So what do you do when you need a modern transistor curve tracer? - Page 1
Forum section: electronics / testgear

author: slow_rider
author_rank: Regular Contributor
timestamp: May 05, 2022, 06:08:12 pm
content: I'll start with this - The option of buying something used from the olden days is out of the questionModern approach seems to buy source-meter (or a couple) and setup everything in software.Is there a modern equivalent for a standalone curve tracer that could be used reliably with trusted calibration and easy export of data?Thanks!

author: Grandchuck
author_rank: Super Contributor
timestamp: May 05, 2022, 08:09:21 pm
content: This one is only low power. It is very useful, otherwise, and stores data in a text file.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 05, 2022, 08:18:44 pm
content: Buy a SMU.

author: slow_rider
author_rank: Regular Contributor
timestamp: May 05, 2022, 08:30:15 pm
content: Quote from: RoGeorge on May 05, 2022, 08:18:44 pmSo this is one approach... Keithley offers several but 2 channels max, so you need 2. Also, tracing of 3 terminal devices and is not built in. They want you to pay even more for a software that does that. A setup like could easily go for $8k+ and you have the complexity of running two SMUs for this 1 task.No one makes new curves tracers professionally anymore?

author: bob91343
author_rank: Super Contributor
timestamp: May 05, 2022, 08:38:44 pm
content: I have been wanting to build one for some time. My first need is for a staircase generator. I would think some ARBs could do this. The second part is a triangle wave generator; these are common and cheap. Add a couple of resistors and a scope and you have what you want, just not self contained.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 05, 2022, 08:41:05 pm
content: Quote from: slow_rider on May 05, 2022, 08:30:15 pmA SMU channel can set either a constant I or a constant V, while measuring both V and I generated. 2 channels should be enough for 3 terminal devices.What for do you need the curve tracer, and what is the budget?

author: Johnny10
author_rank: Frequent Contributor
timestamp: May 05, 2022, 08:45:56 pm
content: Don't forget the B&K 501A Curve tracer you can get for a couple hundred dollars.It's fairly modern.Quite easy to use, you just need a X-Y capable oscilloscope.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 05, 2022, 09:22:33 pm
content: Easy to improvise, too. For power transistors, I made once a Python script and used two channels from Rigol DP832, a lab power supply:https://www.eevblog.com/forum/testgear/rigol-dp832-power-supply-as-automated-curve-tracer/Some other time I've used a signal generator, a scrapped transformer and a DS1054Z oscilloscope in XY mode to identify what type of photodetectors was in a former optical punched card reader from around 1975. It was a phototransistor, not photodiode, not photoresistor.At certain light level + sweep frequency combination, the traced curve was looking like an alligator.

author: dorkshoei
author_rank: Frequent Contributor
timestamp: May 05, 2022, 09:44:15 pm
content: Quote from: RoGeorge on May 05, 2022, 09:22:33 pmPretty common concept, here is similar from Keysight:

author: alm
author_rank: Super Contributor
timestamp: May 05, 2022, 10:38:50 pm
content: Quote from: slow_rider on May 05, 2022, 08:30:15 pmSure they do, it's called a semiconductor parameter analyzer, and it's basically a number of SMUs in a box with some software. TheKeithley 4200A-SCSis one example. They started replacing the curve tracers in the eighties, with units like theHP 4142B. If you think that's expensive, start calculating the price of the Tek 575 in today's money.You can also improvise with power supplies, but you'll often run into limitations like not going low enough in current programming or readback for the base current (for a BJT), inability to sink current, or the ability to sweep from positive to negative voltages. A SMU is basically a power supply that addresses all of these issues. It's just that they are quite a bit more expensive because they are a much more niche item and more much more complicated to design.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 05, 2022, 11:27:54 pm
content: For a very cheap SMU, about $100 yet dual channel and still 16 bits of resolution (though only 200mA, and only 5V), there is the didactic board Adalm1000 from Analog Devices:https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/adalm1000.html

author: Thomas
author_rank: Regular Contributor
timestamp: May 06, 2022, 10:28:53 am
content: Analog Discovery 2 can be used for this too, albeit with a few external components:https://www.instructables.com/Semiconductor-Curve-Tracer-With-the-Analog-Discove/

author: Grandchuck
author_rank: Super Contributor
timestamp: May 09, 2022, 04:17:53 pm
content: Does anyone know about this one?https://www.amazon.com/Circuit-specialists-Transistor-Equipment-Amplification/dp/B084WWY39D/ref=sr_1_6?adgrpid=1338106221000487&hvadid=83631710731906&hvbmt=be&hvdev=c&hvlocphy=71733&hvnetw=o&hvqmt=e&hvtargid=kwd-83631993407050%3Aloc-190&hydadcr=1772_10564911&keywords=transistor+curve+tracer&qid=1652112966&sr=8-6

author: alm
author_rank: Super Contributor
timestamp: May 10, 2022, 07:25:27 am
content: Quote from: Thomas on May 06, 2022, 10:28:53 amThere's also theofficial Digilent solutionandthis third-party solution that pre-dates the Digilent one. But I wouldn't consider the Analog Discovery, particularly with an add-on board, as a professional tool with "trusted calibration". I think it would be hard to find a calibration lab willing to certify this setup.

author: Thomas
author_rank: Regular Contributor
timestamp: May 10, 2022, 10:51:56 am
content: Oops, I missed the "trusted calibration" part

author: Swake
author_rank: Frequent Contributor
timestamp: February 19, 2023, 01:03:50 pm
content: Ok, it is not having the 'trusted calibration' stamp, but for lots of people, me included, the technique from that instructable will do the job. Thanks for bringing it up.

author: jonpaul
author_rank: Super Contributor
timestamp: February 19, 2023, 01:46:37 pm
content: Friends in 15ème found a vintage Heathkit curve tracer 1970s..1980s, cheap. $50!Working fine after cleanup.Heath made 1000s..see ebayJon

author: mawyatt
author_rank: Super Contributor
timestamp: February 19, 2023, 02:28:35 pm
content: Here's one in a pinch, certainly not a stand alone type, nor lab grade precision. Accuracy would be determined mostly by the DSO channels, as 1% resistors for current sense are common.https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/Best,

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 19, 2023, 08:54:00 pm
content: I have a B&K 501.Works fine with an analog scopeA real problem to see traces on digital scope.It is not a modern unitbut very useful and has two channelsOP said he did not want old stuff.

author: David Aurora
author_rank: Frequent Contributor
timestamp: February 19, 2023, 10:16:35 pm
content: There are current model curve tracers out there but it depends what kind of voltages and currents you want to test the DUT at, as well as the volume of parts you want to test. Also, as far as the trusted calibration thing, do you mean you need the unit certified or YOU just need to trust that its accurate?

author: dobsonr741
author_rank: Frequent Contributor
timestamp: February 19, 2023, 10:20:13 pm
content: Why would one want to use a curve tracer in 2023?

author: PartialDischarge
author_rank: Super Contributor
timestamp: February 19, 2023, 10:25:10 pm
content: Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmBecause analog electronics is still relevant and every idiot can count to one

author: TimFox
author_rank: Super Contributor
timestamp: February 19, 2023, 10:26:24 pm
content: Quote from: Grandchuck on May 09, 2022, 04:17:53 pmOut of stock at Circuit Specialists, expected delivery April 2023.I hope it works better than the English translation of the specifications and features on the Circuit Specialists website.

author: switchabl
author_rank: Frequent Contributor
timestamp: February 19, 2023, 10:31:53 pm
content: Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmFor characterising semiconductor materials and processes (and parts). Specialized stand-alone devices still exist (like the Keysight B1500A) but getting a few SMUs may be cheaper and more versatile depending on what exactly you are doing.

author: edavid
author_rank: Super Contributor
timestamp: February 19, 2023, 10:39:02 pm
content: Quote from: Grandchuck on May 09, 2022, 04:17:53 pmHere's a fairly comprehensive review of the CSI4810A/CA-4810A curve tracer:https://www.angelfire.com/electronic/funwithtubes/curve_tracer.htmlUnfortunately for OP, even if this were still available, it's a completely analog unit with no storage or interface.Here's the manual:http://www.madelltech.com/curvetracer.pdfQuote from: David Aurora on February 19, 2023, 10:16:35 pmThat's a bold statement. Can you name even one that is a standalone unit, not an SMU? (I don't think the above mentioned Keysight B1500A counts, since it's an SMU system in a box, and I also think OP doesn't want to spend $86K+.)

author: switchabl
author_rank: Frequent Contributor
timestamp: February 19, 2023, 10:51:35 pm
content: Quote from: edavid on February 19, 2023, 10:39:02 pmOff the top of my head: Keysight B1500A, Keithley 4200A-SCS, several Iwatsu models. Yes they do a lot more than just I/V curves these days and they are not cheap. But neither was a Tek 370.

author: alm
author_rank: Super Contributor
timestamp: February 19, 2023, 11:00:06 pm
content: Quote from: edavid on February 19, 2023, 10:39:02 pmWhy is a system consisting of a number of SMUs in a box that can trace curves not a curve tracer? The traditional Tek 576 etc also had voltage/current sources and voltage / ammeters (on the CRT).Quote from: edavid on February 19, 2023, 10:39:02 pmUnfortunately the OP was last active in July, 2022, so we'll probably never know.This companyclaims to sell the Keithley equivalent for less than half. But if you want something that a cal lab will certify, then I think it's either this or a stack of SMUs, and I'm not sure the latter will be all that much cheaper, especially if you factor in software (buying or developing it yourself).

author: edavid
author_rank: Super Contributor
timestamp: February 20, 2023, 12:18:29 am
content: Quote from: alm on February 19, 2023, 11:00:06 pmI don't have a good answer, except maybe the time required to set up a simple measurement?QuoteWhoops!QuoteThat's $34K for just the mainframe, so it does add up once you add the SMUs

author: alm
author_rank: Super Contributor
timestamp: February 20, 2023, 12:47:23 am
content: Quote from: edavid on February 20, 2023, 12:18:29 amWell, my hobby budget is also slightly below the $80k mark, so I haven't used these instruments, but I'd expect them to ship with ready made templates for easy IV tracing, BJT tracing, etc. Even the old HP 4145A/B and 4155A could do this fairly easily, although you would have to tell them which channels to use and over what range to sweep. Once set up you could save these settings to disk.I'd even expect the modern Keithley (and probably also Keysight) SMUs to easily do this with their software. Wasn't one of the big selling points for the Keithley 2450/2460 how easily they could be scripted, and how a script could control multiple instruments? But I'm sure they found a way to charge a crazy amount of money for this somehow.Quote from: edavid on February 20, 2023, 12:18:29 amOops, that is pretty useless on its own indeed...

author: Whitefoot
author_rank: Contributor
timestamp: February 20, 2023, 02:13:49 am
content: There is a Taiwan company named K&H that makes a stand-alone curve tracer.I don't know anything about it, including price or availability.https://www.kandh.com.tw/ki-3020d-digitized-semiconductor-curve-tracer-ki-3020d.html

author: David Aurora
author_rank: Frequent Contributor
timestamp: February 20, 2023, 01:00:32 pm
content: Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmI use the shit out of mineQuality control of crucial components is the main thing for me, but I've also used it to pin down weird problems to fake or intermittent devices when nothing else made sense. I use it for matching components, I use it to analyse things like zener diode curves in design, all kinds of stuff. Lately it's saved me a couple times when I needed oddball transistors that you can't get new from reputable sources and found fakes/duds amongst them. Problems you just can't catch on a multimeter or basic transistor checker like breakdown voltages not meeting spec etc. Without a curve tracer it's a game of suck it and see, with a curve tracer you can analyse a couple from a batch and go "Oh... this would have died in a week"

author: David Aurora
author_rank: Frequent Contributor
timestamp: February 20, 2023, 01:11:07 pm
content: Quote from: edavid on February 19, 2023, 10:39:02 pmA bold statement? Umm... did you even try googling it?There are everything from these kitshttps://www.thaikits.com/index.php/measurement-testing-checker/ch-012-transistor-curve-tracer-adapter-xy-oscilloscopes-2-ranges-biasOnline%20Electronic%20Kit%20Store.htmlto these little handheld oneshttps://littlebirdelectronics.com.au/products/atlas-dca-pro-advanced-semiconductor-analyser-with-curve-tracingto add ons for other gear like thishttps://digilent.com/shop/transistor-tester-for-analog-discovery-enables-characteristic-curve-tracing-for-diodes-and-transistors/to computer based solutions like thishttps://www.syscompdesign.com/product/ctr-201/to old style CRT based ones like thishttps://www.alibaba.com/product-detail/MCP-QT4810A-TRANSISTOR-CURVE-TRACER_287713173.html?spm=a2700.galleryofferlist.normal_offer.d_title.29f14c85RyLOVRSo yeah, I can name even one.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: February 20, 2023, 02:19:06 pm
content: Hi,I don't know if anyone has already mentioned the PEAK Atlas DCA75 Pro which can be connected to a PC via USB to turn it into a curve tracer :https://printtec.nl/contents/fr/p3905_PEAK-Atlas-DCA75-Pro-Semiconductor-Analyser.htmlhttps://www.peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.htmlAnyway, should @slow_rider need a more professional gear, maybe asking aTE brookercould fulfill elevated requirements and provide recent stuff.Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmBecause it's the best TE you can use to understand how electronic conponents actually work. Also very useful for matching parts and perform ageing or partial failure analysis. With a high voltage unit, you can easily check electrolytic caps for leakage current.I've got access to a marvellousTEK 576(dated 1970) and often use a basic component tester/semiconductor analyser for repair and troubleshooting purpose. The latter is even more useful than an oscilloscope when reparing gear with severe failure (e.g. SMPS).If your DUT is dead, there's nothing much to play with a scope, but you can try to identify some fried or out-of-specs parts with a component tester/semiconductor analyser.

author: baldurn
author_rank: Regular Contributor
timestamp: February 20, 2023, 09:16:24 pm
content: Why are there no cheap SMU available? It is just a power supply combined with a DC load so it can both source and sink current?I wonder if it would be possible to build DIY style.

author: alm
author_rank: Super Contributor
timestamp: February 20, 2023, 10:35:10 pm
content: I'd say a SMU has the following properties:A four-quadrant source, so it supply positive and negative voltages, and source or sink currents (so any voltage polarity combined with any current polarity). This could probably made using a power supply that can sink and source, which I believe includes the latest GW-Instek series, and also older specialty power supplies like the old HP 663xB or 663xx series or Keithley 2302/3/6/8, and a reversing relay.An accurate measurement function (5.5-6.5 digit), which some bench supplies could do an okay job on.Sweep and measure at a pretty high speed, but that's probably not so important for hobby purposes.Numerous decades of current resolution, since testing semiconductors might span from several amps for collector current down to nAs or pAs of leakage current. I'm not so sure how to get this from a cheap power supply, though the Keithley 230x can go pretty low (with some limitations, read the data sheet/manual).There are some cheap SMUs. The AD ADALM1000 (no relation) is one example. Performance is not amazing, obviously.There have been a couple attempts of open hardware SMUs. I thinkthisis by far the furthest along. TiN (xDevs.com) was planning a project at one point, and Youtuber Marco Reps has/had an OSMU project, but I don't either has gotten anywhere near a finished product.

author: exe
author_rank: Unknown
timestamp: February 20, 2023, 10:42:07 pm
content: Why do you need a "trusted calibration"? Semiconductors drift quite a lot with a slight change in temperature (that's why SMU do pulsed current test). Anyway, how important it really is for *you*? Do you really care about every PPM on your curves? I remember if you design a circuit that depends on particular bjt beta then you are doin' it wrong).As for me, I'm more curious about leakage currents and frequency response.

author: switchabl
author_rank: Frequent Contributor
timestamp: February 20, 2023, 11:40:06 pm
content: Even if your design depends on device matching (or selection for some parameter) you may notstrictlyneed tracable calibration as long as you can indepently verify the performance of the final product in a tracable manner. But you may want it to be safe and to reduce the chance of rejects.If, on the other hand, you aremanufacturingthe BJTs, etc., then you absolutely care. Even more so if you are creating a PDK that others will need to depend on to design complex ASICs. It is true that parameters can change greatly with temperature, and also due to process variation, but that is exactly what you need to characterise. Most people never need to do this, however this is exactly the space that these expensive semiconductor analyzers live in. As for frequency response, they usually come with built-in impedance analysis these days.Lastly, if you are doing research and are planning on publishing your measurements, IMHO you should care as well. Though I know too well that money may well be tighter in that case...

author: Martin72
author_rank: Super Contributor
timestamp: February 20, 2023, 11:53:06 pm
content: Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmWhat should have changed that it no longer requires a Curve Tracer ?I am currently building one based on Arduino.This is first for learning purposes, because the data is not different from most other tracers.Because 12Vdc and a few mA are not really suitable to test transistors/FETs for correctness regarding data sheet.

author: chilternview
author_rank: Frequent Contributor
timestamp: February 21, 2023, 12:29:48 am
content: Quote from: alm on February 20, 2023, 10:35:10 pmA 3.5 digit measurement capability would be enough, that's a 12 bit ADC and in fact what the HP4145 has (e.g. on +/- 2V range measure with 1mV resolution).Then if your display has (say) a 0.1mm minimum pixel size, then you could have a screen of up to 40cm across.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: February 21, 2023, 03:30:10 pm
content: QuoteFew changes: analog building blocks are readily available and cheap as integrated ones with very tight tolerances. Like a voltage controlled amplifier, with accurate logarithmic input. Or true RMS converters. 10x better than discrete parts can ever do.Then in high power you have specialized parts, again with tight tolerances and guaranteed specs. No longer using a vanilla part, then selecting into tighter specs of finding matching pairs like in the 70’s.And there is the safe operating area, more important than the curve itself. How would you measure that with curve tracer?In practical terms, if a discrete curve tracer has a meaningful use in today’s engineering than you’d be able to buy one new.Btw, I’m not discounting semiconductor measurement as a new chip rolls out of the production line or when it’s developed. But that’s not curve tracer, rather a much more complicated semiconductor test equipment, going into measuring dynamic behavior up to the GHz range.Oh, if you are into retro instrumentation, please go for it. I saw a wonderful curve tracer in the mid eighties, a vacuum tube based transistor curve tracer. It was already vintage 40 years ago.

author: chilternview
author_rank: Frequent Contributor
timestamp: February 21, 2023, 06:25:17 pm
content: There is a big difference between simple curve tracers (think Tek 576, which was designed in the 60's) and the semiconductor parameter analysers like the 4145 and subsequent models which are really a collection of SMUs and the ability to sweep and graph the results.The latter can be used for characterising all manner of things from a simple diode to a optocoupler to a complete functional block. They are certainly not commonly used by amateurs, but if you have one it's surprising how often you find yourself powering it up and checking if a device really does what its spec sheet says.And yes you can buy them still, but they are not (and never were) cheap:https://www.keysight.com/gb/en/products/parameter-device-analyzers-curve-tracer.html

author: alm
author_rank: Super Contributor
timestamp: February 21, 2023, 09:00:51 pm
content: Quote from: chilternview on February 21, 2023, 06:25:17 pmNeither where the "simple" curve tracers like the Tek 576 back when they were new.According to TekWiki, the 576 sold for about $17k in 2022 dollars in 1969, and $40k in 2022 dollars in 1990. I highly doubt many hobbyists have them. Now of course both used curve tracers (if you can find a working one) and old used semiconducter parameter analysers like the HP 414x series are within the reach of some hobbyists.

author: Martin72
author_rank: Super Contributor
timestamp: February 21, 2023, 11:21:21 pm
content: This is the point.Tracers are unpopular not because they are no longer needed, but because they are simply expensive.A few years ago, we (the company) had the problem of being taken in by fake goods.BUZ84...A classic that we need again and again for older projects.It turned out that one batch already broke down at about 280V, instead of at 800V, as stated in the data sheet.You can't get that out with a simple diodentest or an Atlas DCA75 or similar with low voltage.For a "simple" (I had to smile earlier) TEK576 with its test voltages up to 1500V, this is not an issue.Unfortunately, we didn't have that, we solved it differently.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: February 22, 2023, 02:00:10 pm
content: Hi Martin72,Quote from: Martin72 on February 21, 2023, 11:21:21 pmFor very basic breakdown voltage test of transistors and diodes (up to 1000VDC), thissmall devicemakes the job. It's handy and lightweight.User manualhere.

author: mbrennwa
author_rank: Newbie
timestamp: February 24, 2023, 07:23:43 pm
content: Looks like I was missing out by not looking at this forum more often. Anyway, here's my curvetracer:https://pypsucurvetrace.readthedocs.ioPyPSUcurvetrace takes a somewhat different approach than most other curve-tracer projects that require some specific hardware / board to work. PyPSUcurvetrace is a software toolbox that controls programmable power supplies to set and read the voltages and currents at the DUT. This means you can make a curve tracer from PSUs that are available off the shelf, and you choose the PSU units that suit your application: small transistors, power transistors, vacuum tubes, etc.The PSUs don't need to be expensive "high end". For example, two RIDEN 6006P units can be had for about $300 or less, and will make for a very decent curve tracer setup!PyPSUcurvetrace also allows controlling the temperature of the DUT during curve tracing. I attached an example of an IRFP150 power FET measured at 30°C, 50°C and 70°C.PyPSUcurvetrace not only allows measurement of the curves, but also has post-processing tools for high-quality curve plotting and to determine the DUT parameters from the raw data files (e.g., bias voltage/current for a given operating point, gain parameter, output conductance). More tools like curve matching/pairing of parts are in the works...

author: pizzigri
author_rank: Regular Contributor
timestamp: November 11, 2024, 06:06:24 am
content: Quote from: Martin72 on February 20, 2023, 11:53:06 pmHello Martin, sorry to resurrect this thread, did you finish the tracer you mentioned? I’m really interested!Franco

author: coppercone2
author_rank: Super Contributor
timestamp: November 11, 2024, 06:25:39 am
content: they are awesome you actually know what is going onI think if you think you don't care it means that your not doing difficult circuits or used to working with serious copypasta engineering / generic clone designsI personally never used one because I was mostly experimenting with op-amps and integrated circuits that are too complex. Now I am starting to get interested in more customized and special circuits (and attempting more difficult equipment repairs) so its a great thing to own.

author: guenthert
author_rank: Frequent Contributor
timestamp: November 11, 2024, 09:16:19 am
content: Quote from: dobsonr741 on February 19, 2023, 10:20:13 pmNo idea, but when the company I worked for moved into flashy new office buildings at Santa Clara square in 2019, ADI became our neighbor. They were a bit slow to move (well, I suppose, moving electronics lab equipment is more cumbersome than some server racks) and for a few weeks I could peak into their lab on ground floor. I saw there an old (seventies?) Tektronix curve tracer and was wondering if they were about to dispose of it and I could score. Then however I saw half a dozen more of those in as many work stations. Clearly, they were still using those, heaven knows what for. I never figured that out as shortly afterwards they frosted the windows at eye level.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 11, 2024, 09:36:29 am
content: Quote from: guenthert on November 11, 2024, 09:16:19 amhttps://duckduckgo.com/?t=ffab&q=periscope&iax=images&ia=images

author: Dbldutch
author_rank: Regular Contributor
timestamp: March 19, 2025, 01:54:39 pm
content: Reviving this thread that I didn't see earlier.We have designed a pretty good CT that has all the required data made available to build one yourself.https://www.paulvdiyblogs.net/2022/06/the-vba-curve-tracer.html