How to use diodes, schottky diodes and P-FETs to protect your circuits from reversed voltage/power connections. Website: www.afrotechmods.com/
КОМЕНТАРІ: 1 000
@Afrotechmods6 років тому
Interested in learning about wireless power? Subscribers can get up to 80% off Wireless Power to the People - Wireless Charging 101 on udemy using the coupon code "UKposts" www.udemy.com/wireless-power-to-the-people-wireless-charging-101/?couponCode=UKposts
@CaptainDangeax3 роки тому
thank you for this very usefull video. I know what to do with all those useless mosfets I got on dead PC motherboards
@niceshotapps12333 роки тому
What if my load is a battery? Will PMOSFET also protect me from plugging the charger to the battery the wrong way? Or will the voltage from battery keep PMOSFET open and everything will go in flames?
@CaptainDangeax3 роки тому
@@niceshotapps1233 The charger already provides a diode bridge rectifier and a fuse. Plug it the wrong way a the fuse will simply blow
@niceshotapps12333 роки тому
@@CaptainDangeax Aparently when the load can provide its own voltage, one mosfet is not enuough. You need at least two and two resistors to avoid blowing fuses or something more valuable. www.analog.com/media/en/technical-documentation/application-notes/AN-171_AN-1568.pdf
@CaptainDangeax3 роки тому
@@niceshotapps1233 My point is why would you use such a protection on a battery charger ? Of course it's perfectly fit for any electronic appliance with external power supply, but for a battery charger, I don't see the point as I already wrote
@universalsailor10 років тому
This series is excellent. Easily the best electronics tutorials on UKposts that I've run across. Someone please give this man an award.
@brycejcox5 років тому
Ok, I’m here. Sorry for the 4 year delay but please understand there’s a major backlog for UKposts commenters requesting awards. With that being said... Hear Ye Hear Ye! We gather here today to recognize Afrotechmods for his stellar video tutorials that have gone above and beyond in helping others. His no bullshit approach combined with clear and concise dialogue alone was far more than his competition could come up with yet even that wasn’t enough for Afrotechmods. In a game changing manner, Afrotechmods set the bar higher than Willie Nelson at Snoop Doggs pool party by making a video without a single fucking digression, a feat many UKposts viewers believed to be impossible. We Salute you, Afrotechmods!
@ajaychandrawal97673 роки тому
True
@harrymartin166111 місяців тому
Why dont YOU give him an award?? Allways the others should do it...
@Escatrax9 років тому
Very well explained!! and the ironic thing about this is that I graduated as a electrical engineer and I never learned this at college. It's funny that I learned more about electronics on the internet than in school.
@Escatrax9 років тому
hehe, yeah that's true what you say. the thing is, that in college I only learned the basic. I learned all the components but never learned how to combine them all together to get a more complex circuitry. But like you sad, you probably need an eduction before you can understand this.
@arthurthegreat2169 років тому
Escatrax I don't know, I'm not in EE, I'm in physics but I feel like I learned a great deal from the few electronics classes I had. Aside from learning about circuit elements themselves, I learned a lot about filters and how to build them, about transistors and op-amps, digital logic and many analogue and digital circuits. Even though it's not the focus of my studies, I've acquired enough electronics and programming knowledge to do some serious projects and keep expanding my knowledge. The key is to actually use what you learn; apply it or you're gonna lose it.
@kevinwright2859 років тому
Escatrax ..no substitute for experience eh?.....I had a professor trouble shoot a simple relay logic alarm shunt circuit and he had real trouble dealing with the physical components .....he was a professor of engineering at UC Berkeley..... I told him I do this everyday...he replied yes but I design integrated circuits with millions of gates....apples and oranges...you have to use it
@josephcote61208 років тому
+Escatrax It seems to be a common experience among my technical friends that no matter what you learned in school, no matter how hard your projects were, your first real job assignment will be nothing you've seen before. There will be more learning on the job than you ever learned in school. But at least you're prepared.
@pbarnrob6 років тому
Every fresh-out BSEE, we hope, gets to learn this; in your first (and Every Subsequent) job in industry, you learn more. School only gets you ready to learn what you need to know. Managers have to know this to be good ones; and they get to train you in The Company Way of doing things, wherever you went to school. Watch out for the guy whose 'ten years of experience' is really 'one year of experience ten times', and stopped learning. At 72, it's a Good Day when I learn something new!
@jomac_ph5 місяців тому
2023, 11 years on and this still helps a lot of us. Just dropping this comment to wish you well, and hope that you're living your best live. Warm regards from Manila, PH
@georgekot63778 років тому
Just wanted to say you make the best tutorials !!!!!!
@Afrotechmods8 років тому
+George Kot Thanks!
@KhalilEstell7 років тому
Agreed!
@chems7 років тому
or use a diode on the + and - backwards so that it will short circuit ur power supply if connected backwards for dirt cheap and effective reverse polarity protection :)
@zet0korp7 років тому
If your 'power supply' is a non protected lithium polymer battery, that's not going to be pretty
@Hasitier7 років тому
With a proper rated fuse or polyfuse this could work
@silasfatchett56938 років тому
Just as your other videos, a clear and concise explanation of an electronics concept. Thank you.
@DeadKoby8 років тому
Props to you for making electronics understandable to the rookie. Years ago, I took an electronics class at the college. First off, I didn't understand jack about what was really going on.... with a few exceptions. But I knew how to calculate stuff, and if I built the schematic right, it worked. Thus I got an A. Boy did I fool them. Later in life I'm exploring electronics again, and I'm pleased that there's lots of good videos that explain this stuff in a less technical fashion... so a rookie can get it.
@str0g12 років тому
In the past, mosfets and co. was black magic for me. When I saw your tutorial videos, I understood it + the datasheets of mosfets make sense now. I really appreciate your time spending such good clips and hope to see more of them.
@appdev48613 роки тому
Yours is a much better video for newbies like me, than the other popular channels which actually just zoom past the descriptions. Your formula and circuit descriptions were very lucid. Thank u..
@PeterScargill6 років тому
I've been doing electronics for 50 odd years and how that simple trick evaded me I'll never know. Well presented.
@muhammadansnasir410Місяць тому
lol
@227218544 роки тому
Very intuitive explanation. You make excellent videos!! Please make more! One of the channels on UKposts that does make sense and is very educational down to the point you want. Lots of good examples and case scenarios.
@LiveMusicOntario5 років тому
Good stuff. I've seen a few of your videos like this one. You don't overload them with information the average hobbyist doesn't need, but you don't leave it so vague that a part timer might still get it wrong.
@gregcook99158 років тому
Thank you. You explained this really well! I like how you don't gloss over any of the important details and how you work up from a simple solution to a more complex one and explain all the hows and whys. Really excellent video!!
@nurhaida19837 років тому
amazing tutorial. thank you very much for the fine explanation. thoroughly clear
@FussyCashew12 років тому
Thanks man, I always learn something watching your vids
@MrRoyzalis11 років тому
Thanks for taking the extra time and effort to make your videos concise and succinct.
@thangbanben56835 років тому
You're born to be a teacher! The explanation is easy to follow
@djfahed30027 років тому
Thanks for the video. But when choosing the right MOSFET for some application, I think that the choice must also take in consideration the maximum current allowed through the transistor.
@engineerkohat5 років тому
Wow. It is something awesome and cool. Great work uploaded.
@joeelias25153 роки тому
This channel is a Carrier and by extension life saver,tons of credit to you Boss.
@ashley-dantesalmon81758 років тому
in a book i am reading, we just got from diodes to transistors and semitransistors and so i am glad to see this video from you. you can be a very great teacher for me to learn from
@ryanmcdougall747010 років тому
Please continue to make videos!
@Afrotechmods12 років тому
@mediaguardian Above -2V, (i.e. -1V, 0V, +2V etc.) the mosfet is in cutoff mode ("off"). Between -2V and -4V (specified min and max) the behaviour could easily vary from batch to batch and you could end up in the linear region where the Rds is several ohms to several kilohms. Then -4V or less (-5V, -6V etc) you enter saturation mode ("on") with lower resistance as you approach -25V. So in a switching application the designer knows to stay well beyond the -2...-4V range
@christopherweston60286 років тому
You do such a great job with the presentation: comprehensive and thorough.
@colt454712 років тому
@Afrotechmods that is exactly what I saw in the sim, and would expect. Thanks for the videos. Your time and effort making these videos are greatly appreciated. Thank you.
@jimviau3274 роки тому
Am I glad I stumbled on this tutorial! What a great trick. I never thought about that one. Furthermore, one could do the same with an N type MOSFET by just connecting the drain on the minus side of the power source.
@sony10703 роки тому
Hey man. The circuit in this video. Why does D and S revesed? Usually, PMosfet, S to + and D to load!!! This is crazy Plz help 😣
@jimviau3273 роки тому
sony10 , yes , I agree that at first glance, the circuit appear quite weird. But when you look closely pay attention to the polarity of a P channel Gate compare to Source. Keep in mind that a MOSFET is a variable resistor ( at least when utilized at low voltage ) . This means that , when ON, (short) , you can feed current both polarities, it still will act as a short circuit. This is why it appear weird when you look at a circuit that show a P channel connected as if it was a N channel. In this circuit the PMOS is utilized in reverse polarity. It need to be this way because of the internal inevitable substrate intrinsic diode that would be turned ON if you were to use an N channel and made a mistake of reversing polarity. You don't want any current circulating if in reverse battery connection. Hence, wether using a P or NMOS you want the internal diode in the direction of the current flow. Most circuits utilize a MOSFET configuration with current being blocked by the internal diode. In this circuit you want it configured such that when the battery polarity is correct the current would flow through the internal diode (if the gate was not energized) because in case of reverse battery polarity ( an undesirable error ) you certainly do not want any current flowing. So, you Then have to connect the PMOS in reverse, which is totally allowed according a MOSFET specification sheet. Once the battery is connected properly the internal diode will bring the Source to a higher potential then the Gate ( even if the Drain is of higher potential, it's not prohibited) you now have a Gate that could be connected to a voltage potential lower than the Source ( a condition to turn ON the PMOS) . Once the Gate is put to a lower potential it turns ON the PMOS and the voltage lost in the internal diode becomes almost zero because you now have a PMOS turned ON ( a short circuit ). Hope that make any sense to you. At least, that is how I see it.
@jimviau3273 роки тому
sony10 , the short version. A MOSFET can be utilized both polarities. As long as the Gate is at lower voltage then the Source you have a ON (short) MOSFET , which is what you want here in this circuit. D higher voltage than S is totally allowed if you do not exceed the forward internal diode maximum current mentioned in the specification sheet of your device.
@sony10703 роки тому
@@jimviau327 tks alot And tks again!!! Im thinking.... This one is crazy
@sony10703 роки тому
@@jimviau327 now I can die in peace ✌️
@ChupoCro6 років тому
Excellent explanation! There could be just one minor improvement - the contradiction proves the transistor cannot *stay* ON but it does *not* prove it wouldn't start to conduct from the initial state when it is still OFF. In other words, without proving the process of conducting could never *start* we cannot be sure if there aren't oscillations. Because, *if* in the initial moment the transistor was starting to conduct, we proved only it will turn OFF once after it *already* was turned ON. If the tranistor would then (when it is OFF) be able to start conducting (again) the process would repeat again and again. I am aware these conditional sentences are not grammatically 100% correct but I hope it could be understood what I wanted to say.
@akh3454 роки тому
If the battery is connected in reverse as in 3:21 then the Drain of PFET is below ground, then the Source pin doesn't have much chance of ever going above ground so PFET should never turn on.
@ocsee15 років тому
Thanks for covering the P-MOSFET VGS part as well. I corrected my design at the last moment. Thanks again.
@madhusudankumar58075 років тому
ONE of the BEST videos .Crisp and Clean.. Well done
@arthurchassande8333 роки тому
Very nice introduction to reverse battery protection technics. You also could have mentioned the use of NMOS (and its associated charge-pump circuit) if you are in the case of very high drain current (NMOS tends to have better Rdson characteristics than PMOS). But this method requires more complex circuitry of course ...
@andrewwhite179310 місяців тому
If your battery is isolated from 0V a N MOSFET on the negative works just as well😊
@HazeAnderson5 років тому
Honestly, the only thing I really understood was at the very very end when u said "You are now hereby granted with powers of reverse voltage protection!" 😬👍
@miketony20694 роки тому
I love coming to your channel and videos to "wrap up" my understanding of various topics. I'm newbie and just getting back into using p-channel mosfets. I had an ok understanding of how to read the p-channel data sheet to choose the correct transistor for my app however after listening to this it makes complete sense - I wish all my teachers were like you "back in the day" (or at least I wish they had youtube when I was in college lol) - thank you!
@jonathandiaz21424 роки тому
The world needs tons of people like you Sir....! very well detailed explained...! Thanks..!
@nRADRUS8 років тому
1. schematic called "ideal diode". 2. n-mosfet better then p-mosfet (cuz Ron is smaller). it have simmetrical schematic but inserted to ground wire . 3. nice video :) best regards
@DieBastler12348 років тому
+nRADRUS 2. True, but we want a common ground, if somehow possible. lg, couka
@ericcartmann7 років тому
Use a charge pump on the gate. Really simple to implement because its not drawing any current. You can buy a small IC that provides the voltage you need. To protect the charge pump IC you can just implement pMOS or a simple diode on its VCC terminal. Since it draws current in the uA range, the losses are negligible. The losses in implementing the charge pump to have a high side nMOS is usually much lower than using a pMOS
@robozstarrr89305 років тому
@@ericcartmann true but look at the datasheet again, it's spec'd at 0.026 ohms @ ~24 amps/10 volts, ( heat sunk to 25 deg C of course ) in any case at 2.0 amps it's much much less. personally i prefer Geranium diodes over Si... lower Voltage drop . . . & i have a ton of those laying around in metal cases.
@rich10514145 років тому
@@robozstarrr8930 The problem with those metal cases is they are made of zinc, and zinc whiskers. Most of them have already shorted themselves out and they are no longer manufactured.
@suzizecat5 років тому
Be _very_ careful about that on a complex system (with multiple boards, for example) because you may short the "Protected" Ground with the real ground over multiple boards and fry them all T.T
@TheTyrori4 роки тому
Afrotechmods come back, I miss how informative and easy to follow your videos are for learning. :(
@lazzatehayat3 роки тому
I am impressed by the clarity in your English and pronunciation.
@7c3c72602f7054696b3 роки тому
"...and you can be as drunk and irresponsible as you want." 😂
@nickpelov4 роки тому
Great video. It's much easier/cheaper to find low Rds on n-channel mosfet than p-channel. Once you get to
@DmitryAvsioukov4 роки тому
If you think of protective fet as of part of the battery, it doesn't make any difference, is it pfet at positive battery terminal, or a nfet at negative one. In other words, just assume your ground and positive rail after fet, and never think of reaching battery's terminals, and you are good. So I would think of using nfet at bottom always, they often go under 10 mOhm of rds on. Also, nfet is very convenient when you want to control its gate with a MCU for soft on-off feature.
@xkguy9 років тому
I'm just starting to study electronics and these are some of the most fun vids on YT.
@mschorer5 років тому
Awesome tutorial, very clear and definitely not a waste of time, like many others out there! Thanks a million!
@milanlukic17299 років тому
I know this works, but one thing is bugging me: if you are using a PMOS, the normal current flow should be from source to drain, and not the other way around. This should be OK if you had the symmetrical component (like JFET), but this is not the case. Can you explain this a bit?
@EastwoodTech8 років тому
Milan Lukic In fact, for PMOS, if Vds>0.7 or so, it just turn on and act as a diode (no matter what the voltage is on the Gate). you can get this info. from it's symbol...
@ElectroBOOM8 років тому
Milan Lukic MOSFETs generally work on the fact that a channel is created between drain and source when the gate charge attracts charges into the channel, reversing its behavior. When a channel is created, it doesn't matter which way the electrons flow in it.
@kbruin797 років тому
Milan, you’re right. The Drain-Source should be swaped. MOSFET has a internal diode that points from source to drain in N channel devices and drain to source in P channel devices. Therefore in a PMOS current flows from Source to drain not the other way around.
@123887536 років тому
ElectroBOOM Medhi! You are one of my heroes
@timonix25 років тому
@@SakarPudasaini10 you are a godsend
@perrychow129 років тому
Thanks for the great video, now I can make a more efficient killing machine. :-)
@abu0ibraheem6 років тому
One of the best videos that I have seen about electronics in a while Thanks
@freeelectron82614 роки тому
Very clever design and an excellent lecture on how it all works!
@Kabodanki9 років тому
"lol, typo" ha nice ^^
@LoganDark43574 роки тому
Still there
@megaman102512 років тому
Great I am a master at this...now I just have to learn electricity in physics...lolz
@peteleoni966511 місяців тому
You are simply an AWSOME teacher. Fantastic work! Thank You.
@46bovine4 роки тому
Great video, no god-awful background music (which is always too loud), or sound effects. Thanks Afrotech, you do good work.
@ashj_20884 роки тому
Yeah Bob you're right for once somebody mentioned something about the crappy generic music that people put on these electronic videos..thanks :)
@Antagon6668 років тому
I have the best and simpliest solution to this( without any wasted energy) Get yourself a some round connector, that you cant plug in reversed ! It's drunk proof, dumb proof...... :D
@AThreeDogNight6 років тому
That's funny. That is until I started to really thinking about it, it's not such a bad idea after all. If we made the whole world with drunk proof electricity then no more Boo Boo's with all of that going on No More, No More, as the Raven said, LOL.
@peerappel20124 роки тому
Poka yoke, always best indeed. Thought a protection can't do any harm...
@jeffbarney22612 роки тому
Until the drunk installs the batteries backwards.
@Arek_R.6 років тому
Mosfets are soo strange
@nsayer5 років тому
Think of a little guy inside with a voltmeter and a rheostat. The voltmeter measures the voltage between the gate and source. As that voltage increases, he turns the resistance down on the rheostat. It's the same as the model for a BJT, except that the little guy there has an ammeter instead of a voltmeter.
@KozisKey11 років тому
Please, please make more vids! I have learnt more from you than any other. You have ultimate teachers talent. Use it to fulfill child's dream of better world.
@Richardj4105 років тому
Thanks for this. I've been trying to figure this out and this video put all I have learn in place. Thanks for all the hard work.
@GalcoIndustrial10 років тому
Great video! I like how you were descriptive as possible, while creating an interesting video.
@4X10006 років тому
Afrotechmods, you are truly a master!
@princebanini8 місяців тому
this is incredibly helpful
@montyw470010 років тому
Excellent video & description of MOSFET usage especially the Rds value
@JYelton7 років тому
I can't for the life of me figure out how I only now discovered your channel... UKposts recommendations are lacking! I've been watching EEVBlog and W2AEW for years, but only found your channel recently.
@Flankymanga12 років тому
man your videos are allways awesome to watch! i really look forward to watch more from you!
@PreludeSon6 років тому
Why does people thumbs down on this video? This is very informative and useful information.
@AThreeDogNight6 років тому
Thank you very much, someone FINALLY!!! did a video on this. I've been looking for this particular answer for a week or two by now. First one was the SINE WAVE-MADE PURE was my first & of coarse the second one fell right into order with what I needed. I subscribed so hopefully I'll get any new ones on these subjects. Thanks again, Tom.
@Darieee5 років тому
I’ll be sure to include this neat trick into my next elerical projects, thanks !
@TT_R899 років тому
Amazing explanation, thanks for these tutorials!
@jeffowen32003 роки тому
that was so clearly and concisely explained, thank you so much!
@lykp12 років тому
@Afrotechmods Thank you very much! Yes, that was my mistake! And as a result I though that ground "had to" be something specific. I owe you one :P Everything crystal clear now! Keep up the great work with your videos!
@toms88183 роки тому
Excellent, easy to understand, very well designed presentation!
@137bob3d7 років тому
dazzling presentation. you're the electronics prof i never had. long line afrotechmods
@stevetobias48903 роки тому
Excellent solution, I was wondering about the wasted power of just using a diode. Thanks for a great answer at the right time
@CoolDudeClem12 років тому
This has made everything so clear, I have been trying to figure out p-channel mosfets for months now in a circuit simulator circuit simulator and getting really confused as to why things were not working the way I thought they would, and that's all because it doesn't show the ''parasitic diode'' in the mosfet.
@Moraffy079 років тому
Thanks man! you're videos are always solid!
@agaluszka7 років тому
what a gift to sell knowledge to others ! - world needs such teachers
@alanstarkie2001Рік тому
Handy to know tip! In certain cases where you're not bothered about power efficiency, just use a bridge rectifier then you can connect your power leads which ever way you like and it'll always work!
@dnvm843 місяці тому
Thank you for this video. I have watched numerous videos all talking about reverse polarity and showing you a generic circuit. But very few bother to comment on how to choose your parts. Again, thank you.
@DavyBoySmith9 років тому
Awesome explanation, we do this at work but many an engineer just take it as tribal knowledge, it is refreshing to have the principal explained as the teacher would explain it to the pupil.
@JasonKaler7 років тому
Thanks very much, I've been looking for this information for a while. It was very well explained, even for a beginner like me to understand.
@Afrotechmods12 років тому
@CoolDudeClem I implied several times in the video that if Vgs is 0V the FET would be off. It needs -4V or less to turn on. The circuit at the end of the video with the zener diode will clamp a large gate voltage down to the zener voltage.
@loverboy-if3ox6 років тому
love ur sense of humor. great vid too! I love to blow things up. ran 5v through a 3v led, lens cap got hot, exploded sending the cap through the ceiling tile AUSOME!!!!!!
@marioporras47237 років тому
Professional Solution: 1)Use of data-sheet parameters to support design. 2)Didactic video that explains clear and detailed. 3)focus only in topic. Great Tutorial.
@yurii.lompart3 роки тому
The greatest tutorial I have ever seen!
@9111logicРік тому
Finally the physical explanation I was looking for. Many Thanks🙏
@am_0x2a5 років тому
This is a wonderful tutorial! Bravo!
@brettschacher86443 роки тому
Very nice bit of info here. I always felt the simple diode (K) to input between B+ and a second diode also (K) to input from output, used for rev Pol. protection on Vreg IC's was suitable, still is of course since these are usually used in such low power circuits. However, since battery packs such as Lipo are now such a common supply for circuits, I really like knowing about this method. Now I need to put up a stock of P channel FET's and Zeners.
@alexcohen136911 років тому
Great tutorial, simple and very helpfull. Thank you.
@espenbgh25408 років тому
Keep on Afrotchmods you'r doing great.
@pfsupercars12 років тому
I love your sense of humor. Almost choked on my coffee watching this video, another great educational video.
@maxxsmaxx19016 років тому
This one is really good for me as I have just finished making my 0v to 27 v regulated discreet power supply with variable current . The lecture is very clear and precise.Very good video
@josephinespencer86216 років тому
Maxx Smaxx the zip
@lunarphotoduction10 років тому
this was great, gave me a clear understanding of the P-FET
@kubectlgetpo9 років тому
You are a really good instructor!
@spannerman48867 років тому
What a great teaching source! Thankyou👍
@v12alpine2 роки тому
I use this trick for all my portable projects. Excellent protection from the effects of alcohol.
@jamesallen60072 роки тому
Excellent in all aspects. You have more than earned my admiration, and subscription.
@JonathanAnon11 років тому
Brilliant videos.. practical, concise and clear... and love the bits of humour as well..
@L0j1k11 років тому
Your videos are awesome. I was watching a few of them trying to connect the dots for a simple reverse voltage protection circuit that doesn't have a big forward drop (I'm splitting the output from a computer power supply to try and power a few ultra-low-power boards from one). Then I saw this, which makes those leaps for me. AWESOME. Also, if you think there's any huge red flags I should watch out for in my project, please say something. :) Otherwise, keep making videos for the rest of time.
@matthiaskubisch2 роки тому
Love it. Great video. Saves my circuits for 4 years, or so :)
@paparoysworkshop7 років тому
Good demonstration. Nice clear voice that is easy to understand. Looking forward to more of your videos. You have a new subscriber.
@robertd1p212 років тому
Clear, concise and very thorough, what a great resource - no wonder you Teach! muchas gras. roBot
@Johnny8234512 років тому
This is an excellent video, I might incorporate a reverse polarity protection circuit into my next project
@zeroaviation7 років тому
Excellent video! Thank you! Look forward to more!
@pablom6952 роки тому
very concise, very to the point, very practical. love it. thanks
@YG3BMP-JZ13FLI4 роки тому
Thank you for the tutorial, it was very useful for me