eBay Transistor Curve Tracer Kit - Build,Test and Review

all right here we have a thing I got from eBay and it is a transistor curve tracer and of course if any of you are into electronics and you understand what a semiconductor curve tracer does it allows you to measure and match transistors and semiconductors and to test them now Tektronix corporation the fine purveyor of oscilloscopes also makes are used to make a line of curve tracers and even a used one can be thousands of dollars if you get a good one that works and even to get a broken one that doesn't work and have to repair it which is very difficult can be a thousand dollars or so so this was something I picked up on eBay and not including the little transformer which I got separate this whole thing came to like twenty dollars or so on eBay and it consists of the curve tracer circuit itself which comes like this with these instructions and comes with a little power supply that matches it and you assemble the little kit and it comes with these nice instructions and shows you how to use it how to connect it so if you look here little schematic and of course I'm sure this isn't going to work like a multi-thousand dollar Tektronix but even if it works to the point where we can you know that we can plot out some transistors and match them check their breakpoints and so forth I think this will be a handy little device especially like the last project we just did online the SX 450 pioneer receiver it doesn't have a DC balance adjustment for it and it doesn't even have a bias adjustment so the matching of the transistors in that type of instance would be very important because if you had a set of transistors that were too far mismatched from one another and when they make transistors even though it might be the same part number they're all a little bit different they all have a tolerance so the idea is to find two of them that were manufactured that came out with very very similar performance specs and the only way you can do that is to test it with this type of device so if this works at this cost it would be a great little addition to the test equipment that we have here so I thought for the 20-some dollars it would it costs it would be a fun project to build if nothing else and a nice learning experience so we're going to assemble this and I'll have you walk along with me as I do that I don't have a case to put this in yet but I'm sure we can make something up you don't really need anything fancy for this it's a piece of test equipment so let's just start and see where this ends up so I'm going to get everything out and start putting things together all right taking this out of the bag the first thing I noticed was a couple of things I don't like if you look at this very lightweight voltage regulator these are a seventy eight fifteen and seventy-nine fifteen which is a positive and negative fifteen volt regulators but if you notice they're completely totally made of plastic not very good conductor of heat these are very cheap low-end ones and the funny thing is they actually give you heat sinks but a heat sink is going to do a lot of good with a plastic case like that so I had some new old stock RCA regulators and if you notice they have the traditional metal cases they're rated at the full 15 watt which is 15 volt 1 amp and they're very sturdy very reliable so I feel a lot more comfortable using these parts here then using these old cheap plastic ones so I think that's what we're going to do the other thing I noticed is these are not the world's greatest capacitors they're 85 degrees C they'll probably work for what we're doing they're rated at 35 volts so which is more than double of the 15 volt supply but again I would probably prefer to put a little better quality 2200 which something closer to like this so we have some of those I may have some 35 volt ones yeah I do so there's some 2200 at 35 so I think we're going to use those instead better a little better quality and these are 105 degree rather than 85 degree they'll just last longer again it's a piece of test equipment you want good components nice quiet power supplies and so forth this would probably all work out of the box but you know if you can afford the couple dollars for the better components you're better off doing it up front so this is pretty much everything here so we're going to just dig in and start putting things together okay so we have this all soldered up put together turned out pretty good so I've hooked it up to just a little couple hundred ohm load resistors put it under a load I have the transformer hooked up you can see right there connect two distant leads and we're going to plug it in there's our load resistors here in here and let's plug this in and see what we get so right now I'm hooked up to the positive 15 volts so there's plus 15 and it's 15 point oh and move over to this one minus 15 minus fourteen point nine seven so I would say that would be a success so the power supply is all together and ready to go so all right now on to the main board a little side note on this board a couple extra things I did was I put heat sink compound in insulators on this it didn't come with any insulators because those other ones were plastic which I don't think we're going to hold up as well so I did insulators and heatsink grease and then I was able to they already had the holes drilled for these but they needed to be insulated from the tab on the regulator because the regulator's actually these these tabs are actually live so I screwed found a couple of screws that fit and screwed this in there so it's nice and sturdy the other things that I did was these are 105 degrees Celsius capacitors much you know higher than the one the 85 s that came with it these are 125 degrees Celsius because they're like right up against those heat sinks and I figure if these are going to get warm they're going to warm up these capacitors and that could shorten the lifespan of the caps so having these high temperature ones will really really extend the life of this power supply so I think it'll last a really long time without failing okay little update here I just started putting this together and I noticed there were four of these little run-in with a 52-34 and if one end 52-34 turns out to be a 6.2 Volt half watt in your diode I thought that was kind of strange the way they were going into the board so I looked on a little snag that came with it and found that what they're doing is they're putting two diodes in parallel to here to here and the reason that they do that is to handle a higher current now we're taking 15 volts and we're dropping it down to 6.2 so we're cutting that voltage in half and then you have this 1k resistor here so I think they were afraid of the half watt wouldn't be enough but they didn't want to you know they probably had the half watts available and didn't want to go to a 1 watt so they did that but this is a bad design whenever you put Zener diodes in parallel the dominant diode the one that's got the slightly higher voltage will be dominant and it will or slightly lower voltage I'm sorry it will clamp off all the voltage and the other one won't so really it really doesn't do you any good unless they're perfectly matched and even at that if one of them drifts a little bit or heats a little bit more than the other it'll take over and it defeats the whole purpose so this is a bad design so I rummaged through my things and I found a couple of the proper 1 watt 6.2 volt diodes z nurse and I soldered those in and then I just plugged off the holes for the extra ones in there and I think that's going to be a lot more viable stable circuit than what the way they were doing it so sorry but got a deviate from the design a little bit so just wanted to give you that update and we're going to continue on and start populating all these components okay we have this all put together and I have it all soldered up have the power supply connected to the board just laying on here and what I'm going to look at here is the output when I believe is the output of this generator which is right here and I'm not sure which side of the resistor I want to get on but I'm going to get on this 10 ohm resistor and what we should see right here is some sort of a waveform probably either a sawtooth triangles sine wave something like that and eventually what we're going to do between these two is we're going to make like a stepped wave form out here that's going to cause the patterns so we can look at our transistor characteristics so anyhow let's put this on and see if this thing generates a signal all right so move up to the scope let's see what we get all right plug in and looks like click we're getting eight just a regular triangle waveform there so that's good let's go to the other side of the resistor so what we get same thing there we go that's good so our transistors are working so that's a good sign all right and if I look this is what goes to our scope all right so now I want to take a look at what is being generated on our output that's supposed to go to our semiconductor so let me get figured out here and we'll be right back okay let's see if we can get on this shorten things out and I'm generating a lot of noise here holding a probe on but basically there is the drive signal for the base and you're not seeing it very clearly because it's not locking on to it very well but so we have the drive signal for the base of the device and test if I look at these other ones there's the triangle so between that ramp and the triangle that's what's going to give you your stepped wave fan through the transistor and that to my understanding is what allows the pad of the listed u pattern or whatever you want to call it on your scope the XY pattern so I'm pretty confident this is working so that's good and I have a case that I'm actually starting to put together and I just put some paint I made it out of aluminum and wood just a quick one here's what we're going to do put some food on it and then there's two switches that have to be in there and those two switches go for the where's our jumpers at they actually have a jumper right here J 1 and J 2 those are actually going to be replaced by switches you can see their actual jumpers on the board but we're going to there's actually little terminal strip if you look here or a little holes there eyelets where we can put wires and we're going to run little wires and we're going to put switches so that we can switch between NPN and PNP type transistors that's the first jumper the next one is to switch between low power and high power transistors so the small transistors and power transistors so we're going to put those switches on the front panel we're going to put our X&Y skirt output NC Jack's on the panel we're going to put it on off switch we're going to wire in a little LED for power on indication and then we're going to have our three little banana plugs for your device under test and that way we can plug these little alligator clear these little hook clips and I'm actually going to possibly shrink these wires down a little shorter so they don't create as much noise and that should give us a finished product we can test it out so as soon as we get the case done we'll be back okay I finished wiring this thing up and you can see it turned out pretty good so we have power cord coming in got our transformer mounted fuse holder have the main board here of all the switches wired up you can see there this switch here goes between large transistor and small transistor so when its flipped up it's four power transistors which is what I have connected right now let's see it's a 2 n 3 o5 v NPN and this one here is for NPN and PNP switching got a LED on indicator we have our emitter base collector input wires and our x and y X is on the bottom y is on the top I still have to put the labels on here with my label maker and it's going up to my oscilloscope and the scope is in XY mode now for any of you never heard of XY mode when you turn your seconds per division your time knob all the way so right here time knob all the way to the left if you notice on most oscilloscopes you'll see a little area at the very end called XY okay so you can zoom in on a little bit see what it says XY and what that means is when you apply a voltage so at first you get just a dot in the middle of the screen you can see it there and I'm going to turn that down so it doesn't burn my screen basically putting voltage on this will make the voltage change in the x-axis and putting voltage on this terminal will make the dot deflect in the y-axis so basically you're controlling the position of the dot with those two inputs from on the x and y axis now that's exactly what this is doing by applying basically a staircase signal to the transistor we're able to trigger the transistor to function at different levels now when you're in high power mode let's back off here a little bit when your high powered mode there are eight steps from zero ma all the way up to two point two for M all right each step and when when you see this pattern here each one of these lines represent one of those steps when you're in low-power mode or small transistor mode these are the micro amps that each one of those lines represents okay NPM is going to go up PNP will go down all right so if I turn this on and I turn my intensity up you can see these um these lines here okay starting with zero okay we zoom back in so we start at zero this next line since we're in high-powered mode is 0.32 ma 0.64 ma 0.96 ma 1.28 ma 1.6 ma to up to visit ya 1.9 - ma and 2.2 4 ma okay so basically when we apply that much MA to the base of the transistor okay that's showing us where the knee point is where that transistor is turning on now if we can if we have a known input okay for instance if we take the very last two point two for na when I'm applying two point two for ma across the base okay so that's two point two for ma of base current on the transistor then I can take from my zero point up and measure I'm at 2 volts per division okay and basically with 2 volts per division 2 volts per division according to this is going to be 20 ma per division okay so I go 20 40 60 ma so I have roughly 60 ma is where I'm turning on and I'm turning on with 60 ma I'm turning on or with what 2.24 ma I'm causing 60 ma to flow in the emitter-collector so if I take my take my 60 ma / 2.24 ma the gain of this transistor is twenty six point seven eight five the beta is twenty six point seven eight five that's your forward current gain okay now what I did find is this works really well on large transistors okay like these big power transistors now I tried originally to connect a little 2n 22 22 to this and even in low power mood they get really hot really fast so you can't leave this on for very long that is what I'm starting to see is the fatal flaw in this little design there's no protection for the transistor also it says directly in the instructions even if you hook up the transistor backwards you will burn it up right away so you have to be extraordinarily cautious that you get base emitter and collector connected properly and that you do not turn NPN and PNP backwards because once again that will immediately damage the transistor so this one is just a little bit lukewarm now starting to get warm but so anyways it does work and it works really well I was surprised you just those two those that that caveat you have to really be careful with the connections and with the switch configurations if you do it wrong instantly damage the transit sister other than that this is a very good circuit it seems to work really really well so I'm pretty pleased with it I did make a little top for it just out of plywood you can see here so and I just did a miter joint real quick glued it up rolled some duckstein on it that I had left and it can and I'll put it together and I think this is going to be a good project like I said once again the only thing you got to watch is the wiring of the transistors so I give this thing a thumbs up especially for the price it was $24 and if you look up transistor curve tracer on eBay this little kit will show up and there's two ways you can buy it you can buy it with the power supply module and without the power supply module either way for 25 bucks you get power supply and everything and I think that's a real bargain quality of the parts not too bad I didn't like the fact that these they doubled up on these zena's that was a bad idea so I changed that I went with the little better capacitors because these do get warm these little heat sinks here and I did go one of these BNC connectors was defective so I had to replace that with a good one but other than that it was a really nice little kit the resistors measured spot-on everything was good so I give it a thumbs up and if you liked this video I encourage you to give the video a thumbs up and have a great day thanks a lot for watching more to come

Channel: xraytonyb

Views: 33,339

Rating: 4.8696218 out of 5

Keywords: electronics, vintage electronics, repairs, stereo, restore, restoration, vacuum, tube, amplifier, radio, alignment, calibration

Id: 7exRUNCQ-hI

Length: 25min 24sec (1524 seconds)

Published: Sun Jul 31 2016