eBay Transistor Curve Tracer Kit - Build,Test and Review

I found this inexpensive transistor curve tracer kit on eBay for about $25, including the power supply (transformer not included). After soldering all the components to the PC Boards, I wired it all up in a home made case and tested it out. It actually works! You just have to be very careful not to connect the transistor incorrectly, or it will fry it pretty fast. Check it out.

[@adamwolfram6126]

I love these "low cost test equipment" videos. For the advanced hobbyist who won't be buying a $1,000 Tek curve tracer, this is helpful. PLUS - you save us time and possibly frustration by pointing out the errors or poor design choices you find. I appreciate it very much! Note: I do believe buying a GOOD 'scope is a must - and a serviced and calibrated Tek 2000 series is certainly affordable. I went from a cheaper scope to a Tek 2336AY, then a 2213A, and the difference in quality is remarkable.

[@richardmarshall6751]

Three (“thu-ree”) , or 3, bloody remarks over the use of the term “‘‘em A” for milliamperes?! Seriously, people? Been working in electronics for 50 years, everyone uses the mnemonic pronunciation; it’s universally understood, faster to say, and utterly professional. Get a life, people. Oh, and btw (“buy da weigh”), thank you, Tony, for taking the time to make this video and sharing your experience and knowledge. Pretty sure that’s what those 3 mA Karens meant to say.

[@ydonl]

Sometimes it's fun to run the numbers. Let's take the 15 volt supply, and place it across the 1k resistor and the 6.2 volt zener in series. So to use up all 15 volts, that means there's 8.8 volts across the 1k resistor, since there's 6.2 volts across the zener (and the circuitry in parallel with it). Since there can only ever be 8.8 volts across the resistor, according to Mr. Ohm there can only ever be 8.8 mA of current through the resistor (8.8 volts / 1000 ohms). That current through the resistor is the same current that flows through the zener and the circuitry as well; these are in parallel, and whatever is not used by the circuitry will end up flowing through the zener. So the worst case for the zener is when the circuitry is using none of it, and all 8.8 mA flows through the zener. So the maximum power in the zener is volts * current, which is 6.2 volts * 8.8 mA, or 0.0546 watts. Tiny. That means the power rating of those zeners shouldn't be a big issue. I could speculate about what other reasons there might be for having the two diodes in parallel, but let's not go there. At least we can see that technically, power handling isn't one of the possible reasons. We'll never know. :) Still, it is nice that there's another pretty easy way to get a pretty reasonable curve tracer for a home lab!

[@Ezric2]

Ive watched this video a few times now that Ive gotten my curve tracer built and working. Excellent teacher and mentor my friend!

[@donaldfilbert4832]

I bought this same kit !! Worked out very well. But then I looked for and found a tester that took functionality to a much higher level - without breaking my wallet. I got a Heathkit IT-1121 Curve Tracer in excellent condition off of e-bay for $90. I can't image needing more functionality that it provides - and at a very reasonable price !!

[@lego40404]

Love it, I’m in the market for one since all I tool around in is analog and tube equipment. I am not schooled in electronics but I’ve been in the hobby over 35 years. I’ve made some something’s, repaired some things and unfortunately made something’s worse😂. In my field of being a HVAC operating engineer I’ve been able to make repairs on boards to get equipment back up and running rather than having to wait for a new board, sometimes I can’t even get a new board on much older equipment. Thanks Tony

[@rogeronslow1498]

The TO-220 F pack is not a cheap plastic device. Its thermal resistance is documented in the datasheet and isn't particularly high and perfectly suitable for its application and power level. The 7805 is also available in a TO-220AB package which is probably what you are more familiar with. The F pack is very desirable for high voltage mosfets when the insulator and insulating bush are unsuitable.

[@paulm3079]

The tektronix 571 (and others) used to ask the user which load resistance was to be used in order to protect the devices as this fella had correctly identified. 570, 571, 575, 576, 577…….

[@SimpleEnough2k9]

I bought one and assembled it yesterday. I did a test on a classic 2N2222 transistor and the trace appeared on my DSO. Despite the fact the trace wasn't as sharp as it would be on an analog scope, I was fairly happy to see some results. However, my happiness somehow went down the drain when I actually measured the traces and did the hfe evaluation as per the docs. Funny enough, I got a trace like the one in the docs for the NPN transistor. The X axis set to 2V/div and the Y axis set to 10mV/div. I calculated an hfe of roughly 330, which I think is fairly high. I then evaluated the hfe with my DCA55 from Peak Atlas, and the reading was around 250, although the base current was around 4.5ma which doesn't really compare to 168uA. On my DMM, I had a value in the 260 range. Obviously the 330 value is pretty much out of bounds but I'm not too sure where to look to determine if something is actually defective. Meantime, I will do other tests on small and power transistors and see if the situation is the same for them. I would be surprised if a resistor would be out of specs because I measured every single one before putting them on the board when assembling it.

[@xraytonyb]

I had a tough time figuring mine out as well. I also have a Peak Atlas. The hfe measured on the Peak Atlas was pretty much in line with the curve tracer once I figured it out. I also can tell you that if you set the tracer to high powered transistor mode, it will fry a 2n2222 or any other small transistor. Getting a good trace in X-Y mode was also difficult at first. I kept getting a lot of weird traces that I am assuming were retrace lines or something. The instructions are poor, at best. The thing that I noticed is that the scale can change, based on the transistor. The instructions indicate that X-Axis is set to 2V/Div, but Y-Axis can be anywhere from 20-100mV/Div. If you don't set it right, It's really easy to count the steps wrong. If you get the wrong step, it will cause you to calculate the hfe incorrectly. I had problems with this at first, but was able to get it to work after some trial and error. Another good use for this device is matching transistors. Closely matched transistors will put up almost identical-looking traces. I was able to match a set of output transistors in short order, once I got everything set up. When matching them, you really don't have to calculate the hfe each time. You just have to match transistors that have similar trace amplitudes. Keep working with it. The more you use it, the more you will see it works pretty good for the low cost. It isn't a Tektronix, but it does what I need it to do. Good luck!

[@InssiAjaton]

About your zener concern: If you have no other load in parallel, the zener passes a whole (15 - 6.2)V/1000 ohm, or 8.8 mA. That again means 54.5 mW or about 1/10 of the rated 1/2 watt. Any other load for this shunt regulator will reduce the power dissipation in the zener further.

[@taintedmeat9740]

I like that chassis you cooked up for this kit....well done !

[@patrick4228]

Enlightening, thank you! For those interested: the transistor curve tracer from this video is still available (March 2023) through Thaikits. I just bought one and am satisfied with it.

[@MrMersh-ts7jl]

where did you purchase it from? also did you purchase the set that came with the power supply? also can you provide which transformer you used? thanks in advance!

[@stevenbliss989]

RE: zeners. Two 1/2 watt Zeners are correct. Just because a zener says 1W it is NOT 1W. Look at the package, there is NO WAY that tiny thing will dissipate 1W, I suugest you do what they said before you 1W's blow up. There are PILE os diodes rated for 3A, and if you did that to them they would blow up near instantly from heat! BTW I love your 2465! :)

[@retrotechandelectronics]

I just finished repairing an IT-1121 that needed a lot of work and is now up and running. Was Heathkits semiconductor curvetracer

[@donaldfilbert4832]

Yes - I saw that on your channel. Great job. I also have one of these I bought on e-bay. Excellent hobbyist level tester !!!

[@stevec5000]

You probably should add an option to switch in a current limiting resistor to protect low power transistors.

[@stevenhardy2898]

I have a Sencore 150 MHz scope SC301 that includes a simple octopus type component tester The nice thing is that one button and its alive. Push the button again and the slope returns to normal use. Wish a digital scope would offer the built in feature. ( I first used one as a bench tech 45 years ago... a great time saver.

[@xraytonyb]

I really like the old Sencore equipment! Thanks for watching!

[@ableutopia2721]

Nice neat and clean layout, good work. Some ideas: Why not get rid of the zeners all together and use LM78/7906 TO-220 regulators? You could also modify that supply circuit to implement on the same regulators a current-limiting capability.One question: In your scope display, what is that 45 degree bold trace across the curve traces?And sure enough, the tracer is really pushing the transistors well into its design limits. Have you tried testing diodes/zeners with it?Thanks for sharing, best regards.

[@mbaker335]

The plastic TO220 cases are the new style and work fine.They are not cheap, just a newer package. By the time you have added heat sink compound and a mica washer then you will get more or less the same performance anyway. I would be happy to use them.

[@rich1051414]

If you need the heat sink isolated, sure. That isn't the case when each transistor has it's own heat sink, isolation isn't required.

[@andymouse]

You make a good point, if your heatsink is not isolated, and you use a piece of Mica, then there's not much difference thermally, in fact, thinking about it the plastic case is probably better, certainly cheaper from a BOM point of view and much easier to mount.

[@donaldchapman8392]

Just one question. Did you tie the chassis of the box to incoming AC ground? The BNC connector shields are at the ground of the +/- 15v supply? Should the center tap of the power supply be at chassis ground?

[@lucienpellerin]

A 1 watt zener diode with it legs cut of is no longuer a 1 watt diode,what you should do is coil both leads of the zener ,then solder it to the board,the full lenght leads are acting as a heat sink,this will prolong the life of your zeners.Some manufacturers will put the mounting holes far apart so you won't cut off those leads wires..Bye.Lucien

[@warplanner8852]

Fun video and _excellent_ replacement part considerations. But, tell the truth now, you just wanted to show off your ultra-boss Keithly, didn't you?

[@jdmccorful]

Thanks Tony, found on ebay along with transformer and purchased.

[@michaelwolak3098]

Hi Tony came across this video and thought this would be a great project whilst shielding my question is what was the transformer that you uses as will have to source one, and I agree with replacing the regulators. Keep up the good work Regards Mike

[@TheBdd4]

Well done video, neat construction, thanks for the upload.

[@williamsquires3070]

Actually, those have metal tabs that are coated in plastic for electrical isolation so you could mount both on the same heat sink without shorting.

[@harveyjones4265]

William Squires ,

[@harveyjones4265]

Williamson Squires w7t

[@henrihoopkins2822]

We have two 15volt regulator to two 6.2volt zener regulators, what a wast of power, and the power transformer has to be 36 VCT@1A. I have bought a kit including the regulators, but I am going to change the power supplies to 12volt regulators and then to 6.2volt zener trgulators. Why not go to 6.2volt regulators or use 6volt regulators which is even more simpler. The power transformer can be 25.2 VCT@1A. If you add a fan with vent holes you can use 85 degree capaciators To me the PS are more complicated then necessary. Since there is no current limit for the transistors I am going to see how Tektronix does.

[@waynec369]

Impeccable panel labeling.

[@scottosds]

You can turn off channel 2 in XY.

[@valakatz3967]

Hello Sir would you be able to share the schematic, I did not get anything with my purchased of this curve tracer. Any help would be appreciated. I want to know the connection for the X and Y axis and the ground point. Thanks! Thanks for sharing nice video.

[@acertech]

Hello. What are the output AC voltage on your transformer? Do you need much over 15V AC?

[@oliverhertwig359]

Geir, I would suggest using an 36V center tapped transformer with at least 80VA. This should give you 2x 18V at 4.4A. 18V is very gentle to the 78xx/79xx regulators and I think the circuit voltage drop won't be too high so that you'll get nice and stable +/- 15V at the output. Search e.g. for 185E36 from Hammond.

[@rpbale]

Another great video! Ever thought about building a curve tracer for tube matching or better yet converting a semiconductor version for tubes? I want to make it my next project. I have a Tektronix 5CT1N curve tracer plugin for my scope that I'd like to adapt to handle power tubes. Don't know where to start yet...

[@xraytonyb]

Rick, Tubes and transistors are different, in that tubes are more of a voltage controlled high-impedance device and transistors are more of a current controlled low impedance device. Because of this, testing them is very different. The best way to match tubes is with a mutual conductance Tube Tester. By measuring the GM of a tube, you can closely compare it to other tubes for matching. Newer testers such as the Amplitrex (big bucks!) can give a full report of the characteristics of a tube. There are also some companies that modify the old military TV-7's or the Higher-end Hickock testers to do the same by using a computer-based interface and software.

[@SODA-iz8lc]

I note your scope was set at ch1@ 2v and ch2@100mV but on the Chine's scope it was set at, ch1@ 2v and ch2@ 20mV. So, how did you calculate ch1 to be 20mA/division or is it always 20mA/div

[@nickking8317]

Might be helpful for my studio build I'll defiantly buy another old dunga cro for one and get a kit plus I'll use another one for my octopus that's a scratch build

[@vandal968]

Anyone know where these can still be bought cheap? Best I found was $37 delivered on eBay and that is without the PSU board.

[@humberto4017]

great video, coul you give me the link where you bought it. please.

[@ulisesaguilar4392]

Good after noon Sir, I ´M checking out Your video Its grate , I want to know if the schamatic of the transistor curve tracer came with it , If can answer back

[@basstard13]

Hey, sorry for the noob question: do you think this is suitable to trace jfet curves? Thanx

[@jameswarren1831]

basstard13 I have the same question.

[@basstard13]

@@jameswarren1831 doesn't look like the guy likes to reply to comments tho...

[@jameswarren1831]

@@basstard13 It's pretty old and I don't think he gets bumped by my reply on your comment. He does give out an email to contact him, maybe give that a shot? I would like the ability to match Jfets.

[@basstard13]

@@jameswarren1831 must have missed the email part, where is it? I'll drop him a line

[@moon1985bc]

do you think you are really a bastard?

[@paul.alarner6410]

have you a link for the kit or website as my searches come up blank.

[@TboneLoyal]

How do you keep the high voltage from main voltage on the scope? I had never heard of this when i was a kid. But it seems its a big deal now. Everyone is scared to hook up a scope to high voltage.

[@johncasteel1780]

"Everyone is scared to hook up a scope to high voltage." No, "everyone" isn't. Some of us just know "how" and "when".

[@cv793]

Can you share electrical diagram in good quality ? For exampe attached to this video .

[@ulisesaguilar4392]

thks for sharing grate video + information

[@pattheitguy]

"mA" = "milli-amps" or "milli-amperes"

[@rodneyjaygarrett]

I was wondering if you could share your specific's on the transformer you are ising. I bought 2 30vct tramsformer rated at 500ma each . I am running them in parallel that should give me 1 amp . My question is shold i be running a higher voltage tramsformer to overcome the drop out voltage of the 7915 and 7815 voltage regulators. I quess my question is , shouldI have a 32vct tramsformer .

[@rodneyjaygarrett]

Thats 2 transformers each at 30vct

[@rodneyjaygarrett]

Thanks boonedock .I will take your advice.

[@redfelipe6565]

Thank you Sir. Like.

[@abeleski]

so which kit is this then?

[@bustersinclair]

good stuff man....subscribed...

[@xraytonyb]

Thanks for the kind words and the sub!

[@anks888]

HI im wondering if you could help me out I've got one of these kits but I've lost the paper work could you by any chance help me out thanks kris

[@xraytonyb]

Send me an email at [e-mail] and I'll try to scan you a copy of what I have. Things are pretty busy at work right now, so it may take a couple days to get it out.

[@Bangkoktoshop]

You can buy from the official website Thaikits.com , below is the link www.thaikits.com/index.php/measurement-testing-checker/ch-012-transistor-curve-tracer-adapter-xy-oscilloscopes-2-ranges-biasOnline%20Electronic%20Kit%20Store.html

[@EdEditz]

You can build your own curve tracer using just 6 transistors. I explain how you can do that here: www.eddybergman.com/2017/06/simple-but-effective-transistor-curve.html

[@BruceNitroxpro]

I love the way you think. Better is better. de KQ2E

[@kwgm8578]

You bought a Chinese kit for $22 that contained Chinese parts, and you're surprised?

[@8-bitbitsa821]

Like the video... BUT please stop with the “M A” stuff ? it’s milli-Amps (mA) ... milli - amps 🤦🏻‍♂️

[@brucewoods9377]

You could have said milli amps instead of em aye. It sound so un professional

[@xraytonyb]

mA is an abbreviated term for milli-amperes. In the X-ray industry (which I have worked for 27 years), it is the common word used to describe x-ray technique (i.e. kV and mA) . It is easier to say, and it is a force of habit for me. If you hear me say "mA" in the future, it means milliamperes. Sorry for the confusion.

[@dannywest749]

Well, I'm not Xray material...so I will move to another channel.