The Amazing DIY $1 In Circuit Transistor Tester : Bipolar Mosfet NPN PNP N Type P Type & More

Here is something I've been meaning to do for a while. A cheap DIY tester for Transistors and MosFETs in circuit. You can build this for one dollar or less! This video includes schematics, construction details and how to use
Mentioned in this video
DIY In Circuit TL431 Tester
• How to test TL431 / KI...
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Thank you
Richard

[@leviathanmac3053]

Reading the comments, some people miss the whole point of these educational videos, keep up the good work Richard, there are a lot of us who appreciate both what you do and how you do it, shout out to Det and Carlos as well.

[@pault6533]

Many useful almost-free projects spread all around my lab. A fun way to put old parts to good use, instead of sitting around in bins and boxes. I always appreciate these videos. They probably don't generate very much income, so each one is like a little gift to the community. 🥰

[@petero8875]

Explaining basics in a practical way at it's best. Please continue in your down-to-earth style, Richard! Nice one!

[@Rasspor]

I always manage to learn something new and interesting from your content. Please continue to provide us with great content Sir! Thank you for the content you have already created! Love your videos!

[@cskeet1320]

Hi Richard, This is inspired! Looks very useful for testing transistors that are difficult to remove or on fragile PCBs. It was only at 13 mins I realised what was going on here. Great stuff as usual. Lovely.

[@andymouse]

This is indeed an interesting and educational video ! I personally won't be making the device but i'm sure your less experienced pupils will have hours of fun and gain valuable electronics insight unraveling this one....cheers.

[@markusbecker3136]

Perfect timing, Richard. The other day, I ordered a fancier multimeter and I was about to sell the old one. Now I’m going to keep it.

[@garypoplin4599]

Before I even watch further, I’ve already seen the origin of this idea in your video “All You Need to know about MOSFETs to Fix Stuff” at time fifty min and five seconds (testing MOSFETs in circuit with two multimeters). I’ve been using the two DMM trick for testing MOSFETs for quite some time now! I’ve built a circuit make it easier to hold the different leads on the device. I think that’s what you’re doing here.

[@kgsalvage6306]

I was thinking the same thing. Putting the switch into a small project box. Using female banana jacks. I would use the higher voltage type for at least the 3 probe side. Then you can use any meter probes. Maybe put a small peice of green heat shrink on each end of one lead. You could also use mini grabers if you wanted. The trigger and measure sides, the banana jacks wouldn't matter. Just use male to male jumpers. Amazon has 12 pin 4 pole 2 position on/on switches for $8.99 USD. 2 pcs.

[@68CHUCKLES]

Tweezer test leads and footpedal switch would make it even easier !!!

[@Foobar_The_Fat_Penguin]

Nice and simple! 3 things to mention: 1. If someone doesn't have a second meter, they could probably use a LM317 or something similar to build themselves a CC source for the trigger, no? Might also get you a higher compliance voltage to turn on some less sensitive devices... 2. Now you need to get yourself a Detlef and make a posh Arduino project (replacing the meters with ADCs and such). 😉 3. A slightly more complex project similar to this can be found as a community project on the Elektor magazine homepage. It uses a 555 and two transistors to create a square wave which then uses the DUT as a switch to flash one of two LEDs (representing either NPN/N-type or PNP/P-type). Maybe it's worth a look. It needs more parts but doesn't require meters or manually switching between modes (NPN/PNP).

[@LearnElectronicsRepair]

Only problem with using the LM317 in CC mode as the trigger is you lose the display that shows the gate/base voltage therefore it is not possible to tell if this is a bipolar transistor or mosfet.

[@Foobar_The_Fat_Penguin]

@@LearnElectronicsRepair True. But if you don't have a second meter (e.g. as a beginner), I'd argue it's still better than nothing. At least you'll know whether it's faulty or not.

[@LearnElectronicsRepair]

@@Foobar_The_Fat_Penguin Agreed 😀

[@CXensation]

Clever little circuit. Well done Richard 🙃 You could use mini hooks for more comfortable probing, but that is luxury which always costs extra 😋

[@hschack]

Hi on the triac test you put the trigger om MT1 pin from Left to Right 1 2 3 3 is gate (nice video)

[@gd2329j]

If I understand the circuit correctly all you need is one extra probe with two 4mm plugs for the common . If you're testing a part you'll probably have some idea what it is ! So just flip meter connections for PNP or NPN . No fancy switching is needed !

[@gillesparisien4383]

Can i do tthe this with a analogue meter for the triger or the mesure meter n by the way u are very good at explaining the logix of electronic thank you by far the best channel for me

[@ionutzionutz7106]

Hello. Very good idea with 2 multimeters. Has anyone tried this method on germanium transistors? I worked a few days ago with germanium transistors and I noticed that there is some value between the collector-emitter, measured on the diode-beep. At trans with silicon between E-C we have "zero" on the multimeter. I ordered 2 cheap multimeters on Aliexpress and I will try this connection stile... Thanks Richard for these wonderful videos, this one and more...

[@chillidogkev]

I am not ashamed to say that I found all of this somewhat confusing but I definitely understood what was happening. However, I see very little value in assembling all of this and the fiddly technique required to hold three probes as anything better than a single meter in diode mode and some decent knowledge of how to use it. Is that fair or did I miss the point of it all?

[@Tims_Projects]

Great Idea, I wonder, could you do an improved Mr, bleep? Say add another LED for short.

[@GiC7]

Master

[@amdbtk]

Little cumbersome, but good idea. Keep up the good work. /Tamas

[@LearnElectronicsRepair]

Yeah I have an idea about making it less cumbersome but it would cost more LOL 😉

[@g4z-kb7ct]

All very good but it's a common beginner mistake to see a nice idea, take several hours to build it, find it doesn't work or they don't understand it and then give up. The proper way is just remove the part and test in a ten dollar component tester... 30 seconds and job done. Same goes for endless checking with a scope on digital ICs like logic etc. It's quicker to pull the part and test it externally using a IC tester. People doing a lot of repairs already know this ;-)

[@k3ggaming926]

That how i learn by my self 😂 lots of process manually

[@mikebond6328]

The proper way is to throw it out and buy a new one.

[@LearnElectronicsRepair]

How about the SMD transistors glued to the PCB with epoxy like that Basic 400 Amplifier I was repairing a couple of videos ago?

[@g4z-kb7ct]

@@LearnElectronicsRepair They are easy to remove if you know how lol. I've been removing glued smd parts for ~20 years. The better testers have smd pads so put the part on, hold it and test it. It's not a radical idea, it's the best use of time.

[@LearnElectronicsRepair]

@@g4z-kb7ct Clearly this project is not for you, no worries. I wouldn't say there isn't any 'proper' way of doing anything in electronics repair, usually there are several ways to approach any problem and I would just suggest do whichever works for you and not worry too much how others are doing it.

[@grahambambrook313]

Roy Rogers, not The Lone Ranger: his horse was 'Silver' 😆

[@andrew_koala2974]

The name of the horse ridden by The Lone Ranger was indeed ' Silver ' The name of the horse ridden by Roy Rogers was named Trigger. What was the name of the Horse ridden by that other Cowboy. R.R. The answer is Mrs Reagan And I won't ride anything that has a dick bigger than mine

[@LearnElectronicsRepair]

Yeah I'm not good wiith westerns LOL 🤐

[@grahambambrook313]

@@LearnElectronicsRepair I suspect you're just a bit younger than me!🤣

[@emersonmattoz3794]

how can i measure caps esr with no esr meter..?????

[@gd2329j]

You have options ! Oscilloscope & signal generator then do the maths . Pass music through the cap & use a signal tracer on the output . Make a esr meter . A 0.5 R minimum unit is easy & a problem component is probably over 8 ohms or open . If you need better than 0.5 ohms in circuit testing go shopping !

[@2009numan]

trigger was roy rodgers horse nothing to do with the lone ranger

[@2009numan]

why would you have two or more multimeter's surely one would do

[@mikebond6328]

😱

[@Lyndalewinder]

Ive got 3 😏

[@Lightrunner.]

Seven i have (one of these are my head, the most important)

[@michaelridley5457]

I also have quite a few..

[@GaryLaRocco]

Three bench meters on my bench, another 5 on a shelf - maybe eight handheld DMMs... They kinda multiply over time. ☺ You need a minimum of two for measuring both voltage and current at the same time.

[@dalevanderzee4086]

lol if you have broken meter leads lying around for years, that is called junk collection :)

[@LearnElectronicsRepair]

You may be surprised how much junk I have lying around 🤐

[@TheElectronicDilettante]

Spaghetification, only as a person crosses event horizon of a black hole.

[@2009numan]

I'm sure you couldn't build that for $1

[@pault6533]

How many of you get a pharmaceutical advert to treat Bipolar medical condition when starting this video?

[@LearnElectronicsRepair]

The ads are targetted, apparently 😜

[@ohboy4784]

1$? that is BS! Using the 2 DMM's is at least 10$ (if not more) for the crape-est extra DMM . Just use a single DMM the traditional way, it will take a few seconds more. This is absolutely not needed.

[@Lightrunner.]

😴😴 Who care's your opinion.👎 Make your own channel and let us show your knowledge . 🤣🤣

[@mikepanchaud1]

Did you watch the video? It's made from scrap or existing parts. It's an educational video, but you know everything already.

[@mikebond6328]

The crapiest multimeter is at harbor freight for $5.

[@LearnElectronicsRepair]

Now I did mention that did not include the multimeters and I didn't show them on the thumbnail either. Anyone interested in building something like this surely has several multimeters already like every other hobbyist and knows how to use them... and anyway it does not repurpose the multimeter like you can't continue to use it for other purposes as you did before 😉 I made a video a few years ago called the Amazing $1 short finder and that also connected to a multimeter but no one raised an issue over that, hmmmm

[@Lightrunner.]

@mikepanchaud1 ,, @mikebond6328 ,, mostly my project are made from scrap, spare parts and so on. My first voltmeter was a analog BBC after that comes a Metex 3650 payed from my first own money and i used it for about twenty years. If you have nothing or less with your own ideas you can move worlds. The electrons don't care whether the components are old or new. Appreciate the value of the things you have. Your own knowledge leads to the goal. Not the tool, the knowledge.