433 How Transistor Testers Work and How to Use them?

[@AndreasSpiess]

I am still in my summer break. As last year I show some interesting videos from the past (as mentioned in the intro)

[@doejohn8674]

Enjoy your holidays and thank you for your very didactic videos!

[@BerndFelsche]

This video is worth the curtain call. Component identification is a hot issue with supply chains struggling and people getting dodgy parts, even through their usual, trustworthy suppliers.

[@docwhogr]

damn, youtube now has reruns?! :P i'm waiting for the solar panels cliffhanger to be concluded..

[@paulskaar8556]

I hope my countrymen are treating you well and that you are not too saddle sore or too hot. Cheers from Los Angeles.

[@johnwest7993]

@@doejohn8674, a techie who is fluent in English! A rare breed. :)

[@williamwatson1532]

I remember watching this the first time. It's a great exposition of how these testers work and very well worth repeating. I've enjoyed watching it again. Thank you, Andreas

[@AndreasSpiess]

You are welcome! I thought it is a good candidate for a replay during my Summer Break

[@serggorod1423]

Присоединяюсь к благодарности! Очень быстрое объяснение и при том ничего почти не упущенно. Лучше на канале, даже поставил колокольчик!

[@usefulelectronics]

It is amazing how this tester shows you the component pinout. This can save a lot of time searching for the correct component data sheet. I really like this tool and I need to have one I will order one soon. Thank you for the awesome tutorial!

[@AndreasSpiess]

I think such a device should be in every lab...

[@digihz_data]

Great information about these tester Andreas. Thx.

[@AndreasSpiess]

Glad the video was useful!

[@tookitogo]

At the vocational training center I worked at until recently (outside of Zurich), we have various projects used for soldering and assembly practice for electronics apprentices. One project we introduced recently was the component tester with rotary encoder. We buy the boards as kits and have the apprentices build an enclosure from sheet aluminum according to a drawing designed in-house, then solder the board and install it. Very nice little project!

[@AndreasSpiess]

Indeed a nice project. And very useful!

[@tookitogo]

@@AndreasSpiess Absolutely! I use mine at home regularly, and I know the teacher’s one gets used frequently by the apprentices. :)

[@MeinElektronikHobby]

... Danke für dieses tolle Video. Eine der besten Erklärungen, dich ich zu dem "Transistortester" gesehen habe.

[@AndreasSpiess]

Gern geschehen! Eine gute deutsche Erfindung.

[@BensWorkshop]

It is an exceptionally clever design as you say. I have seen someone else cover it too. Puts me in mind of a West German valve radio that did FM stereo. Because, at the time, radios in Germany were taxed on the basis of the number of valves in them, if I recall correctly it had 3, and two diodes in the FM to audio converter. People can do awesome work when resources are limited.

[@AndreasSpiess]

I agree. People are most productive when they have a problem to solve.

[@carelx7029]

Thanks for giving the genius the credits he deserves. It is an incredible device. On a sidenote: a charged capacitor can destroy the device. I made it a habit to discharge capacitors first. And at that price: have a spare one.

[@AndreasSpiess]

I agree with the capacitors. In the tube days everybody knew it because it hurt when you forgot it ;-)

[@iantill]

I am catching up a little with your more recent videos after following avidly as you discovered LoRa WAN and a hill of other useful tech and lab kit. Like many of the others commenting here, I also watched your original video on this and bought one of these testers on the strength of your recommendation. Of course I took it apart with near disbelief at how simple the hardware is and agree, it is the work of a genius. I agree with your findings as well - where I have access to some very accurate test kit at work, I've found these devices to be more than 'good enough' for my hobby work at home. Thank you, as always, for this content. I have always loved how rigorously you approach these subjects and the clarity with which you present them, making them both accessible to early career engineers and hobbyists, as well as interesting to seasoned engineers.

[@AndreasSpiess]

Thank you for your kind words! I try my best...

[@DanielLopez-kt1xt]

An extreamely useful device, i got mine as a DIY kit, since i like to make kits (it's a good soldering practice, and in the end, you end up with useful tools like this one). I can't recommend it enough. Get it as your first kit, and then use it to check all your next kit part's values... also, i got mine in june 2016, and is still running on the original 9v battery without on/off switch (it's still at 8.6V).

[@AndreasSpiess]

You are right. The batteries live forever on these devices! And I agree that one of those should be in every lab.

[@tookitogo]

The reason they don’t need an on/off switch is that they have transistor-controlled soft power that effectively disconnects the battery. The button turns on the power transistor, then a MCU output and second transistor hold the power transistor on until the MCU releases it again, allowing it to fully turn off again. (A second MCU pin is used to read the button state, so that another measurement cycle can be started without waiting for it to turn off.)

[@awesomefacepalm]

What a funny timing. Yesterday night. I was thinking about how a transistor tester works, and now you upload a video about that exact thing

[@AndreasSpiess]

Perfect!

[@kurtttttttt]

such a good video and very timely as I'm in need of this only a few weeks after you posted!

[@AndreasSpiess]

Perrfect!

[@Phettsack]

I love my universal tester, transistors, diods, resistors. Whatever, feed it in the tester and you know what it is! Magic!

[@AndreasSpiess]

:-)

[@MarcusPHagen]

I first saw this video when I was beginning to learn about electronic components. Taking your advice, I purchased a tester from Ali Ezpress. It has been extremely valuable to me, both in measuring components to verify their identity, & in obtaining correct values when it was critical for a circuit. Thanks to this & many other videos, I've gotten much more confident in both repairs & in new build projects.

[@AndreasSpiess]

Comments like that motivate me to continue. Thank you!

[@zyghom]

my first analogue multimeter had a socket (4 pins) for testing transistors (there was a time, when high frequency transistors had 4 pins - 1 was for chassis) - that was incredible - it was showing the gain factor (beta if I am not mistaken) - I am talking 35 years ago or so. Today the tester costs 1 coffee (at least in UK) and tests almost everything - eh, that is a progress sir! ;-) OK, sometimes tester is lost but still - for 5$? genius as you said (including the display, box etc)

[@AndreasSpiess]

Indeed, things moved fast since I was young. Today, it is a wonderful (electronics) world!

[@andymouse]

The guy's, Markus et al are legends...cheers.

[@AndreasSpiess]

:-)

[@GeorgeWMays]

An excellent video as always. Thanks a bunch. I love these testers. They are so handy for quickly checking parts. I'm sure that each of the capabilities of the tester was added incrementally until it reached the point that it could distinguish so many things. And I'm sure that along the way they had to figure out how to discriminate between similar components. The result is clearly a labor of love that we are all thankful for.

[@AndreasSpiess]

I agree that they did a great job particularly in recognizing the different parts...

[@elshiftos]

'No, Unknow, or damage....' 😁 The 2nd iteration I purchased drew approx 100uA in standby, thus draining a PP3 in a matter of months. My solution was to mod it to run off an 18650 with a charge circuit, plus a switch to disconnect it when not in use. I also bring the 3 test points out on short croc leads for added flexibility. Thanks for the interesting video!

[@AndreasSpiess]

Good idea! I added a switch to one of my devices

[@markwarburton8563]

I love my tester too. I've always wondered how it actually works. Thank you for doing such an informative video.

[@AndreasSpiess]

You are welcome!

[@GutsyGibbon]

Great video, just put in my order. Looks like a good way to learn (relearn) about understanding various components.

[@AndreasSpiess]

Absolutely! You will love it.

[@gregclare]

Another brilliant video! Kudos for giving the appropriate credit to the original designers, and for presenting the cleverness of these devices in an easily understandable way (that doesn’t require reading a huge technical manifesto!) 🤓

[@AndreasSpiess]

Glad you enjoyed it! And thank you for your kind words.

[@tenlittleindians]

I bought one years ago and printed a case for it. These seem magical when you first use them. It never dawned on me they were built around an Arduino chip. I have not checked lately but it wouldn't surprise me if the software has evolved enough to now test and identify most modern chips that will plug into the test socket. Where they really shine is part identification where the chip identification has been removed to prevent repairs and reverse engineering. Those manufacturer secrets ain't so secret anymore.

[@AndreasSpiess]

I assume we find one on most of our desks. Also to quickly test if a part still is working...

[@garyseaman6105]

Thank you for an informative video. He is a genius. I've recently got one of these, they are excellent if you're new to electronics like myself. Can check if you are reading your resistor values correctly. Very handy.

[@AndreasSpiess]

I agree. Mine is used nearly every day...

[@ekenpad8482]

There is a master thread on the eevblog forum where you can follow the updates to the original firmware and learn how to update your clone device with the original better software and install more accurate voltage regulators and precision resistors to improve its accuracy. I can't post the link for some reason, but it's easy to find as it's a multi hundred page thread.

[@AndreasSpiess]

Thank you for the tip! Comments with links are deleted on KZbin :-(

[@sanjikaneki6226]

i sw that too but there are so many versions atm

[@Sekhar_Home]

I have created this with atmega328p and 16x2 display. It was great

[@AndreasSpiess]

Cool and very useful project!

[@Sekhar_Home]

@@AndreasSpiess A big thanks for reply. I am now in a project about LoRa,ESP32 and GPS module for my own vehicle tracking and theft detection for my car. I have watched all ur episode about LoRa and it will definitely help me to build. Hope for the best

[@AndreasSpiess]

@@Sekhar_Home Look also at Apple's airtags. I use them on my bicycles...

[@nosafetyswitch9378]

Great video! I have the yellow version that came in an acrylic laser cut housing. I was really annoyed with the 9 volt battery because it wouldn't last very long and i always prefer to have rechargeable devices so i used a liion cell from an old Samsung device and a boost converter, a fuse for the cell and a toggle switch and it all works great now. Somehow managed to fit everything in the housing too. Amazing devices!

[@AndreasSpiess]

Interesting. My 9 volt battery lasts years. I do not remember when I changed it.

[@tookitogo]

Weird. I also have the yellow board version and the battery lasts forever. It has a proper latching power circuit that allows the MCU to disconnect the battery when off, so the standby power is essentially nothing.

[@tonysfun]

Love your videos Andreas! I have several of these inexpensive "testers" and use them also all the time. I like the T7-H, it has a rechargeable battery inside and color LCD also. Thanks Andreas!

[@AndreasSpiess]

Indeed a good choice. Also because of the case.

[@eldontyrellcorp]

I bought the latest version, it has so many more features now, it's totally amazing. I also ordered a case for it. For the price, it's a must have for every electronics hobbyist!

[@AndreasSpiess]

I agree!

[@AjinkyaMahajan]

Wonderful explanation Andreas. Based you your explanation, I will dry to make a cheap curve tracer with custom ADC, programmable voltage, current supply a microcontroller for USB interface perhaps a PSoC. I think there is a way to make a lock-in amplifier and 4-point resistance measurement with micros too. Cheers ✨✨✨✨

[@AndreasSpiess]

That is a very interesting project!

[@georgef7754]

Thank you. Now I have a better understanding how it works.

[@AndreasSpiess]

You are welcome!

[@qzorn4440]

i had no idea how these black boxes work. this fascinating description makes me wonder what else can be analyzed and reversed engineered. 😎 thanks for the cool 007 Q info. i have one of these Chinese devices and will shop around for a better one.. this time maybe one made in Taiwan 🥰

[@AndreasSpiess]

Maybe even you Chinese device contains chips made in Taiwan ;-)

[@qzorn4440]

@@AndreasSpiess thanks 😎

[@דניאלהלבין]

The diodes are for ESD protection, the ATMega328p is a 5V device so input is allowed to be 5V. However, if working at 3.3v, the input is not allowed to be more than 3.8V (Vcc+0.5)

[@AndreasSpiess]

You are right.

[@matzer8846]

Great in depth analysis! Thanks a lot for sharing 👍

[@AndreasSpiess]

You are welcome!

[@AttilaAsztalos]

Thank you for acknowledging these wonderful devices for what they are - no, they sure won't replace a suuuuuper-precise Fluke or Rohde & Schwarz lab instrument but they were never meant to do that, and they're MORE THAN PERFECTLY ADEQUATE to characterize a possibly unknown part you have just as long as we all understand the displayed values are NOT supposed to be taken as 0.00000... accurate. These things WILL tell you what a part is, and they WILL give you the CORRECT ballpark value. And for most enthusiasts who can't justify paying thousands of dollars for precision instruments that's really ALL they'll ever need. The amount of empowerment that this CHEAP thing grants to people who could never afford (or likely ever need) "proper" lab kit is impossible to overstate. Both the original firmware developers and the Chinese cloners are heroes in my book for bringing these things to the masses who could never hope to own anything more sophisticated than a DMM before.

[@AndreasSpiess]

I agree. We live in a very good time for the electronics hobby!

[@gregorymccoy6797]

I have one of these and played with it the first day I got it. I was very impressed. It's plenty accurate for the results I need.

[@AndreasSpiess]

I am sure it will be useful also in the future!

[@jmr]

I didn't know I needed this. Take my money! 💸

[@AndreasSpiess]

You will love it!

[@SomeGuyInSandy]

Cool video! I have one of this type of tester and wondered how it actually worked. Thanks :)

[@AndreasSpiess]

Now you should know ;-)

[@N1gel]

Great explaination.

[@AndreasSpiess]

Thank you!

[@mixza81]

Have you tested (and calibrated) any of these clones with official firmware? Any changes in detect accuraticy?

[@AndreasSpiess]

I do not think that they changed the software. Too much work, I think. But I never checked. I do not expect too much accuracy from such cheap devices

[@johnwest7993]

I got one in a box of electronic junk I'd picked up at a ham swap and wasn't sure how crude it was or how inaccurate. I'd never seen them before. Nor did I find the instructions on line for my specific unit, so I just figured out from the screen what it was and checked a couple of resistors with it to verify functionality, and set it aside since I have better gear to test a lot of various devices with. But out of curiosity I think I'll pull it out and see if it can distinguish the difference between a Schottky and a germanium diode. It seems like a very difficult test for a $10 device, but I might be surprised. I don't like to use test and measurement equipment as black boxes, just make a connection then read a display. I really like to 'grok' what's going on with the test equipment. So thank you for the detailed explanation of these little circuits, more ingenious firmware and inexpensive micro-controller magic. Detailed knowledge of the operation of my test gear helps me understand the interactions of it with what I'm testing, much like the quantum observer affecting the observed process. It keeps me from making the sort of stupid mistakes I made when I was young, like thinking a crystal was dead because I saw no waveform on my new o'scope after putting my 50 Ohm input scope probe on the leg of the crystal for the oscillator circuit. Duh. There's a lot to learn in electronics, and the first thing to learn about is your own equipment.

[@AndreasSpiess]

I would not call this a "test instrument". It is more a "verification instrument" and it is very handy because it is fast. Most of the time I want to know the pinout or if a part is working or dead. There is no better solution to answer such questions. I also think that learning electronics changed a lot. Starting with ICs and now modules we moved one level up (as mankind often did in the past). The current generation only needs to know the parts if it does not work and we can build lots of stuff without this knowledge. It still is good knowledge, but probably not for starting... I am often called if it does not work. The kids can do without me if it works, sometimes better than me because they do not care about the details;-)

[@johnwest7993]

Thank you for your reply. All very good points, just as long as we can maintain this level of device integration. I had observed this step up a rung on the evolutionary ladder of technology, but I hadn't considered its implications to a new generation of technologists. You have.

[@AndreasSpiess]

@@johnwest7993 They (as we had) have to deal with much more complex systems than the generation before and have to leave details behind. If I see what kind of projects I can finish in a week, it is mindboggling (Example: Build a sensor, connect it wirelessly to a server, store and display its results and maybe mix it with some data from the internet). It would have taken me much longer when I was young. In my opinion, each generation has the same span of complexity they can cope with. Just on different levels.

[@qwaqwa1960]

At least one of my testers was able to detect a depletion-mode MOSFET, and a 2-pin LED, internally with 2 back-to-back LEDs of different colours!

[@AndreasSpiess]

Astonishing!

[@annaoaulinovna]

great video topic. thank you so much! i need some details for crt oscilloscopes and transistor curve tracers and VI curve tracers andd fault detectors. your sound card scope video was so good.

[@AndreasSpiess]

I left a link to the curve tracer and Google finds many links to similar projects...

[@Doping1234]

Wow, the skill to make this work with so little. It's like watching a chess master play.

[@AndreasSpiess]

I agree!

[@paulskaar8556]

I'm curious to make a Marquand (forgotten inventor) map of the solution space (fingerprints) and see if I can reduce it, admittedly already knowing the answer, to something as simple Markus Frejek came up with. Crossword/Sudoku puzzle for electronics.

[@TechnoEveryday]

Great video as always. Is it still useful to use these devices to test in-circuit components on the pcb?

[@DanielLopez-kt1xt]

It depends on the layout, you can probably test some components like resistors, but keep in mind that in the pcb, there are tons of components usually running in parallel, that can affect the results, you can try to test them on the board, and if you see something way too off, take it out and test it again, but it's allways the isolated test the one that will work 100%

[@TechnoEveryday]

@@DanielLopez-kt1xt True that. Actually i have used expensive in circuit tester before. Wondering if this cheap solution is workable with MOSFETs and transistors

[@AndreasSpiess]

It works with transistors and MOSFETS and I agree with Daniel's answer.

[@DavidMsg]

I did a calibration and am wondering if this helps if the resistor values aren't within the tight spec (680r and 470k)? Or if I should replace my chinese model's resistors with closer values.

[@AndreasSpiess]

I never wanted to have more accuracy from these devices. So I cannot answer your questions :-(

[@saysphilippe]

Another great video Andreas! I really liked the 3d-printed case for this tester. Are the STL files available somewhere? I checked your sites but couldn't find it.

[@AndreasSpiess]

As mentioned this is an old video and I do not have the STL files anymore. I am even mot sure if I made them myself. You should find others, I think.

[@IanSlothieRolfe]

I have one of the yellow ones, I found a case on thingiverse that was supposed to work with it, but the dimensions on my board were slightly different and the hole for the screen was in the wrong place, so I had to design my own; I'd recommend just printing out the part where the board mounts and test fitting to your board before printing the whole case.

[@superblondmale]

much thanks for this very interesting & informative video! I always wonder if somebody had already adapted this techniques on the esp32 with better (external) perhaps 16bit dac-component. This would give us lot of possible enhancements.

[@AndreasSpiess]

I never saw it. However, the ADC in the ESP32 is not very good ;-)

[@AmitabhAnkur]

What a great video. 🙏

[@AndreasSpiess]

Thank you!

[@StefanoBettega]

I bought one of these testers and I was really surprised about their quality and capabilities. There are also versions able to decode IR commands.

[@AndreasSpiess]

I never used the IR functionality. Good to know it works...

[@FixDaily]

I have 2 different units, one like yours with monochromatic LCD and another with color LCD and encoder. The monochromatic works better than the colorful one. I've calibrated both, and for example mosfets and transistors, the colorful one has less clue how to detect them.

[@AndreasSpiess]

I also do not know why we need color for this application ;-)

[@laboratoriodeprojetos1351]

Great vídeo

[@AndreasSpiess]

Thank you!

[@serggorod1423]

14:14 одна из наиболее интересных сцен. One of the most interest scene.

[@AndreasSpiess]

:-)

[@ayan.debnath]

I bought this tester. One issue - It sees Axial Inductor as if Resistor! Can you pls check yours?

[@AndreasSpiess]

Not all testers support inductors.

[@mahadotube]

I created my own tester using an arduino nano, a 0.96" oled and i used the hex code from wiki of the creators of the tester. I preferred that over buying one because it was more challenging and fun.

[@AndreasSpiess]

I agree and you probably learned a lot by creating this device!

[@soulrobotics]

Hi. when I reapir old transistors radios, I need to know if the capacitor "is leaky" (*). sometimes, The capacitor tester told me the ESR associated with the capacitor at certain frequency, which is very handy. But what about the paralell resistance associated?... I am looking to the perfect capacitor tester. (*) if it let pass DC. I've heard about Mr. Carson's LVCT, but since I didn't want to be a patreon, I started to look for the people who build it. They make a huge mistake showing their versions, now I know how it works. I am not sure it can measure real leakage if you don't test it at the rated voltage... well i continue searching. Buy the way... you have to write a handbook. alles sauber und klar

[@AndreasSpiess]

Mr. Carlson should know what he does with testing old capacitors as this is his main business ;-)

[@sanjikaneki6226]

you said you have then one in the link and another one with the a knob could you please give me a link? Also do you intend to make a upgrade video where you add a better reference etc? also that documentation is huge and i cant even begin to understand the code with all those define statements PS DIY solar update when?

[@AndreasSpiess]

1. Some links should be in the video description 2. I will not do upgrades 3. The next solar video will air after my summer break in September

[@alexanderzohrens2945]

IGBTs und Triacs habe ich damit probiert. IGBTs werden sehr oft nicht bzw. falsch erkannt wegen der hohen notwendigen Gatespannung. Triacs , die hohe Ströme schalten können, werden ebenfalls nicht bzw. falsch erkannt.

[@AndreasSpiess]

Das ist richtig. Das Gerät hat ja nur 5V Versorgungsspannung.

[@jamesmor5305]

Which one of the testers do you prefer? To buy?

[@AndreasSpiess]

There are not big differences. I usually take the one which is closer to me ;-)

[@jaroslawpiotrowski210]

Hi, I suggest to use LCR-TC1 tester - it is much better - cost about $20

[@AndreasSpiess]

Thank you for the tip! It looks like a very similar design. But I like the case! What is not needed is the rechargeable battery. My 9V battery works for years.

[@californiakayaker]

Yes, I =have always thought of these devices as miracle devices. I studied my suspicions of its origin about 5 years ago. I've got a little white one with a nice case now. Who knows what is next in testers ? If we had these when I first started in electronics I might have made money, as it was I starved !

[@AndreasSpiess]

I am not sure if they will get better for this little money, I think. I agree, it would have been good when I was young!

[@greg4367]

Good morning Andreas, greetings from San Francisco

[@AndreasSpiess]

Greetings back! Nice city!

[@samehwaheed3882]

please if transistor or capcitot are not working whats he do?

[@AndreasSpiess]

I do not know :-(

[@emilalmberg1096]

Greetings from Sweden!

[@AndreasSpiess]

Good morning!

[@TheEmbeddedHobbyist]

Its not a good idea to expect that all sensors will have a series resistor on the output pin. A sensor with a fast switching output it could start to look like a low pass filter. Plus if the sensor 5v comes up before the 3v3 you will try to power the esp8266 via an io pin. Which can lead to strange behaviour or latch up of chip.

[@AndreasSpiess]

Is this comment for this video? It does not make sense to me :-(

[@TheEmbeddedHobbyist]

Hi Andreas, the comment is not strictly on topic but in relation to a statment you made at 6.08 minutes in to the video. 1. You point out that the ESD protection diode in the chip will be protected by a resistor in series with its output of an attached sensor. I was just returning with a commenent that not all sensors would have a series resistor in the output or fitted to their PCB's; it could be directly from a gate with a strong 5V output which could make you chip curl its pins up. It’s good design practice to design for the worse case where there is no protection and incorporate your own. 2. It’s not a good idea to pass current though the protection diodes as this can lead to chip lockup or the input drawing too much current. 3. Also if the 5V is provided externally it might be present before the chip is powered, this can lead to allsorts reset issues within the controller. As the current through the ESD diode will be back feeding the internal power supply of the chip. sorry for any confusion

[@transientaardvark6231]

I thought a similar thing when I saw that. I would say that if you have something that you know is going to put out 5V then you should at the very least be putting some resistance between the 5V output and the 3.3V input, otherwise you could be setting yourself up for very high current draws while the 5V and 3V3 rails fight a proxy war through the output driver and the input protection. The volts you need to get rid of are approx (5V-0.1V) - (3.3V + 0.6V), or about 1V. so 1K limits this to 1mA. (After that you need to think about whether the low-pass filtering of your signals through the series resistor is going to problematic)

[@AndreasSpiess]

@@transientaardvark6231 Now I understand. You are right, of course. This is a hobby channel, and I shamelessly simplify things. Fortunately, I usually can depend on the chip designers who will correct these mistakes... Most sensors I use have extremely limited output current capabilities. I try to avoid 5V signals at 3.3V inputs because some chips will die (like the Raspberries).

[@pekkaritamaki8858]

Hey, it was very nice a meter. I have bought this three times, but I can't find the manual ( RTFM). Could you give to me? I have made external Nokia 3310 LiOn battery + inverter to 9V + 2.5m mm 4.1V power connector. Pekka R, Finland

[@AndreasSpiess]

The link should be in the description

[@Electronics-Rocks]

One problem with these testers is vintage equipment on testing diodes. A switching power supply diodes tested good BUT using my CRO component tester the faulty diodes looked like zener diodes not standard diodes due to the low voltage used in testing! I have not bought one of these cheap testers yet just repaired PSU which others have had troubles due to their beliefs of these testers. So many trust in what they see or lack of knowledge of the limitations of these devices.

[@matambale]

Agreed that it doesn't answer every possible test need - the 5v limit restricts its usefulness, but at $10, the price/performance ratio is excellent. I just wish we could purchase it directly from the original inventors. It is a very useful first-line diagnostic tool.

[@AndreasSpiess]

You are right. They have a very limited voltage range and therefore can show wrong results. I once saw a simple DIY tester for Zener diodes with a higher voltage.

[@Mr.Leeroy]

how does it determine polarity of ECaps?

[@AndreasSpiess]

I do not know if it does. But I also asked myself the question. It shows the same value for both directions. Maybe it does 2 measurements and selects the bigger value?

[@Mr.Leeroy]

@@AndreasSpiess at 14:57 you can see on the scope charge curve of cap right to the 63.2% of 5V according to time constant equation, so ~3.16V. Not sure if any ECap can be damaged with reverse polarity charge at such voltage levels or not, or even if it will take charge at all.. I guess it's a good subject for experiments.

[@Autotrope]

A lot of these seem to have 3.7v lithium batteries in them now which seems like a really poor choice for something where the battery otherwise lasts a very long time.

[@AndreasSpiess]

Mine have 9 volt batteries if I remember right. But you are right. They last forever and a rechargeable battery is not a good choice.

[@jaytalbot1146]

Creepy, I just ordered one of those testers today (using a different computer at a different location), and now KZbin is recommending this video (I didn't search for it) Big Brother is Watching You!

[@AndreasSpiess]

Better it suggested something useful for you ;-) Without "big brother" maybe it would have suggested something completely useless ;-)

[@BX2ABT]

I ordered one from AliExpress not knowing how interesting the background of these testers are. Thanks for the excellent explanation. Unfortunately my tester arrived DOA, but luckily AliExpress will refund me. Have to order a new one now.

[@AndreasSpiess]

Hopefully, the next will work!

[@TinySpongey]

A word of warning to anyone purchasing one of these. Some of the more recent clones are of much lower quality. They don't use crystal oscillators any more which reduces the accuracy. They use "fake" incompatible MCUs which means you can't upgrade the firmware with the open source versions. A flaw in the circuitry can damage zener diodes. Some have pretty colour displays with fancy graphics but have removed many of the features to support this. Unfortunately it's almost impossible to tell form the listings which version is which and they rarely show pictures of the inside. For more details see the big eevblog thread.

[@AndreasSpiess]

Thank you for the update! I assume they did no more get the 328 chips...

[@Chris-rg6nm]

His name was Markus Frejek

[@AndreasSpiess]

You are right. I thought I mentioned his name here: kzbin.info/www/bejne/mIPXfZ6HbcmCoJI ;-)

[@AmitabhAnkur]

I have rotary switch one.

[@AndreasSpiess]

:-)

[@sarkybugger5009]

These things save so much time, and are a lot less taxing on the old eyeballs than squinting at tiny text, or coloured bands on coloured components... Money well spent, IMHO. I have had mine for at least five years, and it's still on the original battery.

[@AndreasSpiess]

Indeed, the power consumption is extremely low!

[@ishdemon_]

Still waiting for diy solar update🙏

[@AndreasSpiess]

I am still in the Summer Break :-(

[@joseph9915]

May be just me, but the alie links don't work.

[@AndreasSpiess]

Maybe you use an ad-blocker?

[@qwaqwa1960]

What's so special about the BS108...?

[@BerndFelsche]

I suspect the junction diode.

[@AndreasSpiess]

And the package.

[@qwaqwa1960]

@@AndreasSpiess What...? Neither reply makes sense...

[@AndreasSpiess]

@@qwaqwa1960 You hardly find FETs in TO-92 cases. Most are SMD or TO-220

[@qwaqwa1960]

@@AndreasSpiess Maybe more uncommon now than in ye olde days, but what's the connection to tester behaviour...??? None. Maybe you got "special" Chinese FETs...

[@alexanderzohrens2945]

Klar...In der Schweiz kostet so ein 10$ Tester 10 Millionen.... jemand, der das nicht glaubt sollte mal einen Manager der Credit Suisse fragen.

[@MahBor]

Can you build one yourself?

[@AndreasSpiess]

Maybe. But not for this price...

[@MahBor]

@@AndreasSpiess Thanks!

[@alexanderzohrens2945]

Accuracy...mal präziser aussprechen..

[@kpkpkpkpkpkpkpkpkp]

chinese r sweet peoples

[@AndreasSpiess]

Sometimes...

[@JessGade]

Argh ... I need to stop seeing these videos! ... Always leaves a dent in the wallet afterwards...

[@AndreasSpiess]

I agree ;-)

[@paulcohen1555]

I know who was the original inventor. I also know that chinese are copying this and other Western products. "Bad behavior" isn't strong enough to describe the chinese behavior.

[@AndreasSpiess]

I agree that this behavior is not as we would like. At least it seems that they do it also with their own competitors (e.g. NanoVNA).

[@paulskaar8556]

Markus Frejek....all hail the estimable inventor😁

[@paulcohen1555]

Ha, Ha, Ha. "The capacitor is too small". Some chinese factories will print on the components whatever values a distributor wants. Of course the factory name is fake. Go find it in china to complain or sue them.

[@AndreasSpiess]

Fortunately, I am an Engineer and not a lawyer ;-) BTW: I have many proper capacitors from China, particularly SMD parts.

[@paulcohen1555]

@@AndreasSpiess Sure, they also make good products and that's why I can't understand why there are so many counterfeit items. And to be safe, always chech what you are getting 😁

[@AndreasSpiess]

@@paulcohen1555 Exacty that is what I try to do. And file a dispute if they are not ok. To show them that it matters.

[@Redone-jp6uz]

Same video twice 🙄!

[@trhosking]

Pay attention. Andreas is still on his summer break and is reposting some of his more popular videos. I hadn’t seen this one before so I’m glad he did.

[@AndreasSpiess]

Both are right. And the fact was mentioned in the intro as well as in a pinned comment to save you the time for re-watching ;-)

[@Redone-jp6uz]

@@AndreasSpiess Thank you so much. It was a incredible education video.

[@Hauketal]

Small error in the diagram at 11:30, the name is Schottky with a "c". See en.wikipedia.org/wiki/Walter_H._Schottky

[@AndreasSpiess]

You are right! Thank you.