 Ding dong The time at the sound of the cursing engineer will be 11 30 a.m. Pacific time God damn it greetings everyone I'm on okay, so This is just going to be video of me soldering up the ALU For the risk 5 processor that I'm building now I have a tester and a backplane and the tester and backplane are currently being tested by a friend So I won't actually be able to test the ALU until that is actually complete But at least I can get a start on soldering this up And that's probably where the thumbs down came from because I said beforehand that I was going to pronounce solder Like folder and not like solder So let's see so the ALU Let me change the camera around so that I can draw some diagrams Let's see I'm gonna make everybody a little dizzy, but that's okay. Let's zoom in on a piece of paper focus, okay, so This is the way that the ALU works now on the backplane I have three buses a destination bus and a source one bus and A source two bus and all of these are 32-bit buses 32-bit buses. So, you know if you had an ALU, which is typically this symbol here You know what you could do is you could connect source one up to one of the inputs and Source two up to the other input and then There's some sort of a function over here that you tell the ALU what to do and then the output goes to the destination and Of course source one can come from a register source two can come from a register, you know Or maybe it's an immediate value or whatever and the destination would typically go to a register At least in risk five The other interesting thing about risk five is that the ALU has no flags Normally on Sysc processors and even on some risk processors There are flags coming out of the ALU things like you know zero If the result is zero see for if there was a carry out that sort of thing Risk five does not have any such thing so Functions are things like add subtract xor or and And there's also set if less than so that's one of the instructions So how does the ALU actually work? Well, we can start with Addition that's really the hardest thing to do in this case Oh By the way, there is no shift that I'm putting in the ALU because shift is a fundamentally different operation from all of these So that's actually going on a second card Okay Soldering we are soldering Soon, okay so With an adder, you know, there's the typical full adder full adder with a carry-in and You get you know one bit. I'll call it a And another bit. I'll call it B and the output. I'll call it X and you get a carry out and A ripple adder Basically just connects a whole bunch of them together in a line like this Okay, so if this is you know a zero a one This is going to be a 31 in my 32-bit bus Okay, so we have 32 outputs. We've got We've got a carry out which of course we don't do anything with because risk five doesn't have a carry out So the idea here is that the full adder computes the sum of the carry in the a and the b and Outputs a sum bit and a carry out bit and that feeds to the next full adder and so on so the problem is that if this full adder incurs a delay of Delta then you will only get Delta from the input of a zero to the output of X zero and also carry out, right? So so this is basically a propagation delay of Delta so this would be two Delta three Delta and So on all the way down to 32 Delta. So the longer your The longer the the more number of bits you have the longer your delay is in fact your delay is going to be order n Based on the number of bits now. There is a carry look ahead way of doing things. Oh, yeah, you can improve this You can improve this by having a full adder that actually takes multiple bits at a time So, you know, this could be a zero to a three and this could be be zero to be three This would be your carry in this would be your carry out your sum would be x zero to three, you know and You know the advantage of doing this is that this is Probably about the same sort of delay because it probably has the same number of levels of logic inside Maybe a little more But at least you won't have 32 full adders Let's call this a quad full adder Instead you're going to have just eight of these so you will incur a delay of eight Delta now Again, the delay is order n Sure, and as you know, there's a factor in here But, you know in in in algorithms, you don't count the constant factor It's still order n so that you know that as you increase the number of bits the delay Linearly is linearly associated with that. So then there is the carry look ahead method and With the carry look ahead what you do is let's pose again. You have our quad full adder and you have a carry in and You have four bits coming in four bits coming in and What you do is you have a Sum and Also two bits called propagate and generate I've gone over this in previous videos But I may as well just go over it again because why not? And the idea is that if you have a whole bunch of these full adders and They're all outputting propagate and generate and what propagate and generate mean is if Propagate is high that means that the Inputs are such that if the carry in whatever the carry in is that's what gets propagated to the carry out And you can calculate that fairly easily the generate bit is set when There is a carry out regardless of whether there's a carry in or not So for example Let's suppose you're adding you know these four bits and they're 15 plus 15 Well, the answer is 30. You're absolutely going to generate a carry bit So you can you can compute what P and G are just based on the two inputs and that incurs some propagation delay What you do is you feed all of the propagation and generation bits into a carry lookahead unit What the carry lookahead unit does is now look these are only two bits two bits two bits two bits It computes the logic to generate The carry ins to all of these right because all you need to know For the carry in of the next unit is the carry in of the previous unit and whether it's going to propagate that carry in Or whether it's going to generate a carry out So this will incur just a delay of Delta Right because this isn't a ripple this this actually just takes all of these bits and computes all of the output bits all at once Once it does that so we have Delta here we have Delta here and then of course we have these outputs and These outputs are going to incur another delay right because once you put the final carry in into a full adder unit You have another propagation delay until you get the final output So in this particular case it doesn't matter how many of these you have as long as your carry lookahead unit is big enough You only incur a delay of three Delta and that is order one In other words, it does not matter how many bits you have now in practice These carry lookahead units will end up being limited By the number of bits you put in because the more bits you put in the more complex the logic gets So you could actually end up with multiple carry lookahead units and Interestingly the equations of a carry lookahead unit allow you to take multiple carry lookahead units and feed them into a carry lookahead unit So if you end up in that situation then basically you get another Delta For this carry lookahead unit and then another Delta for this carry lookahead unit which generates the bit So I think it's what one two three four Delta and you still end up with order one The logic gets a little more complicated and of course the logic is lots more complicated than just a ripple adder but at least Your output is an order and it's order one. Does that make sense? I hope that makes sense And you can look at You can look at online Especially on wikipedia about carry lookahead units and it talks about the equations So it's a really useful thing to to know about All right Let's see. What else should we do? Okay, so that is an adder now a subtractor Basically what a subtractor does is it modifies the second argument To basically invert it And instead of a carry in you have a borrow in Same concept so you can use basically the same circuitry It's just that you have to have a little bit of extra circuitry on the other input And basically that tells you whether you're doing a subtraction or an addition now once you have subtraction you can also do comparisons right because If you want to determine whether Whether a is less than b Then all you have to do is compute a minus b and if that's less than zero then a is less than b I think there's also another bit for signed and unsigned comparisons because of course if you have say let's suppose you have a 16-bit input so your inputs you know could be zero zero to Ff well in signed arithmetic You have a range from I think it's 80 to zero zero To seven F. So this is minus 128. This is zero and this is 127 so that would be it in signed and of course in unsigned you can represent numbers from zero to 255 So if you do a comparison between two numbers if you want to compare is zero less than ff in unsigned Then the answer is yes, but if zero is less than ff, which is minus one in signed Well, then the answer is no so there's an additional bit in here to determine whether you're doing a signed or an unsigned Subtract or a signed or unsigned Comparison All right, so that's the circuitry there would also be other inputs to to hear Saying whether you're just doing a logical X or or a logical or or a logical and so basically bypasses all this circuitry Or actually just passes it through With the logic and the carry lookahead unit is basically disabled. It wouldn't do anything All right Okay, so you can Write the logic equations for this But there is another method of doing it And that's called cadet Can't add doesn't even try And what this does is instead of a full adder So here's a full adder here's the carry in Here are say four bits input and you have Two bits for propagate and generate and you have four bits for the sum so that's nine bits in and six bits out So that is a five twelve by six Ram or rum actually So instead of actually putting logic here if your memory is fast enough you could just replace this with memory And then your propagation delays will be even lower and this is This is not really the case for integrated circuits By which I mean integrating this Into a single integrated circuit what I mean is a discrete solution, which is you know what they did in the 70s and the 80s When they didn't really have microprocessors or readily available ones and that's what I'm doing because of course my circuit is a Is not on and have PGA? That's how it works So you can use memory over here That's for the full adder the same thing for the carry look ahead unit the carry look ahead unit takes in What is it eight say let's suppose it's eight? Propagate and generate bits plus it also has to have the carry in and Then it generates say for carry outs Yeah, and that's it. So again, this is a five twelve by four rum So that is what I'm using. I'm using the cadet model So the way it basically works is Here are my buses and then I have buffers here and then I have one layer of memory Which acts as the propagate and generate Generator RAM. So this is or wrong. So this is memory And this is actually divided into like groups of four bits So the result goes to a carry look ahead unit, which is also memory however many bits that is Which generates all the carry outs? So these are all the carry outs. There's also a carry in which is not given to it It's actually generated By the function that is occurring because when you're doing an ad There is no carry in ad or you know like the equivalent of an ad with carry instruction in risk five So carry in would always be zero for an ad It's also the borrow in for a subtraction. So that would always be set to one for subtraction and For comparisons. So these are the propagate and generate bits. These are the A and B inputs This is the carry out that goes to The adder Along with all of these things. So these go over here and then there's the output So this is another memory now you might ask well, why didn't I just and this was actually a The a bug in the previous design is that why didn't I just combine the adder with the propagate and generate Memory and just feed back the input the outputs from the CLU back to the memory Well, the problem is that when you do that, this is the address and this is the data And there's always going to be you know some period of time where the data is not stable when the address changes So the problem is that if the address Is say something then the data comes out and it's not stable for a certain period of time That means that the data here is not stable for a certain period of time And when it gets fed back that means that the address here is not stable for a certain amount of time Which means that this the instability just sort of feeds back on itself Eventually it might settle down into the correct state, but the problem is that we don't you know, that's not necessarily true So that's why I had to go with a layered structure like this So three layers of memory then we get the output the output goes through a buffer and gets put back on the bus the destination bus So the reason that I have these buffers here instead of going directly to the memory is that I have a backplane Which means that every card adds Capacitance to each line. So of course by putting a low input capacitance buffer in here I'm able to reduce the overall capacitance which allows the bus to be driven properly The disadvantage of that is of course that each buffer generates Leads to a propagation delay. So oh well So there's a propagation delay from here, and then there's one here one here one here and one here So overall it's going to be you know five propagation delays And I think these memories are like 10 nanoseconds. So 10 nanoseconds 10 nanoseconds 10 nanoseconds, and I think the typical Propagation delay of the buffer is like seven nanoseconds or something like that So, you know, we're talking 44 nanoseconds, which you know isn't great when you consider It's about 50 nanoseconds, which means that the most you could ever do in adding would be say 20 megahertz It really sounds small. It really sounds low 20 megahertz Compared to you know today's gigahertz chips But the only reason that they were able to get to gigahertz range is that it's all integrated on one chip And all the features are really really tiny and small So your propagation delays are down in the picosecond range instead of the nanosecond range That's just the way it is also these chips have to have buffers internally between The input and the output For signal conditioning because obviously when you're inside a chip You know, and you're just and and you know exactly the You know exactly the the logic that you're feeding inside the chip Well, you don't need you know a generic output driver So they dispense with all the intermediate output drivers and that's That's what you know really contributes to the to the propagation delay here There are other ways to get faster Propagation delays things like ECL I squared L All sorts of different types of logic. They all take a lot more power once you get into the higher speeds I'm just using CMOS So anyway That's the rough calculation Let's get soldering First let's check the chat see if there are any questions Mmm Let's see is there a rhyme or reason To when pins are zero indexed and one indexed ie a zero versus s one Generally I don't know I mean I always number them starting from zero Because that's just the way binary works if you've got a large bus The first signal is going to be named zero. I Have actually seen chips where they don't do that. I'm looking at you TMS 9000 They actually start from one which really made me angry in the face So let's see yeah in terms of like s1 and s2, okay, so for example, I think on the 74 138 which is a three to eight decoder Three line to eight line decoder. They have two Enables called g1 and g2 In that case, you know the the the two enables don't form a digit They're just two enables So, you know you could call them g0 or g1 or you can call them g1 or g2 That doesn't actually matter where it does matter is when you're having you know a bus of like data lines and address lines And it's important to have them ordered correctly And they represent binary numbers. So you you have to start with zero That's my explanation. I don't know if it's correct, but sure sounds correct. All right. Let me move the camera Let's see black screen You know why we have a black screen Let's tell you why we have a black screen It's because the infrared receiver on the input switcher of my video Actually interpreted the moving of the paper across my ceiling light as a signal So you can tell that that thing was not engineered very well Okay So anyway, here is the circuit. I will be soldering together now. I have the fabrication list Okay fabrication list. This is the fabrication diagram that comes out of key cad So it tells me where all the chips go and what their orientations are. So I think that's like really important To see like the little diagonal lines which tell you where pin one is or where the dot on the chip should go That's really important because often often When you look at a board like this You will see let's see if I can get something to point with Actually, why don't I just put this under the microscope? Yeah, so you will see Either a line for pin one or a dot for pin one I added these dots myself because I grew up with dots not these fancy schmancy lines on footprints But anyway, the dot tells you where pin one goes. So But the problem is that that dot can rub off it might not be printed by the PCB manufacturer. Well So it's always good to have a fabrication diagram to tell you What each chip is right because there's typically not really a great amount of room To tell you what that chip is. There is a designator, you know you 38. That's what this thing is But then, you know, you would have to look at a list of what you 38 corresponds to and instead I've got this You know a nice diagram Which tells you? Let's see, where is he 38 suppose am I holding this right? I think I am holding this right There's you 38 right here There you 38 So and you can see that the diagonal line Tells you where pin one is supposed to go and it also tells you what chip It's supposed to be in this case of 541. No, I did an underscore a Because I actually have different Not not exactly different pinouts, but Different designations for the eight inputs in the eight outputs So on one I have the eight inputs going from zero to seven on and on the other I have the eight inputs going from seven to zero Sometimes it's more convenient to do it one way so that you're not crossing lines Sometimes it's convenient to do it the other way. So I actually have two different pinouts kind of So, you know the underscore a designator doesn't actually mean anything once you're putting the chips down They're both 541s. So Anyway, let's see. So Let me Pull out the chat window. Let's see pop out chat That way I can see the chat All right well a whole lot of a Lot of messages rolled in It needs a clock and Rob has no clock signal in his design that is correct This is at least this section is Unclocked it's basically just straight logic from input to output the clocks come in When I decode an instruction When I clock the result into a register. So there are clocks in the design just not on this board Let's see The camera is focusing on faces. Yeah, I know I I just can't be bothered to remove that feature or to find out how to turn turn off that feature I've got more important things to do Okay, so Let's see. What have we got? Well, let's get to soldering. So I've got oh Yeah, okay. Here's something else Before I get to that. Let me switch the camera. This is something I discovered recently Okay, so if you look online And I don't have the setup to actually show you the website, but if you look online for HACCO solder solder fume extractors You will find some sort of a $70 or $80 item Well, I looked at it and it's just one of these fans Inside a nice case, right? I picked this up surplus for like five bucks. It runs off of 12 volts Right now the other thing that the HACCO fume extractor has is a filter Well, I picked up these these cheap activated carbon filters for like nothing and They happen to be just the right size for for my fan and check this out So I'm gonna put this over here where you can see it and then I'm gonna plug it in and Make sure that the That the air flow is going the correct way. Yes There That's my filter It's fairly quiet. It's probably about as quiet as the HACCO units And you know, you don't actually have to take it apart to change the filter. You just pull the filter off Okay, so that was fun, so let's see so I will be using For now this tip this tip it's just you know a conical tip. It's it's Quite small. I'll be using that for the passive components and then for the chips themselves I will be using this Which you've seen on previous soldering videos There you can see that there's a little well inside there that holds solder. So this is useful for drag soldering I also have this other one which I've had pretty good success with it's basically a knife edge and you can use that for for like QFNs because the Little tip here of the kind of chisel gets gets right in between the component in the printed circuit board So that's what I would be using so I'm gonna start with some of the passives I'll just turn on my iron to 330 Celsius Now I'm using a HACCO iron It's an FX 951 and I'm also using these shavings to clean the tip. I don't like to use a wet sponge so Yeah, surplus is awesome, isn't it? You can find all sorts of things and all you have to do you know is be a little creative, you know, just put stuff together until you Become inspired to you know actually build something Yeah, exactly everything is fine as long as the asynchronous logic is not taking longer than a clock cycle So of course you you adjust your clock so that your logic has enough time to sell. That's that's really all there is to it And you know really that's no different from anything that you call synchronous I mean you're always going to have a clock edge and then some logic and then another clock edge So of course, you know, you can't clock your your logic so fast that The signals can't propagate. All right Yeah, okay, I've got all of my parts here Here are all of my parts. So I've got some resistors resistors are used the resistors are used on Signals that need to have a defined value while the system is powering up So basically this sort of turns off all of the buffers so that you don't have multiple buffers feeding the same signal that sort of thing Got my capacitors here my reservoir charge reservoir capacitors charge reservoir capacitors are used on Every chip or every other chip or you know, I've seen on especially large boards like this one This is a board with about 600 chips. It's a floating point of array from Vintage computer this is all TTL It's not even CMOS, but yeah, so it's all TTL and There are capacitors So if you see the capacitors there, you'll see that, you know, there's roughly one every two chips So, you know, they didn't bother to put a capacitor per chip And I did which is probably honestly overkill But I don't really have a rule for you know, when I can skip capacitors, so I just put them all on Let's see. I've got an inverter The binary counter. Okay, that's important because remember that I'm using the cadet model which requires rams or rams rams are actually faster and There's a boot phase where I do have rams sitting on the board So there's a boot phase which has to load the rams into the rams So for that I need the counters Let's see. There's an OR gate in here This is This is basically most of the chips on the board. It's a 74-541 a non-inverting buffer eight bits Okay, I've got these 256k s-rams those are the memories and then I've got two types of e-squared prongs One is a 64k and one is a 256k because I found that One of them actually didn't need as much data as the other so I just used the smaller rams There are also Here These are the sockets for the rams. Unfortunately, I don't have the sockets I was going to go to the surplus store and see if I could find the sockets, but I didn't get around to it So oh well. I'll have to leave that until later and also Sprinkled throughout I think I just have like three of these electrolytic capacitors just to provide a larger reservoir local to Local to the board so what I'm going to do is start with some of the passives Maybe just in like one area And then I will put the chips down and typically when you solder a board up You want to start with the lowest laying components and then gradually work your way upwards So that you can you know, so that there's room to solder things in All right, so Actually, let me put down the resistors first So that I can get those out of the way because I know there's only like three of them or four of them So and usually what you can do with your fabrication diagram is you can actually color code them with little markers So that it's easier to see where it is instead of you know, searching around to find, you know The two resistors in your huge board. So let me go ahead and Let's see Let me just check the chat see if there's anything in here Yeah, the 74 f 181 can supposedly go over a hundred megahertz that's actually pretty good and That's an 8-bit ALU isn't it Interesting Well, the problem is that then I still need to carry look ahead, you know, otherwise I'm just rippling things and you know You sort of ruin your whole advantage right there You know and considering that my full adder is 10 nanoseconds It could also theoretically go up to a hundred megahertz It's just that it's not very useful unless you connect it up to something else. So Let's see Okay Yeah, that's right cadet was was like an IBM thing. So, okay Let's get to the board. Okay, so here is a nice section That I can do I said that I was going to do the resistors first So let's go ahead and find some resistors. I think we're all down Unless I put them on the back of the board I put one on the back of the board. Oh Here's one Right there. So I'll do those So, let's go ahead and the iron is fired up. I Will go and Take my small solder and I also have some flux. I am going to be using kester flux I have been using MG flux and I would just like to try kester Just to see how it goes the MG flux Gets pretty sticky, which I mean it's flux it. I guess it's supposed to be sticky I just was kind of hoping for something a little more liquidy So let's try it. I don't use no clean the flux Because I found that I don't know I just don't like it very much So I think the tip on this is dry because this is a totally new pen. So let's just Push the tip until until we get some Flux coming up. See it's beginning to Flux okay, cool Cool cool cool cool cool. All right, so what I'll do is Just put a little solder and then Let's see the best way to do this is like this All right Resistors here. I hope those are the right ones I actually didn't order any of the 10k is when I when I made my Order for all the parts because I figured oh, I have 10k resistors lying around somewhere And I found these and they're 0603s, which is the right size because I only use 0603s So Yeah, they're the right size You never know You know what? razor blades razor blades are One of the most useful tools you can have in your toolbox because then you can do awesome things Like that No, I can get out the resistors. Okay, so I'll take a resistor and promptly lose it. We're sure to go That's not a great start. There it is Unfortunately, my tweezers are a little sticky. Oh, I know what I'm what I forgot I forgot to get some isopropyl alcohol one moment. Yeah, always a good idea to Give your board a good rub down with isopropyl alcohol before you start soldering up Soldering it just to get any oils off of it Which I forgot to do but will do I promise Also, I'm going to clean the tweezers which are probably covered in Okay now Where my resistors go, I don't know where it went All right. Well resistors are cheap. So I'll just get another one. So what I can do is Zoom in on this a little bit. That's nice. Okay Oh It was in the footprint for the wrong. I moved it. Yeah, where'd it go? I I don't know. I was rubbing the board gently and it should have just fallen on the table, but nope so What I do with passives is I just sort of slide them on Just like that done Well, except for the other side You know the loss of that resistor really annoys me But you know, I just have to accept that it's gone and that they're really a fraction of a penny You'll notice That this resistor says zero one C Doesn't say anything about it being 10k so You just have to sort of you know, I guess you could Google it and zero one C is probably some manufacturer code Or maybe it's C ones. No, I'm pretty sure it's zero one C But you know at least the manufacturer marked it If if these are capacitors no markings no markings you lose All right, so now that I've done the two resistors I will go ahead and Rub down the area that I'm going to be working on with some isopropyl alcohol So let's see. I probably want to work on this area here from C 17 and U 17 all the way up so I'm just going to give that a little The whole bath the oils are gone and I'm using a clean q-tip or Cotton bud or cotton wool bud But yeah, because I don't want to use the one that I would use to clean off flux because that's all flux so So for the passives, of course, I will do exactly the same thing just flux capacitor for this guy Probably on the other side Flux and I may as well just do these as well So the dab of solder on there now The coating that I got for these pads is hazel Hot air solder leveling hot air solder leveling So basically there is a little bit of solder on this already So I can sort of melt it a little bit, but there's not a whole lot of it So, you know, I I just put a little bit more on because I'm a little more on Hey I'll just grab some capacitors Just dump them out grab one great Fantastic. Thanks for showing up late to the party All right, I'm gonna put this one aside on something white so that I'm not gonna lose it wowsers, okay That capacitor so you can see that the capacitor has no markings So if you wanted to reverse engineer a board You could try to measure it in circuit, but usually what you want to do is is just De-solder it out of circuit That's not a great angle. Is it? I think I should turn the board around Unfortunately, my hands are slightly shaky Because I just had some coffee so tip for engineers When you're about to do some soldering Don't caffeinate yourself before him See how wobbly this capacitor is. It's kind of wobbly I guess they're not really quite flat happy Turkey day is that today? I thought it was tomorrow tomorrow being Thursday Today is Wednesday, I don't know I don't celebrate Thanksgiving because I have no friends to go to and my family doesn't live in the area, so yay for Being an introvert Instead I get to spend my time with with all of you Not that that's a bad thing because it isn't This is a mistake. So I first Okay There just wasn't enough solder on that one and C 28 Are those all the ones that I wanted to do? One two three four five six seven sure looks like it All right Solder up the other side and the reason this is taking oops The reason you can see that it takes a long time to melt is that first of all There is no solder to form a nice heat bridge and Second of all, this is probably connected to the ground plane. So That's why it took so long to melt That's why typically what I like to do is apply the solder to the iron first where it will melt immediately then The solder drips onto the pad where it forms a nice a nice Way for the heat to get to the pad quickly. So all right Let's do these four chips We'll start with you 17 and I'll orient this So that the dot is like that What's this? Let's just do the one now all of these chips. I know for a fact are buffers There are only a few geologic chips and The Rams are pretty distinctive. They're just these, you know Sort of longer chips long chip is long There you go. I have how many of these are in here? 200 That's probably way more than enough Let us get a chip out of the bag. Let me use the razor blade because razor blades are awesome Just don't play with your razor blades Absently while you're on the phone. I Learn that lesson the hard one chip Oriented the right way So again, what I usually do is Put it down. Oh, I need to change change tips Turn the Thing off So I just use a piece of cardboard to to pull the tip out Because I'm impatient and I don't want to wait for it to cool down Let me get my tip holder ready So that makes it really quick to change tips All right Turn the thing on again All right, so since I'm going to be dragging down a line I want to orient it this way so What I do is now so I have fluxed the The pads so what I'm also going to do is I'm going to flux the pins as well So that now the solder can flow up to the pins and down to the pads as well And now what I do is I simply load up the reservoir With some solder it's like I already had some on there already Hold the chip in place Place it very carefully make sure that all the pins are lined up with all the pads So what I'll do is I'll just sort of And then very gently so that I don't move the chip around pretty neat huh done I think that may be a soft solder bridge, but I have to do just touch it To get the bridge away that's all there is to it See the idea is that there's kind of a bead of salt of solder Formed by this well so that as you drag the solder across the pins The flux will allow the solder or the fluxed metal will actually draw the solder onto the metal and not onto anything else You may get bridges, but those bridges can be easily removed so the other side flux reservoir So you can sort of see that the solder Kind of forms this little bead You do have to get the right angle on this and it takes a little bit of practice And if you don't do it for a while you sort of Lose that physical knowledge All right, there we go done That was pretty easy. So um now just to Now I can inspect it, you know by sort of zooming in And looking at it and seeing that you know for the most part it's pretty good But what I'll do Yeah, it is it is kind of like a fountain pen I love fountain pens I'm going to take my dirty q-tip Just clean it up add it and get an A That's a purple alcohol So I did order from ebay some kim wipes And a nice little alcohol dispenser Nice Very nice except for this part too much flux there All right, I know you can more clearly see the joints They're nice and shiny For the most part and that's pretty good Now normally what I would do if I had Good access to these signals I would actually test the continuity by touching on top of the pen But I don't think that I'm going to do that I'm pretty sure that this is all pretty good And if it isn't well, I'll catch that during testing Then I can probe because there's just way too many signals on those Anyway Let's do another one Yeah, I do I do like this flux. It's uh, it's certainly more liquid Then again, I've had that other flux pen for years. So, you know, maybe that has something to do with it This is a new flux pen that I just got All right, let's orient this first of all oriented The right way up and second of all oriented according to the dot Just the pins Some solder get the chip exactly where I want it Usually taken care of the other side um, so these chips are Don't have as fine pins as some of the chips that I use and it's really careful You have to be really careful when you use the flux pen not to like, you know, drag it Roughly typically what I do is I just sort of dot the fine pins like that Because they the fine pins can bend really easily and then you're not going to be very happy. So Okay, let's do the next one Yeah, um the alcohol Yeah, it was kind of fun when the alcohol revealed the lettering on the chip I've seen Dave from EEV blog just sort of put some saliva on his finger and do that but The interesting thing is that sometimes when you get boards from china and they want to sort of hide The number from you they sort of scrape off the top Sometimes they don't do so good a job So you can actually take some saliva or some alcohol and put it on top of the chip and then reveal the numbers So let me switch to the second camera. I just had an idea So the problem with using this this flux pen is that Every time that I want to first of all, you should put the cap on it Just like you should put the cap on all markers so that it doesn't dry out Second of all, uh, so when I put it down, I put the cap on when I take it I have to remove the cap so I have to do it, you know, one handed like this which is kind of You know inconvenient Because what I you know, what I do is I just sort of take it and then drop the cap and then I have to pick up the cap with Two hands. Well, you know, why don't We just like make a thing that sort of holds the pen from the cap like that and that way I can pull it And just put it down one handed That would be a neat 3d printing or you know, actually just some hot glue would work, you know, just Take a piece of metal Glue this thing to it and then you know, you're done The only thing with hot glue is that you have to be careful not to get any alcohol on it because alcohol Will actually disrupt the bonds on hot glued stuff and the hot glue will just come right off Tip in case you're ever trying to clean up hot glue from your kitchen counter So let's see this chip when you get the right angle. It's really satisfying pretty cool Next one so I'll do this next one and then I'll do this some this, uh ram chip Because I really do want to get to the ram chip Because that's kind of a funny shape The the pads you can see are also thinner because the Well, are the pins really that far apart from the other ones? 12345 12345 I think I think they're I think the pin pitch is the same. It's just that these pads are fatter I wonder why that footprint looks different than anyone All right, uh chip put it the right way around here. There was enough to sort of tack it down this one U38 So that is an s-ram So I'm interested to see how the the thinner Hads are going to work suspect the s-ram is probably quite Delicate It doesn't respond very well to being handled roughly by humans with their wet capacitive charged up hands And really I suppose I should be grounded when I'm doing this, but I don't know I can't be bothered. Okay. So the interesting thing about this chip Is that pin one? You can see is in the middle It's not on the corner. So That's why There's a dot here. Did I do that? But there's another dot over here. So in any case Oh, yeah, and and look there is uh in the corner So there's a pin one marker which is printed and then in the corner is uh where the resin mold was Indented so I guess that's two ways of telling which way the chip goes Oh, that's interesting. There's also this weird semicircle So that's three ways of telling how the chip goes They're really not fooling around and that's a good thing Well done ISSI Now it's important to get the pins lined up very well with pads Because they're quite thin so there's not a lot of room for error I think I ran out of solder on that one to add some more uh, you know Going over your pins twice I found is a really bad idea I think I just need more more solder. I guess I was a little Why is it really worth it? Okay, great So again the the key to this really is to make sure that you flux the pins As well as the pads because if you don't Then the solder isn't going to solder isn't going to flow very well Could do this next one 37 Now I don't have to do the capacitor next to it right now because there's enough room There's enough room down here Um, is this a lead based salt solder? Yes, it is you bet it is None of that lead free crap for me Besides I'm not like I'm not a little electronics factory So I'm allowed And besides it's not the lead that's bad for you. It's the flux fumes Just don't eat the solder And uh I guess for recycling, you know, again, you know, these are one-off boards and this is the least of anybody's problems. So Anyway, that's my justification What's yours they breathe lead free. Yeah sure Except you don't breathe the lead It's really a recycling issue. So the real problem is that when you throw these out Basically the lead goes into the landfill and then you know the Lead leaches into the land And possibly into the groundwater. So That's the real reason for lead free There's nothing to do with fumes have enough solder on that So sometimes what I like to do is just push down on the chip to make sure that I'm not holding it at a weird angle So if you'll notice what I've been doing is um Actually holding it on one pin and waiting until I see the solder flowing Then I sort of know that I'm at the right angle and I guess like Yeah, that I'm at the right angle and then I can just drag down So that seems to save some time. Uh, here's another one. Let's do that Recycling is a myth. Yeah Recycling doesn't really happen It all goes offshore and the sad part is Some of it just gets dumped in the ocean because money And here is where I could go on a rant about late stage capitalism, but I'm not going to I can't wait until we have nano fabricators Which I think is scheduled to come in around 2035 or so At least according to my profit Ray Kurzweil Extracting metals. Yeah, actually there's this guy on youtube. Um, I haven't actually watched him over a year, but he uh I don't know if if uh, I don't know what his channel is called even um I think I subscribe to to the guy's channel and I haven't seen like any recent videos in like a year or so, but Anyway, he takes uh, you know boards like this or equipment and he basically tears it all down to uh its components And it's like he takes the tantalum capacitors and puts them in a box and then he takes I don't know what he does with the electrolytex, but um You know, he'll take like the useful chips out and he'll put them in a box um He'll uh What else will we do? I don't know. He'll he does things with like the metals and stuff like that like like if there's a transformer on it He will take the transformer apart and melt down the wire for the copper And then just throw the copper in a box, you know, and and you know, you don't make any money out of it Especially on that scale, but you know, I'm sure but if you were to scale that up And if labor were free like it is in some parts of the world essentially You could make money off of it But it was pretty neat to see, you know how he Sort of took things just you know took things apart and showed you You know, oh here's some plastic and here's you know, this metal and here's that metal and You know, we can melt it down like this and he had a little uh crucible sort of thing going Or metal refractory or whatever you call it But it was pretty neat All right, um, here's a chip that I could do All right, this is u2 Which I associate with rock, but you know That's just me because I grew up in the 80s. That was me. I grew up in the decade of greed Greed is good Not that I believe that I'm just saying that that's what they called that decade All right, so there's u2 so now I do have to look up what that is because that is not a buffer Um, so if I just uh overlay this on top We see that u2 is a 7404 inverter So let's go grab the inverters Okay, here's one So I also had to be really careful To get the low voltage seamos versions. So this is an lvc It's important not to get a 74 co4 Because they're not really designed to work with 3.3 volts Not really. I mean, I I'm sure you could get them to work Like that, but you know, the voltage levels are a little different. So This one just says lc But it is an lvc. I know that So you can see that this one doesn't have a pin one a printed pin 1 marker But it does have the indentation in the plastic. That's just as good Have enough soldering here No, probably not. So the nice thing that I found about having a temperature controlled iron Especially Especially the hackle Hackle is that um Is that in the old days at least with my old iron? Um, you would put solder on the iron And if you left the solder on without cleaning it off, it would just basically burn Or I guess maybe that's not the solder, but the the Resin in the solder would burn and then it would ruin your tip And I found with these irons that you can just leave the solder on and it's perfectly fine Probably because the temperature is set correctly 330 So I do have a bigger tip with a bigger reservoir But I don't know. I think I think for these for these pins. This size is is the right size So speaking of hot air solder leveling um Okay, so first of all if you don't subscribe to strange parts on youtube subscribe Um, he has a video where he takes you through the jlc pcb factory Which is where I got my pcb from pcb is from um and uh I didn't actually know what hot air solder leveling was. I mean I I knew what it was, but I didn't know how they did it Well, basically they dipped the board In solder and then as they pull it up. There's like this fan that just sort of blows all the solder off Didn't seem very level to me, but apparently that's the way the leveling works So that's kind of neat Uh, anyway, the other coating is enig or enig Which is electro plated? nickel something or other um And that is what is recommended when you have fingers like this now you'll notice that these fingers are all Hazel And that's not great from a reliability. Well not a reliability standpoint That's not great for An insertion cycle standpoint. So if I put this into a slot and then pull it out and put it back in and pull it out Eventually these things are going to wear off and then the the connection is not going to be reliable an enig Coding is what you want for fingers like this and unfortunately You can't just enig coat the fingers. You have to enig coat all of the pads. So and then You can put gold plating on it, which increases the reliability by multiple factors So What jlc pcb does is they will gold plate the fingers But only if the coating is enig because I I guess well, you can't actually stick gold to solder. It's not a great idea I suppose Let's see what this one Let's do this one So I have to say this homemade fume extractor is working absolutely a treat And i'm very glad not to have spent the 75 dollars Okay, uh, let's take a look at what u3 is U3 is a 74 32. That's an orgy So let's go grab the 74 32s. First of all, let me put away These guys so I don't Have them hanging around Put them in the right bag Always be clean. See I have I have this roll of Of things and now I don't know what they are. Well, I do know what they are They're the 10k resistors, but that's only because that's the only resistor that I have So I should have put put them put them back if I could find the The bag there's the bag now they don't get lost And also it's a good idea to just have a cardboard box or a plastic Stir light bin to put all of your components in for one project When you're done with that project Um Then you can take all the components out of the stir light bin And throw them into a cardboard box Just for your component stash And it's important to label your cardboard boxes with what's inside Not every single thing that's inside, but you know, keep them separated like resistors in one box Resist capacitors in another box Say logic chips in another box memory chips in another box And come on everybody has a lot of cardboard boxes because Everybody shops it Don't them Anyway, yeah cardboard boxes are easy to come by so just use them. There is my little thing LVC this this one is an LVC not an LC So there's the little indentation mark Who's this from? I don't recognize the manufacturer Well, let me take a look at the label It says Next period it's an nxp part Interesting Why doesn't it say nxp on it? Oh, I guess They don't have to Why steven king solder things? Is this the first part of a joke? I don't know why does steven king solder things Trying to think of the punchline Because his horror is so metal Sorry the last two pins Okay, so here's a here's an example Of where I don't want to put These two chips down Or at least I don't want to put one of them down because this capacitor is right between the two chips So I won't really have room to slide it up and down like this I would have room to slide it this way, but I prefer to do it this way So I'm not going to put these two Chips down in fact. I'm not going to put any of these rows of chips down What I will do is put some more s-ram down There's one There's a protruding solder clump on one of the pins Probably on the one that I just did Probably that one, but that's okay as long as it doesn't like protrude across the pins I think that's what you're talking about It's a little hard to see now. I don't really see any bridges Let's see, you know, I'm looking at it through the microscope It's a little better to look at but No, that might just be the flux. So, um, let me just do a quick cleanup left side From there Again, let me clean it up Because it's sometimes a little easier to see When all the all the resin is not there Oh, yeah, I sort of see what you mean maybe This pin right here That isn't touching so I'm not too concerned In fact, I'm not concerned at all But, you know, I may as well try and get a little cleaner I guess I did it So, yeah, that works But yeah, you could definitely see Uh, see it a lot better once you clean all of the flux off So, anyway, yeah, it is it is definitely easier for for me to see the board simply because I'm looking at it in stereo And you're looking at it in mono vision Which isn't great but, um Yeah, but that, uh You spotted that tiny little thing really well. So obviously the camera is doing something for you Okay, uh, let's zoom back out and go to Let's say U28 focused U28 another s-ring flux Oh, you know what? I didn't I don't think I clean this off Yeah, I'll just do that now I also ordered from amazon You know when you go to the doctor's office and they have that neat little like alcohol dispensing pumps Just before they're about to jab you at something Sharp and painful. So I bought one of those um, I had to pay like seven or eight dollars for it and i'm like Surely I can get this cheaper from china Because really it's just a glass bottle or a plastic bottle and a pump So I went on ollie express And sure enough you could get them for like two or three dollars a piece But the shipping was the killer It basically brought the price up to what I would pay amazon to have it shipped two days prime so Yeah, I just bought it from amazon who probably bought it from the chinese suppliers Um, did I put away the chips? Yeah, I did okay So where are the s-rings s-rings Oh, no, there's nothing in the bag. I didn't clean it up. Um Well crap It shouldn't be that uh, here they are There's the dot. There's the dot. There's the dot And there is the dot. So this is the right way. I know how straight I got it. All right So I was holding this at I guess too shallow an angle. Suppose I should have done maybe this It's quite tight, but I think I got them all I will um There's a little solder here solder I'll just pick up. I'll inspect this afterwards. There's a solder bridge My first one. Let's focus in on that Let's focus in on that mistake And here's how to get rid of it First of all clean your tip You don't want to add more solder to a solder bridge. That's kind of stupid. Second of all Heat one of the pins up Let's heat this pin up. Sometimes that'll just draw the solder in And sometimes it won't The other technique is to just heat both pins up and pull That's not happening So the final technique is just to take some desoldering grade And put some flux on it and just press it against the pins Which is kind of dangerous when you're dealing with extremely fine pin fine pitch Oops, all out of its holder This can be dangerous when you're dealing with very fine pitch pins Because when you press you tend to damage the pins This actually seems to have left enough solder So I'm okay with this. I will go ahead and clean it now So the problem with such high magnification is that you can't really focus on the entire thing. You really have to Uh Select a plane of focus. So I think that worked out pretty well Let's inspect both sides Yeah, so I got one of those alcohol dispensing things from or i'm getting one from amazon And a bunch of kim wipes And I think that's better than these little you know cotton buds That's sort of We've cotton threads all over the place As they snag on things. All right. So The other important thing is and this is another reason why I got this alcohol pump thing Is that I just have the alcohol in a bottle and number one You take the lid off and you you tend to leave the lid off And then you know your hand knocks it over. The other thing is that isopropyl alcohol Um absorbs water So you never leave the lid off of an alcohol bottle Insert joke about drunks here. I'm really liking this this flux Again, I don't know if it's because it's new flux. What I really should have done is is gotten a new mg flux pen And then compare it the two Because it's not really a fair comparison to compare One flux pen that's old With one that's fresh On the other hand this one Oh, let's see. Where is it right here? It has a date of exploration So here's when it was manufactured May of 2018 And it expires uh two years later, I guess So and the mg pen didn't have any such markings on it, and I'm like um I know it's a little more expensive to have custom labels made like that, but uh, it would be really nice to Actually not have to make all that stuff down yourself So in fact, I don't know how old my pen is I don't know why that didn't go as well as as it should have Did I put flux on the pens? If I didn't then this would be an abject lesson on Why you should put flux on your pens I think I didn't put flux on the other on the other side So you could see how uh How more difficult it was should tell a story Okay, here's one I mean like, you know a thing that happened to me kind of story so So I got me a tesla I have a model three It's an awesome car by the way It's dual motor And it's so fast Oh my god. Anyway, um So I wanted to install a charger in my garage Because just charging off a 120 or 240 circuit doesn't give you A very fast charge speed because of the way the uh the current works, but Tesla sells A charger That it's basically a smart charger You know it can tell when it's plugged in You can set current limits all sorts of things And it's nice because you could set the current limit based on the the fuse or the the Current capacity of the circuit So anyway, um, I get it home and I'm like, you know, I know electronics And I've worked on hot circuits before hot 120 volt circuits. So I I know how to do this so I um So I already had a 240 circuit um and socket In in my fuse box and installed in my garage. So I'm like, okay, all I need to do is um is Pull the uh the socket out or uninstall the socket And wire up the charger So I open up the fuse box. I remove the uh the 240 fuse And I start pulling the wires from The socket out of the fuse box and you know, there's there's Four wires there a neutral two hots and a ground and the ground is just this, you know Solid copper wire So i'm pulling the wires out And all of a sudden bang And all the lights go out So what happened was As I was pulling the wires out the copper wire was flailing around and it hit the main bus bar And i'm like, oh, okay. I just blew the the house breaker and you know Usually the house breaker is right on top of the fuse box Or right above all the fuses in the fuse box if you have one fuse box and i'm looking and well, there's no house breaker I'm like, great. Now why? I'm looking all around to see if there's any other fuse box. No, that's it. And then I realize well, i'm in a condo And there's actually an electrical closet Where all the the house fuses are for for all the condos But it's a locked closet. So i'm like, okay. Well So how do I get in? Right, it's just easy. I just you know flip the breaker So eventually I email the condo association people or condo association is Maintained by you know, not people who are on site so I email them and I explain what happened and I say I need to flip the house breaker And they said, oh, okay. Well um We can either be there on four days from now when we're visiting And do you know and flip the circuit breaker for you? Or if you do it yourself Um Here's the combination to the key box where we keep the key And they kept the key in the same key box that the um that the common clubhouse Key is So I go okay, so I got the combination I went to the key box I opened up the key box. There's no key So I sent them an email with a picture of the empty key box saying there's nothing in the key box What the hell guys In the meantime, I was without power for you know a day by that point So I finally just decided to take matters into my own hand It's my own hands And I pick the lock on the utility closet in 15 minutes And flip the house breaker the end um coda the reason that the key was missing is that Apparently the person who had Been using the clubhouse Wanted to get in and out several times and just took the key with them Not realizing that there was also a key to the utility closet so Anyway, that's my story And I'm sticking with it All right. Well, I guess there's not really much else that's interesting on this board to do Like I said, I don't have the socket for these plcc's um Oh, yeah, so about the lockpick so um You know, I know how to pick locks So I was working on you know getting all the pins set correctly And then I realized that in my kit I had what's called a city rake And it's basically a a a wavy piece of metal basically That works to open cheap locks because what a city rake does is you stick the wavy piece of metal into the lock And then you jam it in and out and in and out and in and out And if the lock is cheap enough the pins go up and down and up and down and up and down And eventually they open So at first I was trying the you know single pin technique and that wasn't working And then I used the city rake and it opened in like a minute Or less. It was really funny. You know, okay. So anyway, like I was saying, there's not really much that's interesting here I don't have the sockets for for this besides. That's just through whole soldering. That's not very interesting You know, all that's left are a bunch of passives really and the rest of the chips So I guess I will call it um A day when we go ahead and I will call it a day and uh I guess that's about it. So Anyway, here's what the board looks like now So that's kind of nice. You can see that it's coming along quite nicely So all I have to do is solder one of these together and then a second one um, and then my Friend will be able he's written some python code in order to test this We use on the tester An ft 232h breakout board from adafruit And the annoying thing about the adafruit library that's supposed to be for it Is that it's only for python 2.7 and it's only for a very old version of the ftdi library Luckily someone has Has set up another github repository with the change that's required to get it to work with 3.6 And the latest version of the ftdi library Unfortunately, the latest version of the ftdi library isn't compiled for 3.7. So you're stuck with 3.6 Luckily, he does include Information on how to compile the ftdi library, which means that I could get it running in 3.7 Which I'd like to do at some point because I like using python 3.7 But Yeah, don't say oh python It's it's a perfectly reasonable language for writing quick tools in i'm not going to pull out my java compiler or my c compiler Just to write some tools Um python is a very high level language and there's nothing wrong with it Now if you would have said javascript, I would say uh, so anyway Um Interesting. Okay. Yeah, I don't know about the sci-fi sci-fi unit. That's a risk five processor There's an adafruit library for for sci-fi um Well, anyway, um What was I gonna say? Oh, yeah, so If you know a little bit about python, you could probably you know go in To the adafruit libraries and put some log statements in there and then find out what's going wrong and then fix it um So and obviously, you know between 2.7 and 3.6. There are a few changes Not a whole lot, you know just change print statements and and um, you know Be aware of the difference between byte and byte arrays bytes and byte array um You know and there yeah, okay, so there are some differences in the library But for the most part I haven't really found anything That's really really different. That's like completely incompatible Every every library at least that I've seen you know, that isn't insanely complicated You know will work between the two versions as long as you Take care of just a few things Where was I going with this? I don't know. Anyway, um, I think that's about it. So Thanks for watching So I appreciate all of you keeping me company for the past two hours well, okay So the microscope um If you watch the live stream that I did yesterday It's all about this microscope, which I just got from shenzhen and the camera that's on it So you might want to sort of look at that video I guess that's about it. So again, thanks for watching. Thanks for keeping me company And I hope I've kept you a little bit of company on this nice day In the bay area, which is now free of smoke from that awful awful fire So my lungs were we're doing some serious hacking and not the good kind. So anyway Take care See you on the next video and oh just before I go I don't have to show you a cat You know, it's about that time All right See ya. Oh, uh, what was the youtube channel again? Um, there was strange parts And let's see what other youtube channels that I mentioned There was one guy who did recycling. I have no idea. Just look for like recycling electronics And you'll probably find it As my latin teacher would say as I went off on another ranked about how much I love cats in latin Phelous I'm a phelous All right. Yeah, see ya