing, blinking light with something or other. And it basically says, however, the light bulb flashes only briefly while the time in which it does not light much longer. So basically it goes blink, blink. This device is used as a warning light and uses little power. This is especially important when operating warning lights with batteries at construction sites on rural roads. So it says, prepare the structure of the device according to the general construction manual. Fasten the components and connecting wires according to the wiring diagram. For resistors and capacitors, you use the code table. And then a lot of this is basically just on every single circuit. It says, important, pay attention to correct polarity of the transistors and electrolytic capacitors. Screw the base plate to the control panel and make connections to the corresponding connections. Special, it says, special work, let's see. Special work, do not connect batteries. Pay attention to polarity. Final check of the construction and switching on the device. Turn the potentiometer knob to the right. The lamp flashes. In which rhythm the lamp should flash, you adjust the potentiometer. Turn right, you got a long dark phase. Turn left, short. If the lamp does not light up, switch off immediately and look for the error. So that's basically what this is. So we can actually go ahead and build that. Now, in order to build that, we can see that on the control panel, we're going to need the light. And we're going to need the potentiometer with the integrated switch. We're also going to need a 9-volt battery of some kind. So let's go ahead and put together the control panel first. And I'm not going to bother taking out the correct plan and using it. The person who owned this before apparently did put together some of these. You can see that there are holes in this plan and in a few of the others. But for the most part, the rest of the plans are intact. And I'm just, of course, going to keep them that way. Of course, today I can read a schematic, so I don't really need this. It came with this grouping and this grouping and this grouping and this grouping. It also came with a little note, I guess, showing what the old dual capacitor looked like and the new one. So that was just a little change in there. What else do they have? They have a component list, which somebody has already nicely checked off, I guess, when they first got it. But I could probably check that again. And it has one of these, two of these base plates and just a little, I'm not sure I would call this a catalog, but it does basically give you a course book, I guess. Band 1, that would be level 1 and level 2, so electronics. And I'm not sure what this is, but it looks like they're using the water analogy to explain alternating current here. This is just the construction of a transistor. Let's see what this is. I have no idea what this is. It says a, this is a hi-fi something or other. Oh, OK. Platinum real, so this is for a record player. So whatever that is, marketing, I guess. So yeah, so let's go ahead and put the components that we need into here first. So the first thing that they start talking about is how to build the control panel. So there's the control panel right there. And the very first thing that we're going to put in the control panel is the light holder. So here is a bulb, which hopefully the bulb still works. The filament looks intact, so I'm pretty sure it'll work. And let me get a voltmeter. So here I have a voltmeter. And let's just measure the resistance here. 12 and 1 half ohms, that seems pretty good. OK, so let's see. So here's one of the holders. It's white, unlike in diagram, which is black. And they're all bent like this, where one of the leads goes up and the other lead goes out, unlike in this diagram. But that's OK. It doesn't really matter. And they say to put it right over here in the middle. So that's this. And it appears that there is this little nub over here where there's a little indentation in there. So that should be able to just fit right in there. Then I can screw the light in on the top. And then I can put the red cap on. And that should just fit right around the light. It doesn't really. It really doesn't. It actually doesn't. I wonder why that is. Are the lights just too big for this? So this is how it's supposed to look. But I'm not really having a whole, ah, there we go. Well, OK. So I do end up having to squeeze it a little bit. And I don't really like that. But I just won't really press it in. So that's fun. Now to put the wires on here, there are these smaller springs which would go onto the connections. And then you would take a wire and just run it from here out to here. So first thing that I'm going to do is take one of these clips and bring it out. Does it say which terminals I should bring them out to? No. So I guess I'm just going to wing it. So there's one this spring and put this here. So these are the two terminals for the light. Now in terms of wire, there's the original spool of wire. And apparently there is some extra wire in here. I'm not going to use this because I've got my own wire. Now the wire that they have is solid core. I also have solid core. So that's good. So let's just go ahead and feed this wire in here and get the spring, place it on the terminal, squeeze the spring down, and insert the wire. OK. It's a little precarious, but it'll do. Now I'll just cut off the wire and cut it to a nice size. It's not too big. Let's strip it. And it just came out. So that's not great. Let's try that again. Yeah, one of the other things that I remember about this is that the orientation of the clip was kind of important to get the wires to go in the right place. Otherwise, you had to bend the wires and components. OK, so that's the one. Let's do the other one. I need another small spring. Hope I don't run out of springs. So that's in there like that. And this will go onto this terminal just like that. All right, so now I have the light. I'll just bring my meter in here and make sure that the connection is good. Indeed it is. And again, this is something that when I was just starting out in electronics, I didn't know that I needed a voltmeter or even what a voltmeter was for. So as I was building it, I could have checked as I was going along, but I didn't know. All right, so that's this. This is a component of a switch. So the idea is that this can sort of go up and down. And where does that go? That would actually go on a plate. So I think pretty sure it doesn't go anywhere in here. So we'll just leave this out of it. All right, what else did we need? We needed the potentiometer. So this one has a switch in it. And oh no, one of the terminals on this is broken off. Well, I guess I'm going to have to fix that with some solder. I'll be right back. OK, well, I've added another wire. So that should be that. Let's test this. So here we go in resistance mode. Let's test the outer terminals first. And we can see that this is a nothing. That's interesting. Maybe I need to turn it on. Interesting. I'm not getting any reading whatsoever. All right, well, it looks like what I'm going to have to do is open this up and see what the problem is. And if I can't solve the problem, I'll just have to get another potentiometer. Let's see, what value does it say the potentiometer should be? Let's see, Widerstand, those are resistors. Transistor, diode, diode, diode, diode, well. Let's see, here we go. Potentiometer, mit Schalter, that's a switch. Und Mutter, I'm not really sure what that is. Let's check Google Translate. But it does say it's 10K. So all right, so I want this to be translated. Potentiometer with switch and nut. OK, so I guess that's this part of it. So let's see about opening this up and figuring out what's wrong. So I've removed the nut and the washer. And I see these four tabs on the side. So I'm going to pry those open and see what's inside. All right, I've opened up the tabs carefully and slowly because I don't want to cause any metal fatigue. And let's see what's inside here. So this is the variable part of the potentiometer. And I think this plastic piece then goes up against this plastic piece with which must be the switch. So if I put this back like this and then rotate, I should be able to activate the switch, hopefully. Well, I'll figure that part out later. Part we have to concentrate on is this wiper. So interesting. OK, so setting the wiper aside, obviously, we should get resistance across these two parts over here. And let's see, again, if we are. Well, now we are. So what was wrong? Seems OK now. So I'm going on the part and we've got 10.3K. Oh, maybe a part of it is cracked, actually. Yeah, see, I'm touching it and we're getting a little bit of resistance. Oh, that's going through my fingers. That's why. So here I am near the end of the travel. So I'm going to bring it up and see that the resistance is going up. And all of a sudden, it stops. So I think what's going on is that there may be a crack in here. Oh, yeah. And actually, yeah. So yeah, the thing is actually completely cracked. So this is a piece that I'm definitely going to have to completely replace. So I'll be back when I get another potentiometer replacement that also has a switch. So while I'm waiting for that potentiometer to come in, I took a look at this potentiometer, which is supposed to be a 47K trimmer capacitor. And I did test it, and it tests out correctly. It is a linear potentiometer. Actually, the terminals are measuring 44K rather than 47K. That's plus or minus 10%. That's fine. And if I put the wiper in the middle, I do read about 22K. So this is indeed a linear trimmer. Now, one thing that I suddenly remembered is that there was actually a chart here showing how to read the markings on these capacitors. So these are the markings which are color-coded. And this one is not. And we see, let's see. So this is the color code over here. This is the value over here. And this is other markings. So you can see that the markings have a P on it, or they could have a K, or 4K7, or 4.7N, or 4N7. This all means 4,700P gopherds. Notice again that there's no J or S at the end, which confused me to no end. So I also happen to learn the German colors from this. So brown, schwarz, brown, schwarz, schwarz is, of course, brown, black, black. So rot, rot, schwarz. I'm probably terribly mispronouncing that. It would be interesting if they had those other funny looking capacitors in here. And I'm sure they do at some point. But I could just take my voltmeter, which has a capacitance mode, and just put it into capacitance mode and take one of these capacitors. Now this has a color code of. It looks like yellow violet red, which is 4,700. So this should read as 4.7 nanofarads. And it doesn't seem to be reading as anything at all. That's weird, unless maybe it's because I'm holding it. Oh, there we go. OK, yeah, it was because I was holding the leads. So this is 5.2, which is close enough. So here's the ceramic one that reads 10ns, which, of course, should be 10 nanofarads. And we're reading 8.8, which is just fine. Here are these sort of candy-like ones. This one is 0.047 microfarads. So this should also read 47 nanofarads. And it's reading 49, which is just fine. Here's a polyester capacitor. This one says 0.1 microfarads. And we're reading 100 nanofarads. So that's a good one. And then we've got the electrolytic one. So the positive end is here, and this one is 100 microfarads. And we're reading 450 microfarads. That's quite a lot. Did I get this right? Yeah, this says 100 microfarads at 10 volts. And we're reading 465. Let's try another one. This looks like the same kind. It isn't. This is 4.7 microfarads. And we're getting 15 or 16. That could mean that this isn't a great high-capacitance measure. Here's one that is, I can't even read it. The markings are not very clear. It kind of looks like 10 microfarads. So that's reading 13. That's quite a bit off. That's 30% off. Let's see. Here's one that says it's 10 also. Let's see this one. 26. Wow. Here's a big one. This one is 680 microfarads. And it's reading 710. That's not bad. And let's see. This one's got all of its markings removed. I think it's 100. So let's measure this one. Wow. That's really horrible. That's not even, that's like two nanofarads. OK, so I'm also going to have to replace these radial capacitors. I should probably just replace them all. Because again, this was from almost 40 years ago, I think. So I should just replace all of these. So while I'm getting the potentiometer, I will also get replacements for these. Just for grins, here is the light-dependent resistor. Let's take a look. That's the NTC. Where is the light? Here we go, LDR. Licht-tempfinlicher Widerstand. So it gives various locks. In dark, it says it's 10 megohms. But with 10 locks, it's 9K. So given that I'm not in complete darkness, I expect that I should be reading something around 9K at least. So let's see what we got. 23K. Let's bring this up to the light a little more. 18K. Let's turn it around. 65K, 88K, 90K. So yeah, it is light-dependent. Let me bring it up to the camera's monitor. All right, 44. It's clearly not putting out a whole lot of light. And now let's turn on my flashlight and see how it likes that. So I'm just going to blast the light there and see what we get. 20 ohms. Yeah, well, it's certainly light-dependent. So I would say that this is probably just fine. The other one is the temperature-dependent resistor. And it says the temperature-dependent resistor is 130 ohms. So I don't know if that's at room temperature, but let's take a look. It is 120 ohms right now. Let's breathe on it. Yeah, the temperature goes down when I breathe on it. So I'd say that's good. I guess we may as well check these diodes. These are all diodes. So let's put this on diode measurement and make sure those are OK. Let's see. Get this in the right way. 0.3, that's good. Let me make sure it doesn't conduct the other way because that would be bad. Whoops, 0.3. And the other way is nothing. Good. All right, let's try the other diode. 0.6, looking good. And 0.6, and that's good. All right, so we've got good diodes. And of course, now we can test the transistors. So let's see. I don't know whether this is NPN or PNP. It actually will say, let's see. The transistor for red is a BF194. It doesn't say what that is. So, well, it doesn't really matter. As long as we have two diodes either facing away from each other, coming at the base, or not. So maybe it's the other way around. I'm not getting a reading. Oh, there we go. OK, now I'm getting a reading. I guess it wasn't pressing hard enough. 0.7, 0.7, so that's a good one. See the base is red. Positive, 0.7, 0.7. So the red ones are good. Let's try the white ones. Let's go positive on the base again. Let's see if that's correct. Yep, 0.7, 0.7. Your standard silicon transistor. Let's check the other one. Good, good. And now let's check the green ones. So I think these are probably the opposite polarity. Let's just make sure. Put the positive on B, positive on base, right? Nothing, let's put the negative on base, 0.6, 0.68. That's good. And the final one is just fine. All right, the transistors work. Let me just make sure that the speakers actually have continuity. The speakers, or is it loudspeaker, 150 ohms. So not your 8-ohm speakers. Indeed, 150 ohms or 140. So that's good. And the other one is the same. Should I check this transformer out? I mean, I don't know what the windings are supposed to be like. So I should probably just leave it alone. I mean, I don't really know. I can put the leads across some of them. And yeah, I don't really know what I'm doing. I mean, it kind of sort of seems like something's going on. So I don't know. Same thing with these coils. Again, not really sure whether it's continuous winding or not. I could just try. There's continuity. There is no continuity. No continuity. Some continuity. I guess these are two coils. I could check the inductor here. Make sure that there is actually continuity. There is. Good. OK, I think that pretty much covers everything. These, I'm pretty sure, are fine. So I'm not even going to bother with checking them. I suppose I could check these variable capacitors, but I'm not sure what they're supposed to be reading. Does it say here, polyester electrolytic ceramic? Here we go. This is the variable condenser, one of them. So this is the single one, 5, 280 picofarads. I'm not sure I'll be able to measure that. Let's see. It's giving me 400 picofarads. Of course, I'm not in all doubt or anything. And it does seem to change when I turn it. So I guess that'll be OK. And this is the dual one. So this is the two-fax dré condensator, 180 picofarads, same thing. So again, I'm not sure which terminal is which. Yeah, I don't know. I guess it'll be OK. So all right. So I think everything is OK, except for the potentiometer and the electrolytics. So that's what I'm going to replace. Well, it's been a few days. And I've gotten my components back from Digi-Key. So I've got all the electrolytic capacitors that I need. I've also got some battery compartments, battery holders for D cells and C cells, which go up to 9 volts. So that can power this thing because it takes 9 volts. Unfortunately, it looks like the potentiometer that I got is the wrong size. I mean, clearly it's smaller. It does have a switch. It is 10K. It is logarithmic. So really, the only thing that I kind of care about is, will it actually fit into here? And it does sort of, let's see. So I think the idea is that I would just be able to connect that up like this. And then, yeah, that works. It's got a button. I mean, it's got a switch. So I think that works. The only question is, there's a knob that's supposed to go on it. And it's probably going to be a little too big. It does have a place for a screw, but I don't know if this is actually going to work. But you know, I'll live with it. I did find out that where you put the connections for each of these components is actually in the book. So it's basically right there. The numbers over here tell you where the things go. So we need to put in, let's see, which one were we doing? 3.04 or something? 3.04. So really, so I need to install that potentiometer. And the wires will go to 14 through 18 with the switch on 17 and 18. And that's all. So the other thing is that this doesn't contain any holes in the leads. So I can't really put a spring on it. I really do have to solder up some things. So now the other thing is that there's this scale that's printed. That's fine because you can just adjust the knob when you place it onto the shaft to 0.0. Of course, the question is, will it go all the way to 10? And that's a question that I don't really know. I like to think that these are kind of standard, so they all go however many degrees this is. But I guess we'll see. So let me solder up those wires and hook them up to 17. Guess it's 17 through 21, did I say? No, 14 through 18. So 14, 14 through 18. There's supposed to be a push button that goes here, but that's not being used. So I won't put that in. All right, so in order to install the knob, see are there instructions on how to install the knob? Doesn't look like it. Yes, actually there is. OK, so there's this square nut thing and a set screw that goes into this knob thing. So I got this whole bunch of hardware. Here is a square nut, the set screw, and that goes in here. OK, I guess it just sits in there. I'm not convinced that this is actually going to work because the shaft is too small. But I can try it. Nope, there's no way that that's going to work. OK, well, that's OK. I have a 3D printer, so maybe I can 3D print something up, design something that's as large as this, but inside it's smaller so that I can attach it. I can do that, but not right now. Right now I want to get the rest of the circuit working. So let's see. Those are all the controls that I need to put into the control panel. So now the next thing to do is attach these things, these plates. First, you would connect the two together. So, huh, OK, I don't remember them actually snapping into place. Well, OK, there are holes through here and here where you put screws, which should be included. So yeah, there are these screws. And they would go through the holes. And then there should be some nuts. The nuts weren't included. OK, that's fine. So we just won't attach these yet. So we can just push this together and pretend that it's secured. OK, so the next thing we need to do is build the circuit. So we'll go according to this. So I guess we just see if the disappointments of my childhood get replayed. Nothing's happening. Not a damn thing is happening. OK, one possibility is that the wires from the lamp in the back got disconnected. So let me double check that. No, it looks OK. Looks fine. All right, let's do some basic debugging. So the first thing that I'm going to do is make sure that the switch is actually doing what I think it does. So I'm going to connect these here, turn it off, turn it on. OK, that's what's supposed to happen. Let's see. Next I will take a look at the resistance across the light, which of course is going to be different because it's in circuit. But I'm getting 12.6 ohms in one direction, 12.6 ohms in the other direction. So I think that's fine. Let's just see, making sure that all the connections seem OK. This one seems a little loose. Let me maybe tighten that up. All right, let's try one more time. And let's just make sure that we are getting power. So volts ground here and power here. Oh, I see 0.4 volts. That's obviously not correct. Let's undo this and see if the problem is with the battery terminal. OK, so I'm getting 7.6 volts. That seems pretty anemic. And I'm wondering if it's just because the circuit is drawing a whole lot of power. So what I can do, make this up, make sure this is turned off, and put this into current mode and go to milliamps. So right now it's drawing, oh, it's on AC DC. It's drawing nothing. So now when I turn it on, it's drawing practically nothing. Let's go back to volts and double check. I have 7.7 volts, 0.3 volts. That doesn't make any sense. Oh, wait, it's on. Now if it's off, 7.1, 7.2. OK, so clearly this circuit is effectively drawing so much from the batteries that the batteries just can't keep up. So let's take a look and see what is going on. So the first thing that I would probably check is to make sure that none of these resistors are actually shorted. So let's see, 47k. I'm just going to measure them in circuit to see what's what. OK, so this is actually measuring, well, it's 120 and it's going down because of the capacitors in the circuit. But it certainly doesn't seem like a short. This is measuring 3.3, which I guess makes sense because it's in kind of in parallel with this. And then this is 2.2, which is correct. This is 3.2k, which is approximately correct. This is supposed to be 220 and it pretty much is. So I don't think that's the problem and I don't think it's any of these capacitors. They are pointing the right way. See, I got this transistor BEC, that's correct. This transistor BEC, that's correct. And I didn't check this resistor, which is 1k, which is correct. All right, so what could possibly be going wrong? Well, let's take a look at the schematic and take a look at the battery and see what could possibly be driving it. Well, OK, so one possibility is that if this transistor is on very hard, then this battery is just going to go right through this lamp and down to ground. So maybe what I could do, first of all, is maybe run the lamp off the batteries, right? Because it says it's supposed to be a six-volt lamp. So let's disconnect one of the connections from the lamp and make sure that the lamp is actually working. So the lamp is not even running. That's interesting. So let's see. Let me take a look at one of these lamps. See if this one lights up. That one's not lighting up. And that one's not lighting up either. Are all these lamps just duds? I think so. Well, I think we've solved one of the mysteries. But the other mystery is that I measure the resistance on these bulbs and they're correct. So why aren't they lighting up? Let's double check that. It just doesn't make a whole lot of sense. All right, here's a lamp holder. So let's just screw this in. Let's check the resistance. OK, see the resistance is 13 ohms or so. And that to me says that the filament is OK. See, that just doesn't make any sense. All right, a last thing to check is the voltage as it's powering the lamp. So zero. I'm getting zero. These batteries are probably dead. That's the only thing that I can think of that the batteries are completely dead. So in fact, I measure them now. Yep, they are pretty much flat. OK, well, that probably explains things. Unfortunately, I'm going to have to get more batteries. What I can do is just get a 9-volt battery. Now these 9-volt batteries aren't really meant to drive high currents. Let's measure the battery. Nice 9-volts. Let's see what happens when I, yep, OK. So, OK, unfortunately, I don't have a connector for this. So what I'm going to do is I'm just going to turn this on. And I'm going to make it so that I can actually just put the battery terminals onto like here, which is the negative side, this side. So I just want to do this. So that means that I want one spring clip here. I want a wire that goes from here up to here. Now the weird thing is that I bought these batteries, well, a while ago, and they've just been sitting in the drawer. And why wouldn't they last more than a few years? I don't know. OK, so let's see if the circuit will actually run on a 9-volt battery. Ah, there we go. OK, well, that's how it's supposed to work. It says it's like an emergency flasher or a roadside flasher. And you can change the timing. They could go slow. This is as slow as it's going to go. All right, well, hooray, I've got a circuit that works. Now the interesting thing is that when I was a kid, I would have basically stopped the moment the circuit didn't work, and I wouldn't know how to diagnose this problem. Today, being an adult, and if I was a kid and I had YouTube, I could probably figure this out. But I didn't at that point, so. OK, circuit description for the advanced. This circuit is also a multivibrator. However, unlike the previous circuits, the incandescent bulb flashes only briefly while its dark time is considerably longer. Once again, the RC elements play a decisive role in the base circuits of the transistors. Since the transistor T2, it's this one, conducts only briefly the light bulb flashes only briefly. The base voltage of T2 is determined by the very high resistance R, R7, that's this one. It's different with T1, which is only briefly locked and in which small resistors determine the base voltage. With the potentiometer R3, the dark time can be set, but the flash duration cannot be changed. So I guess if you understand multivibrators, which apparently the previous circuits were about. So there's one, there's another one, this one. So yeah, so anyway, there you go. One of the circuits that would have totally stymied me when I was a kid, and it works now. There you go, eight-year-old me. You were wrong all this time, and it does work.