433 How Transistor Testers Work and How to Use them? 

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

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

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!

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.

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

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!

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.

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).

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

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.

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

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

Great information about these tester Andreas. Thx.

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

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

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.

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)

Great in depth analysis! Thanks a lot for sharing 👍

'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!

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!

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!) 🤓

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.

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

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.

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

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.

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

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!

Thank you so much. Order already in. Thanks again.

Great explaination.

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.

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.

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

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 ✨✨✨✨

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.

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 🥰

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!

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.

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)

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

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.

What a great video. 🙏

Great vídeo

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.

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

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!

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

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 !

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

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.

Afternoon Andreas, hope the summer is going well.

Greetings from Sweden!

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.

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.

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.

Good morning Andreas, greetings from San Francisco

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.

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

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.

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

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

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.

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.

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.

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.

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

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

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

I have rotary switch one.

how does it determine polarity of ECaps?

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.

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

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?

His name was Markus Frejek

Still waiting for diy solar update🙏

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.

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

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

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

chinese r sweet peoples

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

Can you build one yourself?

Same video twice 🙄!

Accuracy...mal präziser aussprechen..

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.

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.

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

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