All You Need To Know About MOSFETS To Fix Stuff! How Mosfets Work Fail Test In & Out of Circuit

Maybe fix the video early on cause if you're trying to learn and only watch half the video you'll be completely screwed.

Extremely great channel

MOSFETS act just as the old values do- a field device (that's my understanding.)

Thanks for sharing this, just one question, for p channel MOSFET let's say it switch on by 10v to source and 5v to gate, from another power source I want to put 50v to source and connect it to load from drain, would this work or no?

One of your best videos in my opinin Richard - thankyou for posting.

Thank you 🙏

Fantastically

fantastic!

Very interesting. I only ever had the most rudimentary of electronics knowledge as a teenager, with BJTs in switching applications being the limit of my skills. AC and amplifier circuits were completely beyond me, and I barely even knew what FET stood for, let alone how to use them. Now, mumblety decades later, I'm trying to learn some of these things again. Components and test equipment have become ludicrously cheap and accessible, something that was not the case in the early 1980s for me. I'm trying to go slow-and-steady, starting to dabble with JFETs before breaking into my stash of MOSFETs, but it's good to build up some knowledge for Future Me. One thing I hadn't realised until it was explained and demonstrated here in this video, was the concept of capacitance and a MOSFET remaining switched-on when current is removed. I genuinely didn't know this. I find myself wondering whether that retained charge dissipates over time (when out of circuit) or whether the transistor effectively remains "on" for a number of minutes, hours, days or weeks. Another part of this is a loose concept bouncing around between both my braincells, about this potentially being used as a form of (perhaps short-term) non volatile one-bit memory. I can see the entrance to a particularly deep and twisting rabbit warren nearby...

I have a hexfet part number IRF2204S that seemed to have been smoked from an overloaded small motor on tennisball machine .. rendered the entire PCB and system unresponsive to input

When testing, I just can't turn the gate on with the multimeter. But if I use my bench variable supply set at 9 V, it works fine.

Another thing, probably mentioned somewhere else, but if you work with an antistatic mat it won't do to test the Mosfet over that. These mats are conductive and they will discharge the gate capacitor as soon as the terminals touch the surface.

Early on in the video, you said the mosfet was a bi-directional device, so that current can flow between drain and source in both directions. Surely this is not correct because the body diode needs to remain reverse biased so that with an N channel device, the drain remains positive with respect to the source and current flows from drain to source.

Too many mistakes and corrections in this video, makes me wonder whether you know what you are talking about!!

Loved this! It was very helpful! Thank You and please keep making such videos.

This channel is a little gold mine of information and clearly explained ,
I have searched high and low to get a clear understanding of such, so thank you so much for making this video as i have learned so much with in the hour and have not wasted years with all the complicated Bla Bla Bla in text books that fries the brain just like an over voltage Cap.

Youare the best lecturer on all issues electronics in my humble opinion and you're a brit that's a plus, go Liverpool. Do you have any videos on tracing a problem where you don't have power to the VCC. I am dealing with a power supply for an Anton Bauer quad charger. And I cannot seem to trace the root of the problem. No Power to both switching chips, they share the VCC and it gets 16V. I traced it to a W1P transistor that gets 17V at the collector but it doesn't release it to the emitter which would go to the VCC as probably 16V.

Mosfet N- channel possible failed when it warm? Because when its cold I have negative signal and when it warm is nothing.

Wow, my head is swimming...but I know much more about the four types of mosfets than I ever did before. Inching towards making sense. Thank you so much.

I found your videos really educational for someone like me. I wonder if you check questions here. I got a question hoping to get your answer. I recently mistakenly connected an old PC power supply’s 12v output to a 26v battery, I hear two loud explosions and the supply was burned. I found the 16v rated 1000uf capacitors were blown open. But after replacing the two capacitors, the power supply is still broke. What else do you think could be damaged?

So what your saying is that current, the actual electrons, flow from positive to negative.
Because I thought, that to have a positive charge, there must be less electrons.
An atom with a missing electron becomes positively charged. And it wants to be balanced again. So WHY dose every one keep saying otherwise?
I have read the arguments and frankly, to me, just poor excuses for people not wanting to correct an error made over 200 years ago.
But then, that is human nature...stubborn, problematic and if it doesn't personally benefit...why bother?
I think this is one more reason AI will process against humans.

But then, what do I know?

As for every thing else...Nice!

What's up with laptop mosfets when a laptop dies generally i go after the mosfets, i always mock them on laptops, but why they fail so much? but especifically on laptops i mean a desktop has a pc that has like 3 or 4 mosfet on the power supply to push a lot of power, i know that is not fair since them work at 3 digit voltage hence lower current but a desktop motherboard has mosfets for the cpu that are beaten up to ridiculous amounts of current and a desktop motherboard (at least in my experience) rarely dies of that. so what's is going on with laptop mosfets? they doesn't go overkill on laptops as on desktops?

the fact that the pen is at 1% makes me both anxious and surprised is quite the feeling

Hard to watch with all that hair...

Anyone have any tips for finding someone good locally who works on stuff like this?

I have a several repair projects (I'm just a hobbyist) that I've traced the trouble to tiny little components on very crowded boards thst I don't have the tooling or skil to fix. They are old family items that I don't want to hand off to just anyone.

Love your work, well explained detail to detail. As a troubleshoot technician I found a voltage difference on a transistor and could not comprehend what was going on internally until I watched this video. 💯👊

Great video Richard you answered a lot of questions for me for sure,keep the good videos coming.

For the life of me i just can’t seem to understand mosfets

Very good and this is an awesome explanation.

Again, a seamlessly delivered compendium of knowledge. If only they had taught us this way in the technical colleges of the late socialism in eastern europe... Cheers, Richard!

Awesome tutorial, loved it! Thank you!

great , thanks for sharing 👍

So well explained , no professor could explain it rather than equations on the board.

Hi Richard, although I would call myself advanced when it comes to electronics, I love your "All You Need To Know About" series. And I still learn a lot through them. Sometimes I learn something new, but most of the time I remember something I had forgotten. Thank you for taking the time to make these series. Again, I love them!

Hi I'm very new to the channel And absolutely thoroughly enjoying The videos So thank you for all the time you spend on them
I was wondering if It's possible for you to do a video on 100v line amplifiers
I have Recently purchased one to use as a outside garden audio system But it is very limited on output wattage I would really appreciate and love to see a video on these and how to Increase the output wattage
Thank you

Hi Richard. Did you mean input resistance high on bjt? I'm lost on that point. To keep base current low would the resistors need to be high? Thankyou

Thank you soooo much, I have been working in the field for 20 years, repaired a lot of equipment by using sight, and experience. Had I known this information I would have fixed a lot more equipment. Thank you for sharing in such simple terms.

Hi Richard, I know I am a bit late to the party but I just joined so please forgive the tardiness. I feel the need to add in one point for those that might be new to mosfets, the gate resistor you have drawn in your mockup relay diagram is going to +Ve, that means that you are using the resistor to power the mosfet "on" there are other circuits in which the resistor will actually go to ground to turn off the mosfet, this depends on A: the circuit design and B: the semiconductor you are using to switch the mosfet with. In your circuit with the relay you are using whatever is driving the mosfets gate to "sink" the voltage from the gate to ground on other circuits with the resistor to ground the device driving the mosfet will be the "source" of the voltage for the gate to turn the mosfet "on" and the resistor will discharge the mosfet gate to switch the mosfet off.... The other point one might add, is that N Channel mosfets "typically" have lower resistances between drain and source compared to P channel mosfet and therefore also higher current capabilities sourcing P channel mosfets with low resistances and high current capabilities can become quite expensive compared to N channel mosfets of the same characteristics. Mostly it depends on the circuit use and design. I just thought that it might be prudent to add this point in.

Thanks for all these superior quality videos! Could we get an episode about motherboards?

Wow, awesome video. Thank you.

Very clear and to the point lecture. Thanks a lot.

Heya not sure if I understand all of it gone watch this a agin on a later time stip but still learned a few things ( because of my autism I need to see it a few time to understand)

I have an ebay listing for a powejack pswgt-1200. I have replaced the igbts a few times at high cost and given up. If you are interested in a challenge place a bit, it's for peanuts, and hope you can get to the bottom of the problem, I would be really interested. I'm done on it. Great channel, great info, keep up the great work. Cheers.

very interesting.I learned a lot about MOSFETS. I know junction transistors and vacuum tubes.

Wow...! What a beautuful presentation .....

Thank you for the video. Very nice explained.

Great video! I wish I had a teacher like this. All teachers started their courses with complex mathematical equations. They failed at teaching how to think intuitively of how a component is used in a circuit. It was all about solving equations and calculus 🙄