Synth DIY - Building a Digital Oscilloscope | Tutorial

today on under the big tree it's time to observe our oscillations by building the jye Tec DSO 138 digital oscilloscope DIY electronics is so much fun it's really relaxing you learn a lot and it's a fantastic way to be able to add to your modular synthesizer for less money today we're going to be building a kit that you can purchase from Amazon for about $45 it's the jye tech DSO 138 digital oscilloscope digital oscilloscopes are absolutely fantastic you can use them to be able to see exactly what's coming out of your synthesizer and it's really helpful to be able to troubleshoot with when you're working on other DIY electronic circuits and things aren't going the way that you think they should so you can take a look at this thing it's the size of a module it's not very big it's not very heavy it's not very expensive and it's all you need to be able to look at what's coming out of your synthesizer this episode is long and I mean long and at the same time there was a lot of stuff that was out of focus and the camera wasn't able to be able to capture everything that I did and so it's a little bit on the funky side I definitely apologize for that however having said that if you have never built a DIY module before or if you've bought this DSO 138 and you want to know how to put it together then have I got them video for you come sit down and watch me go through the whole thing we will sit there and identify all of the different components look at soldering techniques look at how to put them through the holes how to be able to test it test the voltage be able to see it actually work and then build this little acrylic box around it so having said that if you're still here then come on with me and let's go check it out okay so here we are and we're going to start putting together this DIY oscilloscope I know that we're primarily focused on doing synth DIY but there is no better way to be able to debug your audio circuits than to be able to have a visual representation of what you're seeing so we're gonna do this first I bought this kit for about $45 from Amazon and I liked it because it has the DSO 1:38 oscilloscope with all of the instructions you can need to be able to build this thing bit by bit and then it has all the rest of the parts as well it doesn't just have the circuit boards it comes with the mount to be able to have the different connectors to be able to plug into it comes with a power supply a wall where power supply and then it also comes with this nice acrylic plastic case so we'll be able to build the case as well as everything else and have the whole thing as one all-in-one system but the part that we're gonna focus on right now is actually building the electronics we have two packets of electronic components we have the primary circuit board you'll hear me call this a PCB board a lot PCB board or circuit board and then here is the little OLED display this is the visual graphical display that we're going to be able to use to actually see what it is that we're looking at one thing I want to show you about this it's it's the parts are very small but this is a relatively beginners DIY project and the reason that I say that is if you take a look very closely you'll see that all right it already comes with a whole bunch of components pre soldered on to the board so you can see here's a couple of integrated circuits and a voltage regulator and there are some resistor is there those components are super small they're very very very very difficult to be able to solder by hand but they're easy to be able to solder by a machine and they are called surface mount components or SMT typically SMT components are done by a robot although you can do it yourself and the kind of digital that kind of DIY electronics we're going to be doing is called through-hole construction it's the type of thing where we take these components that our hands can actually physically hold and be able to put them through the holes that you can see there all over the all over the PCB board so if you take a look really closely you'll see for example C 25 that's the name of a particular capacitor that we're gonna plug in and it's got a circle to let you know that that's where it's supposed to go and it has polarity so it has a plus symbol near where it is that you're supposed to put the plus side of the capacitor and there are a lot of things like that that will help you be able to plug the things in and be able to do it hopefully without making any mistakes and here is the back side of the PCB we take a look at this you can see that mostly all there is on here is holes that the through-hole construction goes through and we turn it around to solder them on this side so the first thing we're gonna do before actually doing any soldering is organizing all of our parts it's these parts are so small and you don't get more than just what it is that comes with it and so it's really important that you start by putting them in order so that it'll be really easy for you to be able to access them later I don't have anything that's exactly right but this will work it's a little overkill I have this gigantic 23 section storage case which is way too big but it doesn't matter it'll get the job done so the plan here and the nice thing about it is when you stop working halfway through your project and leave you leave everything in here and then when you come back it's all ready for you to start again so we're gonna take a look at all of these components here that we're gonna need to be able to sort and we're just going to open this up and pour them all into this very convenient little but right there to be able to allow us to start sorting them this is the BNC connector that our probe is going to attach to and then we have some little plastic building materials and so forth all very straightforward to organize what's going to be a lot trickier though is organizing out these small components which are really the meat of what it is that we're doing here so we have these electrolytic capacitors we want to look at them and make sure that the ones that are going in the same the same little pouch are all the same value this one for example is a hundred microfarads 100 UF and that one is two these are both 100 micro farad 16 volt electrolytic capacitors so we can put them together into a box and we'll know that that's where they where they belong there may or may not be other caps that look similar that are different values the trickiest part for us is going to be identifying the different resistors so these are a series of different resistors that we have and a resistor is something that resists the flow of electricity they're extremely common you're they're used all the time and every DIY thing you can imagine and if you look they have sort of these little tiger stripes on them and those aren't just for decoration those tiger stripes actually are color coded and allow you to be able to visibly see what the color values are of these resistors by looking at it but my eyes aren't that great and you know I haven't done it that way for a long time what I'm gonna do instead to make sure that we know exactly which the right ones are is that I'm going to measure them using the multimeter instead I'm gonna measure the resistance of each of our resistors and put them in cases together with them or just put them in little pouches together so that we absolutely know we're not putting the wrong resistor into the wrong spot so let's take a quick look so I'm going to turn on the multimeter so we're gonna take our own meter and we're gonna put it maybe into the middle well we'll set it it's got a bunch of C it has a series of scales and so you use those scales to be able to zoom in and see what the particular resistance is of the value of your resistors because there's a enormous breadth from you know fractions of an ohm all the way up to hundreds of millions of an ohm so we're gonna take this now resistors are not polarity sensitive so it doesn't matter which side we put the black and we put the white on it does matter when it comes to capacitors though so take a look at this it looks like we actually guessed right right off the bat so I set the scale to 200 K or 200,000 ohms and it looks like this is exactly a 200,000 or or 200k ohm resistor we just happen to guess correctly I'll move it up to here to two million and we'll see that yes indeed it is in fact a 200k ohm resistor if you go below it so it's 200 kilohertz or two hundred kilo ohms and then I move the the and then I move the scale to 20 kilo ohms then it just goes off the scale it can't read it and so it just comes up with a 1 there and that's why we need to do the scaling okay it's about 10 minutes later and as you can see I've organized all of the resistors I've actually organized all of the components and I'll show you the rest of them in the storage case after I get all the resistors done there were so many of them that I thought I would take a little shortcut and just take a piece of paper and as I measured the resistors put them on the paper writing down exactly what their value is we're gonna start setting these up and I'm also going to show you what the naming conventions are for the values of the resistors okay I wanted to take a little bit of a digression and talk about the nomenclature of resistors every time you work in some new field of course it's always got its own lingo Electronics is certainly no different than any others and so there are a few things you have to know about when we're talking about the value of resistors so resistors are measured in ohms and resistors can have anything from zero ohms which is a straight wire all the way up to you know hundreds of millions of ohms so the symbol for an ohm that you will see at up attach two resistors often is the Omega symbol it's just like that the Greek Omega but in order to be able to make it easy for us to be able to see what the value is of a resistor at a glance they have evolved a system that uses three letters and those letters are our K and M so M stands for millions K stands for thousands and R stands for ones I don't know where it is that art comes from but it's very useful so I'm really glad that it's there so for example if we have a resistor that is 180 ohms then you could read it as one eight zero R which is easy to see if it's a hundred and eighty kilohms or one hundred eighty thousand ohms then it's 180 K and if it's one hundred and eighty mega ohms or one hundred and eighty million ohms that's right you guessed it it's 180 m as soon as you see those things with or without the little Omega symbol next to them you'll know what it is that they are talking about so you can have this but it is not necessary because the context of what it is that you're looking at tells you what it is that you're talking about now there's one other piece of this that I really like as well but it may look a little funny at first so it's important to understand and that is this let us say that we have something that is not an even number like that let's say that we have something that is 1,800 ohms and we wanted to be able to display that in a little bit of shorthand well 1800 ohms is the same thing as 1 point 8 K or one point eight kilo ohms and you may indeed see it like that but there's another way of showing the same thing that I think is a lot easier and less ambiguous to see and what that is is that we take this letter here and we actually put it right in there where the decimal places so instead of saying 1 point 8 K for one point eight kilo ohms which is correct you can say 1 K 8 just like that and it's one less thing to make a mistake on and those periods can be a little bit difficult to see so you don't have to worry about that so I don't think I've ever seen this with ours but I see this with kilohms and mega ohms all the time so 1k eight right so a 2.2 mega ohm 2.2 mega ohm resister would in the same way be listed as 2m 2 because the M has gone over there to replace the decimal point so 2m and that's a 2 not a Z all right let's get back to building an oscilloscope shall we okay we're going to start stuffing the resistors into the PCB and the way that I like to do that is by using this trusty device here which is called a pan of ice it's got these arms here to be able to hold my PCB board so what I do is I take the PCB move it over here I just these arms till it's almost tight and then when I flip this boom this little spring action and it holds it in place just fine and quite gently so what I'm going to do now is start stuffing some resistors now fortunately for us because this is sort of the beginners kit they give us a little check my little checklist of the names of the different values of the resistors and the slots that they go in so the 100 K resistors go in R 1 R 14 and R 16 so this becomes sort of a game of Where's Waldo a little bit where we take a look on the board and we look for R 1 okay so there's our 14 right there and we know that that's a hundred K resistor now there's a couple of different ways to do this part you can bend your resistor leads with you know a little plastic template that you can put it on but for something like this I think it's easy enough just to bend them and put it in place so I'm gonna gently bend the leads a little bit like that come over here to where it says our 14 and put them through drop it down so everything is fine sometimes I've been to leads back in the back so there's no way that it can come out so there's our 14 let's do the other hundred case so that if we stop we know where we are so we're looking for R 1 and R 16 okay so I'm gonna do the same thing I'm gonna stick our one into the R 1 slot and the most important thing about this is that this is meant to be fun and it's meant to be relaxing at least it's relaxing for me and so I never am in a hurry and I just go along and I double and triple check everything and the result of that is that the most stressful and frustrating part of this which is debugging is left to a minimum doesn't mean there won't be any but there will be certainly less stairs r16 all right and I'm gonna do the same thing I want to make sure that the resistors are is flat as I can make them against the board so now that I finish those three I'll just go right up here to my check list and say boom you're done get out of here so the rest of this is more of the same so I'll shut off the camera now and all I'm gonna do is stuff all of the resistors into the board I'm not going to solder anything yet and then I'll turn the camera back on when we're ready to solder okay we're back and at this point I have now stuffed all of the resistors into the circuit board as you can see they are all as flat and tight as possible against the board and everyone is painstakingly in the correct location where it should be I'm gonna show you what it looks like from the back here's the thing so there are all of the there are all of the leads in the back and I've tilted them a little bit to be able to have gravity help hold them in place I'm actually gonna turn it over and just start soldering here on the table and the reason is because that will allow me to be able to have the table push up and hold the resistors in place as we go okay I've turned on the ventilation fan to be able to get the flux and solder residue into the fan and away from my lungs which is a good thing although it'll make it a little harder to speak over the noise basically this is the way that it works so you you hold the PCB board you heat the pad and the component lead not the solder and then you hold it in place until the slaughter wicks into the hole creating a smooth and even cone I'm going to do a couple more and then I'll turn off the camera and continue this and then we'll take it up after that all right all of the resistors have been soldered and clipped onto the PCB board the first transport is away yay so let's take a look here let's try to look from the side the best I can do it all done there as best you can see unfortunately you can see that all of the resistors are lying flat against the PCB they're not absolutely perfect some of them are riding up a little bit on one side versus the other but they're all flat against the board and they are good enough for a homemade bit of DIY the important thing is that none of them are touching and as we look down at the board on the bottom side it's really critical to see that none of the solder joints down there are touching they're all relatively even they all look relatively the same they're all shiny and they all or nearly all of them are a little volcanic sort of cone doing that ensures that we won't have cold solder joints and it ensures that we don't have solder bridges or clumps of solder that go between different components on the bottom of the board which cause things to short out okay so here's the toolbox that I put the rest of the pieces in it's too big but it made it quick and easy for me to be able to sort the different components which will make it much faster and less prone to error when I actually put the things into the PCB board okay so the next thing on the list are a series of chokes or inductors they look like resistors but in this case they're a little bigger and they go are in the l1 l3 and l4 category they've got a line with a little sort of double squiggle so put those in okay check those off now the chokes are not polarity sensitive but next up are the diodes and they absolutely are so if you put a diode in in the wrong way it will not work so here is a diode and I'm not sure if you can see in the camera but there is a silver band on the right-hand side of the barrel there but you want to make sure whenever you're looking at an image of a diode that the silver band lines up with wherever it is that there's a small stripe there the five eight one nine goes into the d1 slot and then the other one is supposed to be a four zero zero four or four zero zero seven so that one is going to go into the slot for d2 which is right there and it says one four zero zero four on it so those two are done and next up we have a crystal here is this little teeny tiny this is the clock of our system it's an eight megahertz crystal I think this is a good time to solder those units up and then we'll go back to adding more parts oops okay all of those components are in and I've checked them they're flat so once again we're going to take our pair of diagonal cutters and clip the leads down snug looks pretty good so as you can see we're building up more and more of the pieces the diodes have the stripe matching the stripe the there is our oscillator our crystal clunk and our inductors so it's time to move on to see what's next okay so this next part is going to be challenging this is the USB port that's going to be connected to the circuit board right there and you can see that is pretty challenging those those little pads are very very close together this is almost that stuff is almost surface mount level so it's gonna be a bit of a challenge but you know we love a challenge so the first thing that we need to do is make absolutely sure that the pins themselves are aligned properly I'm sorry for the bad camera work but they're a little bit out and so I'm going to take needle nose pliers and try to adjust them so that they all line up that's better I certainly have my magnifiers on and now I'm going to try to line all of these up and you'll know when it works because they'll all pop in place just like that all right so let's take a look on the back that's where it is and you can make absolutely sure that all five of the all five of the leads are all going through the right place these are all probably ground pins these bigger ones we're going to solder those in place and then we'll have to go through and be very very gentle and careful to get those five small pins without them touching each other now for stuff like this just as a matter of course I often just use the edge of my pliers to be able to hold this down and keep it in place so by doing that the unit that I'm trying to solder up is above the level of everything else and so I can push down on it very gently with my fingers to hold it in place as I start to solder it up you interesting it's not wanting to a fix to those tabs because they're all grounds and therefore the heat is getting dispersed among the entire system so we do have a solution for that it's called a flux pin here is a flux pin and this is merely used to put a little bit of the flux that's inside of the solder itself onto the PCB board to aid in the flowing of the solder so I'm going to just dab a little bit on and we're gonna be cleaning all of the flux off of the board when we're done with some isopropyl alcohol but I will bet you that's gonna help move everything along okay we've now managed to get the four pieces that are holding the USB thing in place and we're just going to use a chem wipe to get rid of some of the excess flux that we ended up putting on the surface doesn't matter because we'll be cleaning that all up later with alcohol but don't need to have any more on it than we need to but that's now nice and tight we're gonna use a little bit more of the flux to paint the five pins that are really the business aspect of this whole thing so much more gently than I did before there we go just the smallest amount to help flow the solder so the way that I'm going to do it since I'm left-handed I'm gonna start since I'm left-handed I'm gonna start with the bottom left pin work my way up so that I'm not reheating any pins that I've already done and then I'll turn the whole board around 180 degrees to try to get the rest of them so when we're working particularly with really small things like this it really pays to plan ahead so here we go we now have five of these little buttons that need to go onto the board they're not polarity sensitive they're a rectangle and you can see down there the rectangles themselves they have kinks in their leads so that they'll stay in place snuggly once you put them in and it's a matter of just working them gently in and then they'll hold and you can do all of them you can solder all of them at the same time there we go there's the first one all right all five of them are now in you can just turn this thing around and there they are all waiting to be soldered [Music] [Music] and here we are with all five of the buttons soldered neatly to the PCB okay the time has come to take a look at the weird nomenclature of capacitors like resistors they have their own vocabulary and you just have to get used to it it's not that bad though the primary unit of measurement in a capacitor in terms of how much charge it holds is the farad one farad would be written like that one F now a farad is an absolutely gigantic amount of charge we don't work with anything anywhere near that when we're working with electronics like this instead we're working in terms of units like micro farad's and pico farads so a micro farad is equal to one one millionth of a farad so micro farad one one one of a farad similarly a pico farad is one one millionth of a micro farad now a micro farad is shown in terms of you F and a picofarad is shown in terms of P F just like that you will see micro farad's quite a bit in electrolytic capacitors however they're really really tiny capacitors that just hold a little bit of charge like these tiny ceramic capacitors that we're about to put in those are usually measured in terms of Pico farad's now in order for them to be able to get all of these huge numbers onto these little teeny tiny ceramic casings they have to come up with a system of nomenclature that is a little bit confusing but it does work let's pretend we are trying to represent 33 Pico farad's the way that this would work is that 33 Pico farad's would be represented as 3 3 0 so the first two numbers the first two digits are the primary value of the capacitor and then the 0 over here this digit right there is how many zeros it's multiplied by all right what so here's what I mean so let's pretend that instead of seeing 3 3 3 0 this said 3 3 1 what that would mean would be that we would have 33 times 1 plus 1 0 equals 330 Pico farad's if this was a 2 then it would be 33 times 1 plus 1 0 2 zeroes equals 30 300 picofarads oh and when you have teeny teeny tiny little things like 3 Pico farad's they just mark it as 3 we now have the situation where we need to figure out what the values are of all of these ceramic capacitors that we have to put into our oscilloscope and so in order to make it easy we're gonna write down what those values are first so we're gonna have some that are 0.1 micro farad's some that are 330 Pico farad's some that are 3 Pico farad's some that are 1 pica Ferren some that are 120 Pico farad's and some that are 22 Pico farad's so if this is the value then what is the number that is listed on the ceramic capacitor well 0.1 micro farad's is number 104 so in other words that's one times ten with two times one with four zeros equals one times one two three four ten thousand so this is the same thing as 10 thousand Pico farad's 330 Pico farad's is the one that we showed before it's 33 with a one because it's 33 times ten okay three Pico farad's is 3 1 Pico farad is one 120 is 121 so we have 12 + 1 0 22 Pico farad's is going to be 2 2 0 in other words no zeros that are it's not multiplied by 10 or anything and therefore it's just the 22 itself hmm if this is too difficult to remember and goodness knows I barely remember it just go to the internet and look for a capacitor number chart and you will find all of this information okay now after that exciting capacitor diversion it's time to actually put the ceramic capacitors in where they belong we have a whole bunch that are 0.1 micro farad's so we're going to save those for last and we're gonna do the other sort of the less common values here first so that we don't stand as much of a chance of making a mistake with them and I'm gonna pick up the first one and the first one is three three one which is three hundred and thirty Pico farad's and that goes into c2 now one thing about ceramic caps is that they're not polarized and you'll see that the symbol just looks like two little sort of backward T's back-to-back the polarized caps like the electrolytic s-- you'll see a little plus symbol or sometimes a little minus symbol next to one of the poles reminding you that you have to put the cap in that way okay now finally it's time to put in the zero point one microfarad caps these all say 104 on them and fortunately they're a little bit bigger than those other ones so they're a little bit easier for my big hands to handle so there are 11 of these they go into c1 they basically go into all of the slots that are left for ceramic capacitors there's c1 I'm going to turn off the camera put these ceramic caps in and solder them in the back it's exactly the same as all the other components we've been soldering and then I'll be right back alright well we are done getting the ceramic caps on you can see they give a little bit of depth to our little oscilloscope Valley here it's looking pretty good all of the connections on the back look pretty clean and pretty solid I don't see anything that any solder bridges or anything like that yet and so it's time to move on and start putting more of the components on okay we're gonna put in a few one offs right now the first thing we're gonna put in is the single LED that's on the board like the other kinds of diodes an LED or light emitting diode is definitely polar in this case with an LED you can always tell the positive side is the one in which the leg is a little bit longer it's sometimes heavy has a flattened area on the same side of the physical LED casing and if we look down here at where the LED is supposed to go the positive side pad is square and the negative is circular so there's two or three different ways we can tell the right way to be able to line up our LED if we put it in backwards that'll be the end of that LED there's the LED now we have a little power coupler this is supposed to be put in with the facing outward and if you take a look here closely you can sort of see that there's a stripe there that helps you line it up with the way that it actually physically is supposed to be in there so and that goes and then we have two of these capacitor trimmers which are also strange fairly uncommon little devices if you can look and see there's a flat side and a circular side and if we look here about where they're supposed to go on the board we can see that there's a flat side and a circular side so they're telling us the right way they want those guys in okay now it's time to put in all the electrolytic capacitors so just like the L the LED the light emitting diode these capacitors the longer and lead longer and lead is positive and also with these you can see the negative side has got a little stripe with a negative on it so if we go over here and take a look at C 24 for example we can see a square pad with a plus and so that's where the positive side of the cap goes okay I'm gonna finish these up solder them up and I'll be right back all right well all of those components have gotten onto our ever expanding oscillator board here lots and lots of holes have been filled in that one thing I wanted to show you right here Oh No let's see if the camera can show that it is a it is a solder blob so that is a place where I got too much solder on it and the two leads are connected together which will not work so I'm going to show you how we get rid of that there are a number of different things we can use we can use solder braid which is one good way to do it that's a good way to sort of stop up a bunch of solder and we can use our solder sucker or vacuum pump I think for this I'm gonna try using this solder sucker the other way when you're working with surface mount particularly components you can also just get in there with the with the soldering iron in between where the solder braid is and just sort of flick it out of the way just sort of deftly get in there and flick so I'm going to I'm going to blob it up again so that I can use the solder sucker come on roll up okay there we go darn it being so efficient alright now we're gonna try doing the same thing with the solder sucker I'm gonna put the solder sucker right there on that side and then come in here and heat it up on this side and once it's that all there is to it so that took off the solder bridge but it also took out some of the solder that was being used to hold a good joint for that one leave there so I'm going to resolder it there we go solder bridge fixed alright we are now in the homestretch as far as the passive components go in terms of building our oscilloscope the last four things that we need to add are right here in my hand these are transistors and voltage regulators so the tricky thing about transistors is that they all look exactly the same they're you know a little black piece a little black Halfmoon piece with three legs there's only one Durrett way that they go in of course the the polarity is really important they all look the same and the only thing that's different is some very faint writing on the flat side of the transistor so in the case of this particular build there are two transistors and two voltage regulators all of which are different and all of which are look exactly the same and so we have to be triply careful to make sure to put the right ones in right in the right spots so let's start with the first transistor so if you take a look here you can see the organization the the way that you should actually put the thing in and basically a transistor is an amplifier very much like the vacuum tube before it but it's a whole lot smaller and uses up a whole lot less power there's the collector the base and the emitter the idea is that there's voltage coming in voltage coming out and a control signal that tells you how far to open the spigot there we go super you see super useful of course and transistors are still it's still in use even though integrated circuits are much smaller and much more efficient in terms of jamming a whole lot of them on there at the same time now the one thing about transistors is you really want to be quick about soldering them you don't want to hang out applying heat to the legs for too long because you could potentially damage the transistor I've never done it but I'm sure you can at least I've never knowingly done it so the more I work on this design the more I realize just how flexible and well-designed it really is for example here is the power section of the board it has both a header for a DC 9-volt system but it also comes with an AC adapter and this power header right here so we are going to attach that there and then we will have multiple different ways of powering this bad boy next we have some pin headers to put in now these that come in a long strip like this and what we need are three of them to go into that hole and four of them to go into that hole so all you do is you take your diagonal cutters and you say alright well I want three one two three make sure that you're not pinching anything give a little snip and there are our three now we'll do the same thing with the four pin header there and this time we have four pins stick it in okay next up are these female headers that we need to add there are two of these little teeny 2-pin female headers they just fit right in to the board like that then the last one is this gargantuan pin header this 20 pin header here that is going to be connected to the to the display so the male pins are in there at the same time so we're gonna pull those out just to make darn sure that we solder solder it the right way in very gently disconnect back and forth last thing we want to do is have to go to the electronics store I can just very gently push up on the pins all the way around and be able to disconnect it anything there we go okay so this is the male header piece that's gonna go on the monitor on that LED display and this is the female piece that's gonna go right there so the first thing we need to do is look for any bent pins and adjust them into place and there's one right there right at the edge we need to bend those back so that everything is square so we can get it in now what we do what I do once we get it in there we're gonna put it down and I am going to go solder one pin on each corner the reason is because that gives me the ability to make sure that it is flat and tight against the board so I'll start with this pin you have to make sure that's the case before you start soldering a bunch of pins because if something's wrong and needs adjustment and you've already soldered eight pins down then you're out of luck all right so that was our first corner and I take a look very carefully and I can see that it's pretty flush now I've soldered that corner and that corner and I can look up here and see that it is perfectly flat against the board it's just right and so now we're ready to go and solder all the individual little pins now this is obviously a place where solder bridges can get in get involved if you're not careful and so you have to make sure they don't as I said the technique that I like to use is this so I'm left-handed so therefore I go here to the left side and I'm gonna start right here between these two pins on the bottom and the reason is because I don't care if I hit this pin with the soldering iron I'm soldering this one if this one already had solder on it then I could make a mess and causes a blob of solder and so forth but because I do it this way I can just solder them one pin at a time and work my way up so now the one that I soldered is not being touched by the soldering iron so I can just solder the next one and continue just like that now so now you can see that I've done about the first four or so I'll finish those up when I'm done I will physically turn the border on this way and do exactly the same thing going in that direction so whether you're left or right-handed this technique is a really good way of being able to solder all these little tiny pins together with minimizing the amount of time that you can spend accidentally resolder in or heating up something that you've already soldered so I'm going to turn off the camera do that offline and I'll see in a minute okay forty solder joints later we are done you really get into a flow with this stuff huh right in the pun once you once you get into it and I was able to get them all done every one of them is neat and clean no solder is bridging from one to another they all have that nice little sort of conical blob and this is completely tight so the next thing and we really are coming towards the end of this part is putting these switches here on so these switches are polarized so once again I'm going to take a look at this guy before we try to put it on and see if there are any bent pins which there are and so rather than trying to fix it later I gently bend it back into shape and then take this and gently try to get all of the pins onto the PCB board so they all line up there's nothing worse than putting it in and pushing it and bending a pin that wasn't actually ready to go but in this case it looks like they're all there and so I can gently push both sides of the switch into place and it fits like a glove without even soldering it makes a really good strong connection okay all three of them are now connected and now all I have to do is solder them just like everything else that we've done the same technique alright well all of those got soldered everything is good we are now to the last task page1 whoo-hoo which has attached this BNC connector in the this is going to be the device that the the probe connects up to in its really thick metal and it says here note the thicker pins need to heat up longer to get good soldering result so agreed but we will also take out our friend the flux pen and yeah the little flux going on there to be able to help convince those thicker pins that they that they need to be soldered now I push the BNC connector down really strongly onto the thing so that there's some physical connection as well because this is going to get connected and disconnected a lot and so we certainly want to make sure that it is really really strong as strong as a stronger connection as it can possibly be so we'll start with the thinner of the thick pins yep that's good I can see that there's solder all the way through and up on the other side so that one's good now we have these two thick metal ones that are connected to the outside of the BNC connectors so I am just gonna be very patient and sit there and just wait for a few minutes well for a few seconds anyway for the pin to heat up and see where we go I think I'm gonna turn up the temperature temporarily see if we can use that to convince this pesky BNC connector to be our friend now we got it so take a look here we can see that it's got two nice big solid shiny connections so that BNC connector is not going anywhere Wow and that's the end of page one it's looking like one mighty fine and mighty busy piece of piece of circuit board there let's go over to page two there were only a few things before we are actually ready to begin testing so we are going to take one of our leads this is gonna be a test lead make a small ring with it and then we are gonna connect it in to j2 then it says two short jumper three with solder there is jumper three so if we take a look right there there's that little surface mount pad it's already got a little solder on it and they want us to it just jump that purposely create a solder bridge to make a permanent connection there now we have to put the connections on to the back of the LCD board so we've got a header connection with I believe 40 pins that has to go right there and then a couple of two pin connections that go there and and those things are what we're going to use to connect the LCD board to the oscilloscope just like that the first thing we're going to do is do the big long complicated one it's in and it's completely tight I'm gonna hold this down here and just like on the other ones I'm just gonna solder down one end on each side one corner on each side and make sure that it's that the connection is really good and then I'll go through and solder the rest of it up as a first one so then I'll do the other one kiddy Korner to it there we go so now we're gonna do these in order and I'm gonna start with the inside because that looks like it's gonna be harder to gain access to so you think ahead if I take the soldering iron and I go this way then it doesn't matter whether I heat this pin again or not because it isn't soldered yet and so I'm not going to have to worry about I'm not gonna have to worry about creating solder bridges or anything like that so I'm just gonna start here and work my way up all right that looks really clean no solder bridges everything is a sort of the well-formed volcano except maybe this one looks really good okay now I'm going to start the outside series okay now we have these two little jacks that we have to put in on the other side of the board right there and there they give us four of them so we're gonna use our diagonal cutters very carefully to clip right in the middle between them alright this should be a piece of cake alright that is it for the soldering for right now and now it's time for us to check the voltages on the main board and see how it is we're going to check to see if the initial voltage is correct we're going to do that by taking this 9-volt power adapter plugging it in all right so now nine volts of power is coming into the board and then we're going to take our probes from our multimeter which I currently have set to checking for a DC voltage which is what we want and it set it a maximum of twenty volts we know that we're gonna be looking less than that so that scale is good we're gonna take the black and attach it to the ground point that they have right there and then they have a little point here that says plus three point three volts and we're supposed to attach red to that to see and as we can see on the multimeter we've got three point two nine volts so I'm gonna call that a win now the next thing we have to do once that's done is there's a little teeny-tiny solder pad there JP for that we're supposed to solder together I presume that'll bring some other voltages in line we will find out there we go alright next step is to attach this board time to attach the TFT board put it all together make sure that all of the everything is in place where it should be and it all fits like a glove we have a little sandwich there and it all worked out now comes the scary part let's see if it turns on ah look at that so it all looks like it all worked incredible so now with all those Basics in place let's attach the probe which is a single BNC connection ok let's see if we can see anything ok so the moment has arrived here we are you can see that I've got a plug plugged into my sto oscillator and we're gonna follow it down to here where it connects up to the probe which then goes into the oscilloscope and then shows us that woohoo so it does appear to be working I'm going to adjust the frequency on the oscillator and look at that just if you'd expect as I turn it slower and faster the waveform changes appropriately let's try plugging it into a different wave shape there we go completely different looking wave shape let's go over here to a there we go here is a dip for a VCO we're plugging into the sawtooth and as I tweak the tuning it changes it a little bit and of course as I change the range of the tuning it'll change quite a bit cleanly here's a triangle wave and a sine wave and look how different the sine wave looks coming from the deafer then from the sto totally different looking sine wave but the good news along these lines is that it all works and hooray now all I have to do is build the box for it and I'll be all done ok the last stop on our little train ride of oscilloscope building is to create the the Box the casing that the thing comes in the version that I bought came with the casing but I managed to break it to the point where it made more sense to buy another one and since there were only about $8 it's not a big deal there are these sort of neat acrylic clear cases but you know when they say acrylic I had visions of bulletproof plastic and what they really meant by that was clear plastic so there are a couple of engineering faults in it that you have to be very careful about when you're actually building it or you'll be buying another one like I did specifically right here that and that are two points where it's extremely easy for them to snap like a twig and then you have to do it again so we have a whole series of bizarrely shaped pieces all of which have got this this this paper on it and so the first thing that you have to do is go through and remove the sticky paper from both sides which takes a little bit of time then you have to put it together the shapes are so weird and it's so unintuitive that there's no way you can do it without the instructions but fortunately the instructions are available on the web and so it's really pretty clear how to actually do it so I'm gonna shut off the camera and take all of this paper off and then we'll be right back okay that highly tedious job of peeling off all of the paper is now done so we have these weirdly shaped pieces of plastic so let me show you basically how it works the thing that you start with is the TFT screen which connects up to this piece here and you have to make sure that you do it in the right orientation for the buttons and sliders to be able to connect up to that the way that they should and even that's backwards there's only one proper orientation here it is so you set that up to make sure that everything lines up properly and then you're gonna put that on there we're gonna start by screwing this piece on to there and then we attach these plastic basically switch and button extenders into these slots so these things are gonna go on top of each of those and these pieces here are gonna go on top of each of the buttons and so that all happens then once we put these sliders on then we put on two layers of this thicker of this other piece of acrylic again with everything lining up properly two layers basically just to make it thicker I think is what they designed and then finally there's one more piece of solid plastic that goes over the whole thing and that completely covers the the TFT slot piece then finally you put these four pieces all the way around the sides and then here's a piece for the bottom and then you're all done so let's get started okay so we get started by confirming for the fourteenth time that the orientation of this of this piece of plastic is correct with the oscilloscope main CPU the main PCB and once we're sure of that we use these teeny tiny little m2 screws to be able to attach the TFT directly to this board okay I finished getting the screws in and then used a little microfiber cloth to wipe the top of the TFT screen because of course there's you know oil and fingerprints and stuff like that and so you want it to be as clean as possible so then I'm taking these three sliders and putting them in there and then these five button extensions and putting them in there like that five okay now we put these pieces on top making sure that everything all of the other cuts are lined up which they are and then we do the site same thing with the second one there we go and so then we take this top protective plate and we do the same thing and we there we go again there's only one orientation that works so save yourself some time and hassle by getting that right so that all looks good so now that that's in place we get to take this whole sandwich and attach it to the CPU of the PCB board so very carefully making sure that all the pins go in the right holes okay so I've made sure that all of the sliders are connected to the switches and that all of these things are in their proper location and all of the pins are right so then I can push it down and we've perfect and we've got ourselves a little acrylic sandwich so now that we have this gently go get these long screws here and run them through and there's gonna be more of the screw sticking out the bottom because we've got these nuts and then we've got these end caps and the nuts are to finish putting this sandwich layer together and then the end caps are gonna be when we put the rest of the box around it and I'm not gonna bolt these in too tight because if I do then it's gonna start squeezing and putting pressure on the circuit board at the edges and we don't want that because that could have eventually resulting broken solder joints and general mayhem okay I've got them all on I'm just going to do one gentle tighten of each one just down there until I don't feel any pressure until I don't feel any looseness but no tighter than that so there we have the primary there we have the primary piece of our whole thing then we're going to attach the other four sides and then the bottom and then we're done okay I made one little mistake that requires a small tweak which is namely that this side piece you need to have a little bit of play to be able to get it in there otherwise it won't fit and so you can't do it while the while everything is tightened down so I pulled the bolts out just a little bit just about half way to give me a little bit of room so that I can then take this piece of acrylic and slip it in and have it fit over the BNC connector alright so once that's done then you can tighten these down again because the rest of them the rest of the sites just slip in place so I'm going to do again it just a very gentle tighten of the bolts tightening of the bolts yep still work if you tighten it too much the buttons will be crushed against the the button tops will be crushed against the buttons and then they won't be able to work they won't be able to push down okay everything is in place that's connected I've confirmed that these switch tops are still connected to the switches because it's easy for them to be able to fall out of alignment and now we just put the rest of the pieces in like a little like a little log cabin okay so now all of them all for the sides are in there's a the USB port is available those things are connected the right way so we know that we have the orientation of this whole thing correct now we take the bottom nope this way and gently put it in place and it all fits together like a nice Dagwood sandwich so at this point all we have to do is screw these and bolts on make sure yep you screw these four end bolts on and we're done and we're done all right let's take it upstairs and plug it in and make sure that still can read what our synthesizer is you're telling it then we'll be all finished okay and now finally it's time to test this bad boy out so here we have the oscilloscope I'm going to take that off so I'm going to take the oscilloscope it's plugged in over here with power and then I'm going to take the BNC connector attach it up and then I've got the connections going to the tip and the sleeve of this regular old 3.5 millimeter cable and let's plug it in to the and let's plug it into the sto let's reboot the thing okay it's up and running whoa look at that a sine wave and as we change the frequency we get exactly what we would expect I'm gonna pull it out stick it into this other one ooh look at that interesting that interesting waveform so you couldn't ask for better this is absolutely perfect it's exactly the right size to be able to use for troubleshooting your synthesizers and stuff it's tiny it's cheap what's not to like well thanks a lot for watching through all of that I really appreciate it I hope that you learned something and that you're excited about building your own digital oscilloscope and you feel empowered to be able to build your own stuff that's it for this episode of under the big tree as always if you like what we're doing please feel free to like share and subscribe for now this is Nick signing off

Channel: Under the Big Tree

Views: 5,119

Rating: 4.8947368 out of 5

Keywords: DIY, Eurorack, Synthesizer, Music, Composition, Recording, Performance, Analog, Sound Design

Id: bpV74ixz8eU

Length: 74min 1sec (4441 seconds)

Published: Mon May 28 2018