 I have some new bags so what these are are two cheap and fairly generic electronics kits from Geekrite costing about $10 apiece. This one is a frequency counter used for measuring the frequencies incoming signals and this one is the thing that goes with it which is a signal generator. Today I am going to open these up, take a look and assemble them. So this is likely to be a long and rather boring workbench video. However I have not opened these so I will be doing this completely blind. So that will be interesting I suppose. Anyway let's start with which one looks more interesting. Let's start with the signal generator. What have we got here? An anti-static bag. This is the case which is acrylic supposed to peel the paper off which is why everything is brown. A PCB, a double-sided PCB with rather small pads. That's interesting. And this should hopefully be the instructions. XR 2206 function generator manual install. So we have a picture of the PCB, a parts list, C1 electrolytic capacitor, 100 microfarad, the positive long feet. Yeah this came from China. The welding installation considerations follow these steps. The components are welding the front board from low to high principles namely the first low welding components such as capacitor, resistor, diode etc. Okay I believe what it's trying to tell me is that I work with the basic components first and I solder the... I put the components on this side and solder the back. Wow. Welding IC socket, terminal blocks, finally power socket, adjustable potentiometer. The back with the diagonal cutting pliers to cut short the pins as far as possible. Okay well what have we got in the way of components? Got a pile of discrete stuff, some chips. This thing is based around a 2206 CP. I thought this was a pick actually but it's not with a socket. We've got some knobs, a few discrete components. Yeah nothing particularly exotic there. And yeah on this side we have the list of components and an annotated diagram telling you where they go. In fact what we've got here is just a copy of the silkscreen layer on the board. So everything is labeled on the board which is nice. Looking at the components they're not all the same. These are three identical resistors. Right that is in fact the same resistor. No is it? No it's not. This one is brown black brown. This is brown brown black brown. Okay we've got capacitors which are luckily all labeled. Yeah good. Okay this looks relatively straightforward. The components are welding the front board from low to high principles, namely the first low welding components such as capacitors to die etc. Okay so let's have a look at these resistors. According to the schematic we have adjustable resistors. These will be these. B503, B104. Yeah these are the knobs which you control the signal generator with and they go roughly here. Let's deal with them for a bit. We have a 1k resistor, 3 5.1k's and a 330. Ah there's the other resistor. This is a brown black black gold. This is a brown brown black black. Now I did used to know the resistor color code scheme but I'm not going to bother. I'm going to use this component tester. It is a 1k resistor. So that is R1. That seems like a good place to start. Where is R1? R2, R5, R3, 6, 7, 8, R1. So this goes here and how does that look? Not my worst joint. Excellent. The other loose resistor is the 330k which is R4 which is this one. Double check. Yep 330k and that is R4 and that goes next to R1. R4 is here. So I'm sure I'll actually just move my T over here so that I don't move the soldering iron over it every time I take it out otherwise I will get solder in my T which will probably not improve the flavor. Okay now we just need to see the other three resistors. So the back story behind this, let me actually just double check the resistance, is I was working on the flux engine and I was having some difficulty 5.1k good with the clock rate and I was worried that the clock in the microcontroller board, the flux engine is based around was wrong because it's based on an RC oscillator internally and they're not very good. It's supposed to lock onto the USB signal but I was worried it wasn't actually working and I didn't have anything to actually measure a frequency with so I ordered the frequency generator, this one and so frequency measure and you know I thought I might as well get the signal generator as well so that I had something to try it on. Plus it's a useful tool to have and they arrived the other day from warehouse in the UK so they was delivered to our market quickly. So I don't actually need them anymore for the flux engine, the problem I was trying to debug turned out to be a one line, that's not very straight, a one line bug in my code, I was just measuring the time of an event incorrectly. It is interesting that this thing is a double sided PCB given all the components go on one side, I just thought they'd save some money there. The pads are, ouch it's warm, the pads are small but they do seem to solder reasonably well, that might be why it's double sided actually, the inside of all these holes are plated, they're wires, so it may be that they did that to make, let them use smaller pads but still have the solder stick. So what I'm doing here is just attempting to fix that, that didn't really work very well, it'll do. Now there's R5 and R3, R6 is the last one, R6 is, there, so this goes here. I am currently using a new microphone which is a proper lapel microphone, so I don't have the big studio mic hovering above me, this should make me easier to hear, we'll see, I'll see what it's like in editing, which is now clipped to my shirt. That was actually an advantage of being stuck working from home because I was able to, it's actually my work microphone so they are paying, which is nice. Okay that would be all the resistors, what's next capacitors, let's go with the small ones, these are all different, we've got a 473, a 105, a 222, 104 and a 101, non-polar capacitors. Okay C2 is the 104, which one was that, this one. C2 goes, right that's going to be a little bit awkward to solder, so if I push the legs out a bit, yeah that ain't going to go straight unless I can prop it up on something, a miniscule vise, so I should be able to put the cap in like that, do the vise up, yep that holds it in line. These are non-polar capacitors so it doesn't matter which way around they go, oops, which is nice. Okay C2, 104, double check it was, yes it was, C5, 105, 101, this one, there, lamp is in the vise, try and get it relatively straight. Okay double check that, C5, 105, yep, next one is 473, she's C6, okay that's certainly more awkward, that's the one next to C5, which means I cannot use the vise to hold the component in place, so this one, I'm just going to have to wing it, this is not going to be a very straight cap, it's got a good joint, it should be okay and I can't quite read the label but it's something 73 which matches the label here, C6, C7 is 222, not that one, that one, 222 and again it's just going to have to be winged, well that's still reasonably straight, so I have seen people with interesting PCB holders with two little clamps and a swivel, so you clamp the PCB on a mount and you can rotate it, you should get one of those, they look useful and the last one is 101 which goes in C8 which is the top one, okay all right what else we got, we've got the electrolytics which as the manual says the positive long feet, so what that's trying to tell me is there's one long wire and one short wire and the long one is the positive side, these do need to be placed the right way around, the can also has a big white stripe with minus on it to indicate which is the negative side, that's all we got here, this is a 10 micro farad which means one of these, C3 or C4, C3 goes here and it has not actually told me which is the positive or negative side, the indicator is striped, I believe that the striped side represents the negative, they should have printed a plus or a minus next to the relevant leg, so I believe this goes this way around, I should find a way to double check that, yeah if you look at the, this is where the power jack goes, this connector is connected to the, wait a minute what is the earth is that doing, so this is the ground plane and it is connected via this hole to this track which goes to the striped side, that's a very odd way to do it, I mean there's no need for this to be an actual track, it's just a continuation of the ground plane, so also I figured out why it's a double sided board, they don't care about the components, they care about the tracks, right so the striped side is connected to the ground plane which must mean the negative side, this one here is the positive connector from the power which should be connected to that hole there and there it is, so yes, striped means negative, although it is possible it's a center negative jack and instead of having a ground plane there is in fact a positive voltage plane but that would be really weird so I'm just going to pretend that's not going to happen, C3 10 microfarad, this should be the other 10 microfarad cap, yes and this is C4 so this goes there, short foot on the striped side, okay not very straight, one other cap which is C1 which is should be 100 microfarad, yes it is and that goes here, I don't know what the chip this thing has in it is, it could be a fixed function signal generator, I was expecting a microprocessor to be honest and the other one does have a pick in it, right so what have we got in the way of components, we've got the power jack, we've got the there should be two pots, that's a pot, that's a pot, that's a pot, I thought it was two pots and a switch, no three adjustable resistance, okay so you can change the signal, you can change the waveform and I thought one of the pots would do it, one of the knobs rather via a switch but I believe that happens through these jumpers, yeah these two jumpers it says triangle and sign, I don't know what you what you get if they're both connected, probably square wave, let's do that power jack, this is a big component, let's use the vice for this one, trying to keep it level is going to be interesting, see I really need three hands, I need one hand to hold the board, one hand for the soldering iron and one hand for the solder, let's try this, actually I'm going to cut these wires off because they're getting in the way because this is probably going to be the point where I discover that I made a mistake, I have to remove one of the components and now the wires are too short to re-solder them, also I have wires pinging all over the workbench, okay that's better, so we prop the solder up, okay good, it's not very well soldered on but it will now hold the component in place while I do the other joints and then I can go back and redo that first joint, it's a big chunky bit of metal so it needs lots of heat, quite a lot of solder, this one it's not straight, I believe it's too late to do anything about that now, I'm not going to be able to meaningfully desolder this, never mind like so, all right what's next, I think I need to do this, this is a jumper block, why is this a jumper block, what is this for, it's obviously this component, it's not labeled, two by five piece jumper cap, yeah that is this, J3, J3, no, okay this is the chip, yes this is a dedicated signal generator chip, this must be the jumper block here except this is labeled as four by two but this is five by two, I can see it connected to the four capacitors and the diagram, five capacitors in the diagram, C7 and C8 connected together, they're not, I do not think this circuit diagram matches the board, I have no idea what this is for but let's solder it on anyway, this is going to suffer from much the same problem as the this connector, that I have to somehow hold it in place while soldering, I should have put this on before the DC jack to be honest, so if I just do this I should be able to get solder on one joint, okay so that will hold it in place, is that upright, yes it is, yeah it's more upright than the capacitors, that's good enough, so now we do the others, this is old fashioned leaded soldered, it's so much easier to work with than the modern lead free solder, I have heard you cannot actually get this anymore in Switzerland so maybe I can order some black market stuff from Britain, okay what's next, we only actually have a few more components, we've got the the chip or the chip socket which goes in here and they have supplied the cheapest and nastiest socket possible but then I wasn't really expecting a rolled pin socket for a kit costing ten dollars, I'm going to have to use this trick, we bridged that, okay let's just solder on one of these over the other side to hold the thing in place and okay good, lots of magic smoke being released, that wasn't so great but it does seem to have worked, right yes and I even managed to get the notch the right way around, so the chip will then push on to the socket but I won't do that now, next one these jumper, this jumper block, same thing as before, yeah this is actually a little bit more awkward, I should have something to help somewhere, right tape, this is actually how you're supposed to do the other component because that will provide just enough force to let me solder on a joint and then the solder will hold the rest of it and these will then control the thing by pushing on here somehow, wait a minute, I think one of these goes on here and then you adjust something by moving the jumper because the S, I think you adjust the capacitance by connecting which, by changing which capacitor is connected to this wire to the chip, it's going to be interesting to play with and see what happens, okay this is the terminal block that is the output, that will go on here, so we need the tape again, okay it seems to have worked and the only components we have now are the pots, it wasn't on straight, they've made these holes quite wide that's why the components like this aren't going on particularly straight, apart from general you know incompetence on my side, the board is not nearly as nasty as I was afraid it was going to be, some of these kickboards can be really noxious, B104 is R8 which is this one that wedges in fairly robustly, these are anchoring pins and they are really big and it's going to take a lot of heat and solder to get those on, so let's just do the signal pins first, I think I'm also not going to fill the entire hole with solder, no that's not too bad, okay but it does take quite a lot of solder to fill, of course it says fine is R7 which is B503 this one and this one is B, this is also B503, yes there are two of those, yeah B104 this one goes in course and the other two are the same, all right bending the anchor a little to make it grip a bit more firmly, still not very firm, okay that's one leg, let's now we check to make sure it is straight and level before doing any of the others, yeah that's okay because you can adjust after one joint you can adjust things after two you can't, okay all right not doing well with the old clumsiness thing at the moment and the other joint, the other one is this, I believe this is the last component, okay so there we have the board, so let us install the chip make sure the notch goes to the top to match the notch in the socket and more importantly the notch in the label straight in the legs, now the plug's in there, okay so we're done with the soldering so just turn the soldering off for a bit and now we get to build the case and this is a really common laser cut acrylic case, now just notice that it does actually have the controls etched into the top, so we need to peel the paper off and what it will, the way it will work is the these bits will fit into the notches and then the whole thing will bolt together, these acrylic cases are really common, I have a couple of raspberry pi cases the same way and there's a few bits of cheap test equipment, they're kind of ubiquitous, they're not brilliant but they work well enough, okay yeah this looking at the case the jumpers are labeled in frequency bands so that will tell the signal generator roughly which frequency band you want and then use the fine and coarse knobs to control the precise frequency which is reasonable enough, it'd be nice to have actual switches on it but it costs ten dollars, so this yep and the holes match up the PCB so the bolts will go right through, now I can't help noticing that I didn't seem to come with any kind of power connector, the other one came with a usb cable with a barrel connector on the end, so we've got two of these, these will go here, so these have notches out of them, one will be for the power connector and the other will be for the outputs, so this is probably the yep and this one exciting viewing me peeling paper, anyway this is the last one so and this will probably go here, yeah that looks really shoddy actually but that seems to be it, there are no actual instructions for this, oh there's a manual using the step, j1 jumper cap plug-in sin tri blue terminals output sine wave, note j1 j2 can only insert one of, yeah that's reasonable enough, so there's no instructions for the case but I'm guessing that the long bolts hold the uh the top and bottom together while the short bolts go through here and hold the board onto the bottom plate, how many bolts do we have two three four five we've got four short ones, we've got five short ones and four long ones really five nuts, we appear to be short changed but why do we have five of the short bolts given that there are eight holes, you see it doesn't even make sense that they gave us one of the short bolts instead of a nut, this is just wrong, oh well I think I've got some of these somewhere, that doesn't work, the space these nuts are too, these bolts are too short to go through the board and the bottom plate and it's not that I've cut the components off too short because it's the it's the big lugs on the power connector and the um and the pots that are causing the problem, so yeah it's just too small, hmm wonder I might be able to chop some of these off, I should add that the kit I bought came in variety of different versions, these things are completely ubiquitous, lots of people sell them and quite obviously the case is produced by different company than the board itself so I'm not really surprised it doesn't fit very well, that's helped but not enough, I think I might be able to get a bit more clearance by taking these off, more of this one, yeah this is not good and also I want to put the bolts through this way around so the heads are on the bottom, yeah that's not working that one goes in, it is this tab here that's causing the problems okay so if you chew off some of that and yeah that's better, I believe I am flexing the board rather to make this fit but okay that's terrible I really don't want to have to do that the board is distorted, it shouldn't be enough to matter but that's just really bad but let's try the top, ooh now this one won't go in because there's not enough clearance between the here for the power socket, oh there we go it just needs force and pushing so this bit goes on here and plugs into the, wait okay this goes together like this and these bolts don't go through because these holes here have these asterisk shaped inserts for some reason, now the bolts go through but not all the way, I know how this is supposed to work right I've screwed that up, the bolts are supposed to go in like this and then those asterisk shaped inserts are supposed to take the thread so you do the bolts up and they self tap into the plastic that is awful that's a terrible terrible way to do it unfortunately I've now broken a lot of the plastic away but there is enough left for them to sort of work that's why they didn't give me eight nuts because the nuts are supposed to go only on the bolts that hold the the board on, wow well that is it assembled so we put one of these on here and one of these on here and these go on here just turn all these down to zero like so hmm and the next thing to do is to get some power and hook it up to my scope and see where it works so I'll go and set that up now so here it is plugged into my archaic oscilloscope well not plugged in yet but I'll do that just now everything should be set up apologies for any screen glare on the oscilloscope it's incredibly hard to film so we hook this up to one of these wires and nothing happens interesting something should have happened do I have this set correctly DC channel one is not triggering just fiddling with the oscilloscope controls interesting set to sine waves we should be getting a sine wave out of this it's not doing anything that's just mains hum from me touching the contact okay debug time do we have power that's always the first thing to try why am I seeing 12 volts out of this this is connected to usb 5 volts intriguing okay well what could I have done wrong I wonder uh okay well let's take this thing apart again so I can get access to the board this case is a pretty much a dead loss I mean I can't even just use bigger bolts because of the size of the side pieces okay but anyway we here we have this these wires back in these are just cut off bits of resistor leg connect this to power connect this to ground and see what there is to see right well that's got power on it that's five volts you can see two volts per graduation that's a thing that's a thing so the chip thinks it's doing something uh let's stick it on one of these I'm running out of hands I need to yeah stick it on one of these and twiddle a few knobs if I can get this to trigger now that looks like a fixed voltage to me the manual does have debugging steps pay attention to the direction of the ic insert the might damage the chip yes check the ic whether against such as anti please timely correction who knows what that means insert the power supply power supply for 5.5 times 2.1 port center positive barrel negative yep for 9 to 12 volt power supply voltage supply more than 12 volt the power out the output waveform is unstable and here's the pin out of the chip so we've got here is the output and so pin 11 pins yeah pins 11 and 2 should contain the waveform all right well pin 2 is this one there's nothing there just checking the okay that's a zero mode looking at all the numerous controls in the oscilloscope I would expect the caps to be doing something so let's hook that on here there's a thing that it seems to be a fixed uh probably want the other side for that now that's that's a cap doing cap things it is doing complete sod all vcc is pin four to the chip so let's just see if it's getting power one two three four this one five volts so the chip thinks it's doing something well the chip is thinks he's getting power is the chip fried do I have a dry joint somewhere that could be extremely likely uh somewhere there should be an oscillator so fine and coarse here are the r7 and r8 that's these so this voltage r6 r7 and r8 why are these connected in a row the tr1 is pin 7 that should indicate the that should control the frequency so I can see it going up and down as I twiddle the knob oops that's changing a little do I have any caps backwards I'm just looking at the electrolytics here don't believe so I mean they'll all look the right way around I double checked everything so that I don't believe that anything's connected up in the wrong place it could be a dry joint I suppose and well just wondering how best to test this we know it's getting power so that is power we know that works pin one is ground we know that works let's try this one we know that works this one should be connected to pin two sorry this one should be connected to pin two yep uh this middle one is connected to one end of r1 just here yep the other end of r1 is connected to power as you know is on pin four yep this should also be connected to sync o which is pin 11 so one two three four five six seven eight nine ten eleven yep uh let's put this here so that it shows up on camera eight nine ten pin ten should be connected to one end of c3 it'll be this one that's that one pin three this yep the other end of c3 is connected to ground well yeah it's on the ground plane so that's this one is ground yep got a potential divider here r2 on it this is the amplitude this is r2 so one end the middle of r2 should be connected to pin three other end of the potential divider I don't see anything particularly obviously wrong bridge joints no that doesn't look so hot but I beep that one out and I know it works so is it the chip is it subject to has it been static fried so the amplitude went into pin three so connect that to ground so on the scope we see something oh it doesn't move very far does it it's a bit more than that I wonder if I put the pots on the right in the right place what do we get as to one end of the potential divider so this is one end of the 50k pot that's about two and a bit volts I think I melt this end actually yeah that's this one that is two and a bit volts 5.1 k 5.1 k so that should be 2.5 volts and halfway in between so yeah that seems fine I can see that the the wiper and one end of the pot are connected together which is just the same as the circuit diagram so let's just try measuring the overall resistance between the two ends of that pot that's three mega ohms that's at one end let's turn it all the way around to the other four mega ohms interesting what are the other pots four meg let's turn them all the way that way four meg okay to turn them all the way the other way I don't really understand what's going on there these pots seem to be producing completely ridiculous values so we've got 250k and 100k it should be reading a much lower resistance than what the meter is showing so that's actually working this should show that should be registering zero okay yeah um this switch wasn't all the way in the right position let's do that one again shall we right this is more what I expect so the pot is an all the way in one direction which means no resistance yeah turn them all the way in the other direction 100k 50k 50k so this is the 100k which is c1 no it's not 50k which is r7 r8 is 100k this one okay right I got the pots in the right place so the scope is in fact showing no activity from the chip at all the various voltages are doing their thing so c3 looks like it should be some kind of oscillator there's a capacitor on it but then all this stuff should as well let's try pin six one two three four five six this one so that's just mains noise nope I think let's try that again with it plugged in that will always help okay that is showing voltage now but no activity let's pull the jumper no I'm actually a little bit suspicious of the oscilloscope so this is the test path the test point which produces a square wave so yep okay that's all working that's four volts dead on so I would expect to be seeing something from the capacitor bank because I'd expect to see the capacitors charge up and discharge as they do something so okay suspicious of the jumper this says that one side of the jumper is connected to pin five which is tc1 so one two three four five well the other end is connected to tc2 via the capacitor but there's pin six it is looking very suspiciously as if there may be something wrong with the chip I mean I can't see anything else it could be it could be static fried it could just not be a real chip I will test that so what we do is we take some IPA in a cotton bud and we wipe the top of the chip I might actually need acetone for this I think so if it's a fake chip then frequently it will you'll get black and it's not it's completely clean yeah I'll be really surprised if that was fake but yeah and the writing remains nice and sharp yes I am stuffed I have no idea what could be wrong with this I am out of ideas I will have to go hmm have to go and do some online research and see what could be wrong oh well so problem solved it turns out that in fact after doing a bit of research online the device does not run at five volts the manual is wrong or at least incomprehensible uh insert the power supply power supply for five point five times two point one port uh yeah so I have my bench power supply producing eight volts and it actually likes a bit more than nine so let's stick this up to about nine and a half and here we have a sine wave or at least what it thinks is a sine wave it's not really a very good waveform if I change this to triangle you can see it's clipped but I can turn the amplitude down they get a reasonable triangle wave this is at the lowest second lowest frequency so let's put this up to about here and this is not bad you can adjust the frequency fine and coarse they are both actually about the same amount it's back to sine see how that works there's a little better and you notice that we're only getting about plus or minus one volt oh and if I set this to dc uh the everything is floating at about plus five volts but in most situations you're going to be wanting a uh you're going to be decoupling it anyway it would actually be very easy to stick a capacitor in to decouple the supply uh okay let's undo this let's have a look at square wave it appears the way the thing works is it actually generates the square wave and uh then generates the sine or sawtooth wave from that interesting about the square wave is that the amplitude pot does nothing but you can still adjust the frequency and it's okay it's got nice sharp ups and downs let's try it at really high frequency the highest it will go and that hasn't actually gone in the hole okay and let's crank up the time base yeah yeah um two microseconds per division is four that says eight microseconds per oscillation and I can't do that maths in my head but that will give you an idea as to what the frequency is um let's try the sine wave that's a decent sine wave the however the sawtooth is extremely not decent but you have to again reduce the amplitude I have a bit of a feeling that the way it does the sine wave is to just smooth the sawtooth but yeah the shape's okay hook it up to a speaker and you'd get like nasty noises frequency goes up voltage goes down but this is a really high frequency so yeah it does seem to work not running at five volts is slightly more interesting than I was expecting uh also I figured out the case I mean yes I have broken the uh the mount but it turns out that the bolts for the PCB it actually goes together like this so they don't go through the bottom acrylic layer all it does is these bolts together and then where did I actually put the there it is and then this sits like this all the bolts are for is for uh is to uh to keep it in place so we then put these in that one goes in there that one goes there and everything fits together rather better like so some of these bolts would would still do up that is not one of them unfortunately um I can bodge this back together by simply sticking some glue in the bolt holes that will give the thread something to stick on something to attach to yeah anyway that fits together like this the uh and then the top lid that the the PCB is then held fairly rigidly in place just by the geometry of the thing and the pots go on over the top so and there we have yeah those bolts have not worked and there we have a perfectly functional function generator with hair in it well that took rather more debugging than I was expecting luckily it turned out to be something so trivially simple so I'm not going to build the other one now I think I'm going to do that as a separate video because I need to go out and get some exercise stuck in the house all day anyway general comments on the thing the electronics are fine the case is poor the instructions are not good the quality of the actual waveform you get out is exactly what you would expect for something costing ten dollars I can think of a few improvements to make such as ripping out these caps and putting in a proper variable capacitor you know actual switches rather than jumpers but yeah on the whole it seems to work which is just what I wanted so there you go I hope you enjoyed this video please let me know what you think in the comments