Duration 6:46

How to protect circuits from reversed voltage polarity

by Afrotechmods

2 136 986 watched

37.1 K

Published 2 Dec 2011

How to use diodes, schottky diodes and P-FETs to protect your circuits from reversed voltage/power connections. Website: http://www.afrotechmods.com/

Tags

Tutorial

Electronics

Electric

Circuit

P-FET

MOSFET

Diode

Protection

P-channel

Semiconductor

Voltage

Polarity

Field-effect Transistor

Comments - 1062

@

@Afrotechmods7 years ago 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 "YOUTUBE"
.. ...Expand 65
@

@universalsailor10 years ago This series is excellent. Easily the best electronics tutorials on youtube that i' ve run across. Someone please give this man an award. 115
@

@PeterScargill7 years ago I' ve been doing electronics for 50 odd years and how that simple trick evaded me i' ll never know. Well presented. 8
@

@Escatrax10 years ago 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. 439
@

@DeadKoby8 years ago 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 . ...Expand 2
@

@georgekot63778 years ago Just wanted to say you make the best tutorials! 160
@

@jomac_ph5 months ago 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. 1
@

@227218545 years ago Very intuitive explanation. You make excellent videos! Please make more! One of the channels on youtube that does make sense and is very educational down to the point you want. Lots of good examples and case scenarios. 4
@

@lazzatehayat3 years ago I am impressed by the clarity in your english and pronunciation.
@

@thangbanben56836 years ago You' re born to be a teacher! The explanation is easy to follow.
@

@appdev48614 years ago 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.
@

@str0g13 years ago 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 . ...Expand 1
@

@LiveMusicOntario5 years ago 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 . ...Expand 1
@

@silasfatchett56938 years ago Just as your other videos, a clear and concise explanation of an electronics concept. Thank you. 4
@

@joeelias25154 years ago This channel is a carrier and by extension life saver, tons of credit to you boss.
@

@46bovine5 years ago Great video, no god-awful background music (which is always too loud) or sound effects. Thanks afrotech, you do good work. 2
@

@ashley-dantesalmon81758 years ago In a book i am reading, we just got from diodes to transistors andand so i am glad to see this video from you. You can be a very great teacher for me to learn from. 1
@

@TheTyrori4 years ago Afrotechmods come back, i miss how informative and easy to follow your videos are for learning.
@

@jonathandiaz21424 years ago The world needs tons of people like you sir.
very well detailed explained.
thanks. 2
@

@JYelton7 years ago I can' t for the life of me figure out how i only now discovered your channel. Youtubeare lacking! I' ve been watching eevblog and w2aew for years, but only found your channel recently.
@

@dnvm844 months ago 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.
@

@PreludeSon7 years ago Why does people thumbs down on this video? This is very informative and useful information. 1
@

@gregcook99158 years ago Thank you. You explained this really well! I like how you don' t gloss over any of the important details and how youwork up from a simple solution to . ...Expand 1
@

@xkguy9 years ago I' m just starting to study electronics and these are some of the most fun vids on yt.
@

@FussyCashew13 years ago Thanks man, i always learn something watching your vids. 3
@

@peteleoni966511 months ago You are simply an awsome teacher. Fantastic work! Thank you. 1
@

@MrRoyzalis11 years ago Thanks for taking the extra time and effort to make your videos concise and succinct.
@

@miketony20695 years ago 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 . ...Expand
@

@KozisKey11 years ago 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.
@

@colt454713 years ago @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.
@

@jimviau3275 years ago 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. 6
@

@christopherweston60287 years ago You do such a great job with the presentation: comprehensive and thorough.
@

@agaluszka7 years ago What a gift to sell knowledge to others! World needs such teachers.
@

@marioporras47237 years ago 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.
@

@CoolDudeClem13 years ago 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 . ...Expand
@

@madhusudankumar58075 years ago One of the best videos. Crisp and clean. Well done. 1
@

@arthurchassande8333 years ago Very nice introduction to reverse battery protection technics. You also could have mentioned the use of nmos (and its associated charge-pump circuit) if . ...Expand 7
@

@ocsee16 years ago Thanks for covering the p-mosfet vgs part as well. I corrected my design at the last moment. Thanks again.
@

@abu0ibraheem7 years ago One of the best videos that i have seen about electronics in a while
thanks.
@

@AThreeDogNight7 years ago 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 . ...Expand
@

@alanstarkie20012 years ago 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! 1
@

@9111logiclast year Finally the physical explanation i was looking for. Many thanks.
@

@ChupoCro6 years ago Excellent explanation! There could be just one minor improvement - the contradiction proves the transistor cannot stayon but it does not id="hidden22" 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 startwe cannot be sure if there aren' t oscillations. Because, ifin the initial moment the transistor was starting to conduct, we proved only it will turn off once after it alreadywas 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. ...Expand 18
@

@137bob3d7 years ago Dazzling presentation. You' re the electronics prof i never had. Long line afrotechmods.
@

@maxxsmaxx19017 years ago 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.
@

@mschorer5 years ago Awesome tutorial, very clear and definitely not a waste of time, like many others out there! Thanks a million! 2
@

@gotj3 months ago Y aqu estoy yo 12 aos despus, disfrutando de este maravilloso vdeo por segunda vez. Es una lstima que este canal est tan parado.
@

@engineerkohat6 years ago Wow. It is something awesome and cool. Great work uploaded. 4
@

@loverboy-if3ox6 years ago 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! 1
@

@paparoysworkshop8 years ago Good demonstration. Nice clear voice that is easy to understand. Looking forward to more of your videos. You have a new subscriber.
@

@llewgnal13 years ago Some of the finest tutorials on youtube, thanx.
@

@freeelectron82615 years ago Very clever design and an excellent lecture on how it all works!
@

@stevetobias48904 years ago Excellent solution, i was wondering about the wasted power of just using a diode. Thanks for a great answer at the right time.
@

@nurhaida19838 years ago Amazing tutorial. Thank you very much for the fine explanation. Thoroughly clear. 5
@

@yurii.lompart4 years ago The greatest tutorial i have ever seen!
@

@pfsupercars13 years ago I love your sense of humor. Almost choked on my coffee watching this video, another great educational video.
@

@woutdezeeuw16042 years ago Man, i' m just seeing this wondering how to do this earlier today, and i already sent out my pcb design for manufacturing! Such timing.
@

@v12alpine3 years ago I use this trick for all my portable projects. Excellent protection from the effects of alcohol.
@

@jessstuart74953 years ago Very nice explanation. I teach electronics at a local community college, and i will definitely suggest your youtube channel to my students.
@

@djfahed30028 years ago 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. 7
@

@JonathanAnon12 years ago Brilliant videos. Practical, concise and clear. And love the bits of humour as well.
@

@Flankymanga13 years ago Man your videos are allways awesome to watch! I really look forward to watch more from you!
@

@L0j1k11 years ago 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 . ...Expand 1
@

@espenbgh25409 years ago Keep on afrotchmods you' r doing great.
@

@montyw470010 years ago Excellent video & description of mosfet usage especially the rds value.
@

@HazeAnderson5 years ago Honestly, the only thing i really understood was at the very end when u said " you are now hereby granted with powers of reverse voltage. 8
@

@richardmoz5 years ago 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.
@

@jamesallen60073 years ago Excellent in all aspects. You have more than earned my admiration, and subscription. 1
@

@lykp13 years ago @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 . ...Expand
@

@MeridianOfficial4 years ago Super hard to find information oh how to use a diode but this was very clear and helpful and i finally understand what it does.
@

@GREGGRCO10 years ago Thank you. Clear. Exactly what we were talking about at breakfast; and you' ve already done it!
i was using this in solar panel design eliminating looking at n channel for lower rdss. Nice tutorial, thanks again. ...Expand
@

@Afrotechmods13 years ago @mediaguardian above -2v, i. E. 1v, 0v, +2v etc. The mosfet is in cutoff modebetween -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 modewith lower resistance as you approach -25v. So in a switching application the designer knows to stay well beyond the -2. 4v range. ...Expand 7
@

@toms88183 years ago Excellent, easy to understand, very well designed presentation!
@

@DavyBoySmith9 years ago 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.
@

@toastonryeYT3 years ago Great video, came up on my page 9 years later!
@

@GalcoIndustrial11 years ago Great video! I like how you were descriptive as possible, while creating an interesting video.
@

@matthiaskubisch3 years ago Love it. Great video. Saves my circuits for 4 years, or so:
@

@7c3c72602f7054696b4 years ago " and you can be as drunk and irresponsible as you want. " 5
@

@shyamramnani63134 years ago Very good video. Everything explained was to the point. You must be the expert in electronics. Thanks.
@

@JasonKaler8 years ago 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. 1
@

@levitronics72899 years ago Dude, you re great. Am new to your channel but never too late to be a subscriber. Great contents out there. Thumbs up to.
@

@Moraffy0710 years ago Thanks man! You' re videos are always solid!
@

@lunarphotoduction10 years ago This was great, gave me a clear understanding of the p-fet.
@

@nRADRUS9 years ago 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. 11
@

@jeffowen32004 years ago That was so clearly and concisely explained, thank you so much!
@

@csaracho20094 years ago Thanks for this excellent video. By the way, i would like to point out that, in my perspective, that is not an impossible contradiction, but only a contradiction.
@

@takashiyumita12573 years ago There is also a way to connect a diode in parallel with the load, but this will damage the power supply.
the method shown is apractical circuit.
@

@brettschacher86443 years ago 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. . ...Expand
@

@nickpelov5 years ago Great video. It' s much easier/cheaper to find low rds on n-channel mosfet than p-channel. Once you get to < 50mohm the difference in becomes quite a lot. So if you don' t care if the battery minus gets few mv above ground you could use n-channel. Of cource if you need accurate battery voltage it' s much easier to measure when the battery minus is at ground level. ...Expand 4
@

@Johnny8234513 years ago This is an excellent video, i might incorporate a reverse polarity protection circuit into my next project.
@

@robertd1p213 years ago Clear, concise and very thorough, what a great resource no wonder you teach! Muchas gras. Robot.
@

@Darieee6 years ago Ill be sure to include this neat trick into my next elerical projects, thanks!
@

@PSPS43711 years ago In p-channel. Load is always connected to source. When gate is pulled down to ground, the current flows from source and passes through the drain into id="hidden38" the load. Mosfet is bi directional. Your video is trying to tell the opposite way if i am not wrong. Your explanation is pretty good. @ 2: 39 if the mosfet is on, then body diode turns off. @ 2: 39 both are conducting which is a big flaw. Body diode is on when the fet is off. I am just trying to explain it. Your videos are awesome. ...Expand
@

@georgekurgansky59863 years ago Woaahh! If only this was the level of quality on solar forums!
@

@pirateman19667 years ago Damn, that was the clearest i have ever seen! You are awesome. Sub' d for sure. +1. 1
@

@moeshouse5755 years ago Being an electronics newbee, i really enjoyed that, thanks.
@

@oxiigen13 years ago This tutorials are really fantastic! Simple, clean and efficient. Thank you!