What is the best Reverse Voltage Protection Circuit? || Repairing a Lab Bench Power Supply

[@ElectroBOOM]

I feel ... included! :D

[@RustieShackleFord]

ElectroBOOM where them free oscilloscopes at 👀

[@Guilherme_Parreira]

ElectroBOOM FUUULLLLBRIIIDGEEEETEKKTIFAIAAAAA

[@tesseract342]

so few seem to have seen this comment

[@johndah4x0r21]

Vodka + The smartest EE (electrical engineer) = *Bang!* [F--k! Sh--! What is this!? Ahh-F--k!]

[@BadMax02_VR]

so few saw it because the video was posted yesterday and only today he wrote a comment when the majority of the active subscribers have already watched the video

[@mircoheitmann]

remember kids, don't drink and charge

[@windshield11]

I bet that happens much more than you'd think. Especially if you're flying drones with the boys, then want to open some cold ones.

[@dj_paultuk7052]

Thanks, there will be a new EU law out next week now.

[@confusedwolf7157]

oooh harsh

[@paundra-lw1up]

Hahaha

[@gorillaau]

And be careful where you discharge... and never in a public place.

[@Kalvinjj]

That power supply has the weirdest heatsink I've ever seen and I love it

[@GrafRucola]

It’s so cool! BTW it’s common in other ELV LabPSUs as well :)

[@bretsutherlandsterriblemem8439]

Xbox One heatsinks are kinda strange too lol

[@daleburrell6273]

@@bretsutherlandsterriblemem8439 YOU BETCHER LIFESAVERS-!!!

[@ejezragaming2187]

Maybe the power supply gets hot quickly. So the big heat sink is used to make it cool. Why am I so nerd😂

[@mikeguy1899]

@@ejezragaming2187 very clever observation

[@paundra-lw1up]

If Tesla hired Electroboom... *car exploded* "NO REVERSE POLARITY PROTECTION, WHO DESIGN THIS SH*T?!"

[@prasana4047]

This cmt should go for 100 of likes

[@GRBtutorials]

At first I thought you meant Nikola Tesla and I was confused...

[@BruceNitroxpro]

paundra0217 , Really very funny because I don't own an electric car!

[@MohitSharmaxp]

Hi from 2021 Electroboom bought a Tesla

[@Splarkszter]

Same thought about the PSU on the video lmao

[@superdupergrover9857]

is it just me or is that the coolest looking heatsink? (1:33)

[@h3Xh3Xh3X]

It's either that or the most intense fleshlight...

[@pwnmeisterage]

Looks kinda mean. But also doesn't look very efficient, probably why it's an uncommon design, lol.

[@iblesbosuok]

Jealuosy

[@hariharanb785]

It'd nice if you could run a high static pressure fan sealed on that.

[@sebagomez4647]

It is indeed the coolest looking heatsink

[@ahndeux]

Scott always impresses me with his soldering skills. Amazing as always.

[@PelDaddy]

You might throw in a warning to test this out with a lower current battery rather than a high current SLA battery. A 12V SLA battery can easily dump enough current to fry decent sized wires and start fires. Don't ask me how I know. Always use a fuse with such batteries.

[@dwikey_98]

in fact, he used not only the fuse.. in the video, the fuse is not popped because the mosfet stays off while reverse voltage and current happens.. so the fuse only is not enough.. because the reverse voltage and current is already flows to the circuit before the fuse popped.. even the diode can blown up if that matter happens.. but many electronics has no fully proper reverse polarity protection.. fuse and diode can prevent this.. but, the diode can be very hot while reverse polarity happens.. and waste the power in form of heat, and even can blown up the diode if the voltages and current was too big.. so the fuse is the last defender.. and mostly the current surge was already flowing to the circuit with harmful amount of current before the fuse is blown.. and the electronics circuits may already broken if that happens.. so, the video is describing the whole point of this matters..

[@klong4128]

Very good scott ! I recalled 10 years ago when I taught industrial technicians/engineers ElectroPneumatics .The new laymen/greenHorn always causing 24v 10A power supply burnt. When I open out the CE or Industrial Professional power supply : The fast blown fuse never burn but others components burnt. Later I change the Fastest-fuse.Yet the same history happening .The last resort are buying two diodes lm4002. Same situation occuring.Finally I had to use lm4007 diodes, each connected inseries with + terminal and -terminal respectively. Good luck ,for more than ten years nothing Power Supply will ever burnt occuring !

[@TheHeretic2011]

The best reverse polarity safety is a full wave rectifier.

[@backdoornutzer4461]

*BRIDGE

[@Eratas1]

FUULLLLLLLLL...

[@satibel]

FOOOOOOOOOOOOOL BRIDGE RECTI-FIRE!

[@jayzo]

Although you might have issues with higher loads. I put reverse current protection diodes on an LED driver I build with a dual power supply to stop each supply trying to force current through the other supply in reverse and tried forcing 5A through it (current required by the LEDs). Despite being rated for 10A a LOT of smoke came out of them and they exceeded 100C by the time I'd noticed.

[@johndah4x0r21]

+ElectroBOOM FOOL BRIDGE REKTIFAIIA!

[@charyenne]

The same happened to my power supply, I wanted to charge a RC car race pack with 7.2 volts and the output of the supply was shorted. You and Electoboom helped me to repair it. The revers protection circuit in a labory power supply is like this, because it dont has any effect on the current and voltage output and vorsmall loads (inductive spikes, capacitors) this version is perfect. Its not made to protect against big current and voltages.

[@melissacoleman9633]

This is one of the best channels on KZbin and because I watch this channel my electronics ability has soared. Thx

[@greatscottlab]

Nice. Glad you like it.

[@ZenPanda2023]

Finally. We'll be able to see what's inside after so many long years and countless videos in attendance.

[@nautitard]

I see it was an easy repair this time, but I would love to see you reverse engineer things and general repair tips and tricks. Maybe this isn't your cup of tea, but if it is, it'd be very interesting. I got into electronics largely because I like transforming what other people see as waste, into useful resources again. I've spent many hundred hours in my garbage room, salvaging parts, working electronic gadgets and also repairing and giving away or selling cheap. Through your channel, I started building things from scratch, but I would also like to develop my repairing skills. So I'd love to see more of you, repairing things and describing the most common causes of modern electronic devices failing :)

[@TheRainHarvester]

Torgny Nordén I just fixed a cheap multimeter on video. It's so satisfying to repair trash.

[@manuel_elor]

X2

[@thesneakinspider3193]

I began watching you clueless to the technical side. Now with you and some other instruction I am beginning to grasp this

[@evgerven1]

Inspite your explanation, I would still go for the reversed diode but added with a (reachable!) fuse. As in a good PSU design, the sensewires should be connected as close as possible to the load. The fuse can be quite overdimensioned compared to the PSU maximum current as the PSU has its own short circuit protection.

[@tf3confirmedbuthv54]

Your videos got me into this kinda thing and ended up convincing me to get a career in electrical engineering. Thank you

[@BharatMohanty]

I guess this topic belongs to #electroboom 😀

[@omhekde]

Lol...

[@paundra-lw1up]

If Tesla hired Electroboom... *car exploded* "Damn, I put the electrolyte capacitor in the wrong way!"

[@BharatMohanty]

@@paundra-lw1up if Tesla hires electroboom he will electrify that factory's environment and that will be a shocking experience for all workers.

[@paundra-lw1up]

@@BharatMohanty LMAO

[@bkzzzzz]

yea with SHUNT and FULL BRIDGE :)

[@boblewis5558]

There is another use to which an FET switch maybe used to good effect (no pun intended) and that is where you have a backup battery connecting to a circuit powered normally by an external source e.g. mains derived supply and where you want the battery to take over instantly on input power failure such as a bulkhead emergency light, especially as where I have one - above the fuseboard! An N-Channel FET can be used so that while the input source is present no battery current is used and no reverse current is possible either. Once the mains supply drops, the light turns on. Quite often, in fact usually, such lights are ALWAYS on and the battery constantly on charge and it just takes over on power fail. Not always what is required. Another similar usage is when an external charging voltage/current is going to be used to deliver charge current via an internally fitted DC-DC converter. e.g. external charge voltage of say 16 volts via a buck converter providing a 12.6 volt charging voltage to a 3S battery pack. In such cases the output of the charger (DC-DC Buck converter) cannot be left connected permanently to the battery since it will be receiving reverse voltage from the battery when the device is switched off and no external charge voltage is present. Fitting a single N-Channel FET with its Gate tied LOW to ground via say a 10k resistor i.e. turning off the gate, BUT a second gate resistor of 100k is connected to the INPUT charge voltage point of the buck converter. The output of the buck converter connected to the Drain, and the Source to the battery to be charged. When the charge voltage is present and the device turned off, the FET will turn on provided the input voltage of the buck converter is such that the difference between it and the output voltage is higher than the FET gate threshold, the output turns on and starts charging. I have recently used this exact technique to replace the old NiMh cells with Liion cells of TWO Dustbuster hand held vacuums and fitted internal charge circuits to them instead that operate in exactly this way so that when they are off and placed in their charge cradles (which can now be powered by ANY convenient 16-35 volt DC supply) they charge fine. As soon as they are unplugged the FET switches off and prevents the battery from reverse connection to the output of the buck converter which would otherwise drain the battery and also turn on the converter's output LED via the back-fed current!! This works GREAT. Especially as all the components needed were recovered from motherboards and suchlike! I included a BMS of course but also a battery status display with a button to manually show the state of charge when required but also it's auto switched by another FET when connected to the charge power.

[@m4gmu5hell]

Wow. Very nice to see a new GreatScott video on Friday ^^ I actually destroied a power supply at work also by connecting a big 12V Lead acid battery the wrong way around. Should have used this circuit ^^ Thanks for the advice!

[@renatoturkovic4299]

How Friday?Its uploaded on sunday!10 minutes ago!How is this comment old 2 days?ARE YOU TIME TRAVELING!!!

[@luongmaihunggia]

*destroyed

[@m4gmu5hell]

@@renatoturkovic4299 Patreon ma boiis ^^

[@ahmedsiddiqui9515]

How your comment is 2 days old ?

[@m4gmu5hell]

@@ahmedsiddiqui9515 Patreon ma boii ^^

[@FantaBH]

At first was thinking same video as many before but after watching you came to problem well known to me and as well finally someone who made video complete by showing right circuit at the end which will protect power supply on right way.

[@eformance]

Doesn't the cut-in voltage of the MOSFET limit the minimum voltage you can output from the power supply? It would seem to me that a virtual zener that drives a N channel MOSFET, via a proper driver chip, would be another solution with fewer drawbacks. N-channel MOSFETs tend to have a lower resistance too.

[@hqiu6828]

Just made the same mistake and blew my small 30V DC-DC module. I will try this Reverse Voltage Protection method. Many thanks!

[@dawnminilla9299]

the circuit you found is a poor solution because after it is used once you have to remove the gate charge as the fet will stay conducting and when you try to hook a battery backwards it will be a short for a moment until the gate capacitance is discharged and the current can well exceed the maximum allowed by the fet. This generally will not fail right away but it does as I've built this exact circuit years ago for a charger we use at work and they fail about every 6 to 8 months. After an exhaustive look into the failure mechanism this is what I found. I measured sharp spikes in the 1000's amps using an irl60b216 once conducting and hooked up in reverse to a car battery

[@hannes7893]

hey that's such a coincidence. I did the same a week ago and now am able to repair mine as well, thanks a lot

[@ugetridofit]

There are circuits that use a relay in line with the load. The coil is driven by a circuit that detects very low reverse voltage and opens the relay.

[@monkeymanstones1]

I always check each and every connection with my multimeter before plugging power in and I check the battery terminals for current directivity before plugging anything in. Quick, easy and as safe as you can hope for (unless you're wearing jewelry - Example if you have a ratchet/socket in your Right hand and touch your socket to either terminal and don't realize you're touching your Left hand's wedding ring to the other terminal you instantly die as the power moves straight across your heart [it's right between your 2 arms & hands!] but good luck convincing anyone to remove their wedding rings when doing such work!).

[@Shocker99]

7:45 This isn't a new design. I've seen this circuit 15+ years ago. Depending on how you design it, it can also double a basic step down regulator.

[@zeljkovelikipopovic]

Hvala Vam puno na korisnim savetima na vašem kanalu. Thank you very much for the helpful tips on your channel.

[@vedant3321]

You mentioned electroboom finally 😍

[@junuhunuproductions]

GREAT video! It was a little tricky to understand why fuse kept blowing & mosfet kept conducting currents when reverse-battery-voltage was applied, but all in all, great!

[@rich1051414]

Why use a silicone solution when you can use a relay for reverse voltage protection? Pricey, but you get no voltage drop, no heat generation. It surprises me how so few people show using a relay to make a truly ideal diode.

[@tannimkyraxx]

Failing to add some reverse polarity protection to my bitx40 ham radio, and subsequently figuring out how to stuff all the magic smoke inside sucked, but actually advanced my skills quite a bit.

[@kardeef33317]

I don't know if its just me, but the whole video from start to finish seemed like it was running 10% faster then normal. Awesome video and thanks again for sharing your knowledge.

[@packratswhatif.3990]

Haha, been there - none it (blowing up my power supply). But you do have to love the power mosfet versions ! Just build it into your power supply and change the point where your power supply monitors the output voltage to the output of the mosfet protection circuit.

[@pauljackson2126]

What if I add a FULL BRIDGE REKTIFIYAA.......?

[@S1278-q9f]

FOOL BRIDGE*

[@sonicunleashedfan124]

God dammit

[@caua737]

Electroboom hahahaha

[@MrBobman49]

Zen you vill haf 1.4V drop across it and you missed the point.

[@josefaschwanden1502]

Voltage drop, but it would work

[@kwazar6725]

When charging batteries use a proper charger. My icharger detects all sorts of misconfigurations and as scotty said prevents fire..... you can get ics spevially made for a multitude of reverse current reverse polarity short cct and more.....

[@kwazar6725]

Scott . Maybe build an external all singing and dancing super protector with meters and leds. Maybe use the ltc devices or whatever...

[@GRBtutorials]

And that's what "ideal diodes" are made of.

[@Jindraxx20]

Thank you Scot for this content. It was very interesting the part regarding voltage vs current source protection.

[@runforitman]

No power supplies were harmed during the making of this video

[@brunobastos5533]

Fuses is probably another story

[@freevbucks8019]

Actually 1 power supply was repaired

[@sylkelster]

I have noticed an inverse relationship in bench power supplies between Chinesium and on-board circuit protection, with high accuracy.

[@petzi8695]

Make a tube amplifier

[@Krunalbhongade]

The diode in parallel is added generally to damp transient voltages which might happen during inductive loads... This parallel diode also happens to act as a reverse polarity protection. That parallel diode might be a TVS or a schottky diode.

[@ponchov.9116]

"It is bastards" - 0:38 (Enable automatic subtitles)

[@BjornV78]

7:47 I think this is the type of protection that is used in modern commercial car batterychargers (trickle loader), they don't charge when the battery is below a certain voltage, and the + and - outputs are shortcircuit protected, because they don't carry a voltage when there is no battery connected.

[@sergeantseven4240]

This is probably why using a lab power supply to charge a battery is not recommended. Battery charging circuits have protections built in for this reason.

[@GrulbGL]

Yeah... just a diode in series, than compensate the voltage...

[@arphyl2815]

Quick question: Why not use an H-bridge config at the output rails? To make sure that the + and - rails remains as is. We used that in our project. 🤔 Although I see that the power efficiency and voltage drops will be some considerations.

[@rafgaming709]

Make a tube amp please! I know it is easier with solid state stuff but transistors will never beat the warm sound of tubes!

[@nerfinator03]

Lel

[@chrismofer]

you could put a latching relay and diode to have close to no voltage loss and still a fiarly fast decoupling on reverse voltages

[@doufasmilz485]

Can you do an ups?

[@JBPerformanceTV]

Up

[@tameralsebaee1433]

Thanks for video We can use a relay with a diode to protect from wrong polarity without voltage drop But must use same voltage for relay coil and for the load

[@lbgstzockt8493]

this system wouldnt be as bad if the diode could be swapped more easily

[@slrn832472577]

Maybe mounting a perf board on the back of the power supply that contains the diode on the outside of the power supply for ease of replacement.

[@davey2k12]

Could protect diode with a heavy latch relay on a separate power source disconnect the output when polarity is reversed or shorted

[@johnfrancisdoe1563]

Eric Daniels Just put the diode in a fuse holder. But encouraging internal repair of lab equipment is good outside the calibration industry.

[@davidjames1684]

I was testing 2 different 13.8V power supplies to pump up an air mattress and by accident, I forgot to disconnect one of them while energizing the other that was also connected, I guess it didn't like backfeeding power that way as it damage BOTH of the power supplies. Do you think I should try a similar fix (replace diodes) as you illustrated here?

[@QLTD]

I prefer sticking with the original method to get accurate voltage also mistakes happen once I don't think I will blow the diode again in the future 🙂

[@Detonador7G]

Hey, I might be a bit late but at 5:27 the mosfet in ON so the diode is shortened, and therefore you don't have that 1.3V drop.

[@Asu01]

Pfft, reverse polarity protection is only for the weak.

[@MCsCreations]

😂

[@HobkinBoi]

Yep. Once you blow something up, you almost always remember to make sure you set up correctly.

[@BadMax02_VR]

if you work at a atomreactor you also dont a second chance yo make sure to always connect correctly or just thing that your city will blow up xD

[@domino52o26]

@@BadMax02_VR Technically not true but it was good humor. 7/10

[@confusedwolf7157]

quick...lets get to the chopper

[@fredrickrari9338]

Would it be advisable to put a full bidge rectifier at the power input terminal so you wouldnt care too much which lead goes where?

[@Mrugendraa]

Best way for Reverse Voltage protection is DO NOT MESS WITH ELECTRONICS WHILE YOU R DRUNKED...!!! ;P ●●●●●●●●●●●●●●●●●●●●●●●

[@freevbucks8019]

no shit sherlock

[@Samuel-km5yf]

This is great! I just permanently modified my power supply by putting one of these circuits inside it. Now I’ll never have to worry about connecting it in reverse again!

[@johnavonvincentius1884]

What kind of power supply is it? What is the Max Voltage,Current and power.

[@greatscottlab]

ELV DPS5315 0-30V 0-3A

[@nigeljohnson9820]

Some power supplies do not like power being supplied from the battery when the power supply is off. The old kings hill bench power supplies were damaged if the power supply was turned off with the battery still connected. My colleagues and I discovered this when the lab earth leakage circuit breaker was tripped while charging some lead acid batteries. I would be interested to know if your PSU suffers the same problem. As I recall the fault was the result of latch up in the voltage control op amp circuit when mains supply was restored with the battery still connected. As far as I can tell the MOSFET circuit does not resolve this problem, as current can flow through the intrinsic reverse diode between drain and source. In the preferred circuit, would it have not been better to run the driver transistor as an emitter follower to limit the MOSFET gate voltage to Vz-vbe..

[@paundra-lw1up]

Ft. Electroboom

[@xyzxyz-y1b]

you can use a simple full bridge rectifier

[@mattv9989]

uploaded 52 seconds ago, a comment from 2 days ago..........

[@greatscottlab]

Patreon supporters can watch earlier.

[@mattv9989]

oh that makes much more sense :D

[@beedslolkuntus2070]

@@greatscottlab Do you have patrons plans like rewards electroboom has 6 reward types....

[@Dust599]

the privilege of wealth...

[@confusedwolf7157]

that...is...sooooo specific

[@mupschiplayz1802]

FINALLY a new video from Scott

[@greatscottlab]

Every Sunday ;-)

[@mupschiplayz1802]

Hey GreatScott, Could you give me the Amazon Link with i can support you?

[@renatoturkovic4299]

I never had problem with reverse voltage

[@danfishermen5362]

I had

[@RyutakuZaki]

1) you are starting with electronics 2) you’re a liar

[@andrewkieran8942]

There only two kinds of electronics hobbyists, those that have done this and those that will.

[@roygalaasen]

Until one day you had a problem with reverse voltage.

[@renatoturkovic4299]

@@RyutakuZaki Every time when I make circuit I always double check or triple check circuit for reverse polarity supply or capacitors

[@JensHeuschkel]

Is there a IC available for the circuit shown last ?

[@beedslolkuntus2070]

someone say hi to me.... Hi you person reading the comments!! have a good day

[@MRA_3]

Hello,how are you ?

[@satibel]

hi to me....

[@araigumakiruno]

hi from malaysia

[@sam_8a]

hi to me

[@dalenassar9152]

Greetings and salutations from way down south in Amite, Louisiana. Where are you?

[@intheshell35ify]

"Horrible, inefficient, and useless" But tell us, how do you really feel?!? Love it.

[@gonun69]

Didn't watch the video yet. But... FULL BRIDGE RECTIFIER!

[@hedgehogthesonic3181]

And what is a *FULL BRIDGE RECTIFIER!* ?!?!?!?!?!?!?! I know it have some capacitors and stuffs but the function of it is unknown for me...

[@DFX2KX]

@@hedgehogthesonic3181 It's an arrangement of diodes that turns A/C current (which goes back and forth both ways) into DC current. It's not efficient however.

[@hedgehogthesonic3181]

@@DFX2KX DC only moves in one direction right ?

[@xero110]

With this added information I’ll be making my own bench top power supply. Great video, thanks.

[@DrHarryT]

"What is the best Reverse Voltage Protection Circuit?" As it has been for years...A diode and a fuse.

[@BHAVYAMATHURBEE]

Amazing video man! However you should have gone with the N-Channel MOSFET. N-Channel MOSFETs are generally way more cheaper, has a lower Rds(on) and gate junction capacitance. Means its cheap and power efficient. Keep making these videos man. I'm totally a fan. And I will see you next time!

[@rhogan88]

NFETs are better when it comes to low RDSon values because they are better carrier mobility. ~3 for the same given area. PFETs will also work but if we are optimizing...

[@UndercoverFerret404]

Shouldn't the fuse be on the other side of the diode? So it interrupts mistakes like yours, when you're trying to feed into the power supply.

[@bjl1000]

I can't believe you spent almost 9 minutes on this!

[@magicianofelectronics951]

I have destroyed one of my boost converter(bought after seeing on your channel), by connecting 3.7V 18650 battery in reverse, that is why I'm here, but in my case, diode will be good as I want to operate a solenoid mechanism for approximate 2 seconds, thank you

[@RyutakuZaki]

From the beginning Hehe I knew that you got inspired by electro boom. My two favorite channels :D

[@kepi765]

Genau mir ist auch leider der selbe Fehler passiert, aber gut dass es GreatScott gibt!

[@RichardEricCollins]

So why don't bench power supplies have this built in? Seems to be a cheap addition?

[@KerbalLauncher]

What about using an ideal diode driver and nchannel mosfet, pchannel mosfet electrical characteristics are inferior and costly in the higher performance ranges.

[@claudiu7909]

5:20 doesn't P mosfet act like a normal diode in this case? Since the drain voltage is higher than the source voltage the diode conducts. If I'm not mistaken, the P channel mosfet conducts from S to D when it's on. So even if the voltage of the battery (10.7 V) should turn on the transistor, it's useless as the current cannot travel from the PSU to the battery through it, only through the diode. If you connect the PSU in reverse, the Vgs would still be negative (because of the battery) and the mosfet will conduct, in other words it won't solve the reverse voltage problem. Also, if you connect the battery in reverse, the Vgs will be positive and the transistor off, but the diode will since the source will have a lower voltage than the drain. So, you still have a reverse voltge problem. So the P mos alone is not a solution at all.

[@Albert-fe1xn]

I almost watched all of your videos, Not knowing Im not yet subscribe, and Now I subscribed that's why I made a Comment. HAHAHA. GREAT VIDEOS VERY INFORMATIVE AND HELPFUL. WATCHING FROM THE PHILIPPINES 😂

[@UBsLab]

Which was the fuse you used over there? Please specify

[@InFAMOUSPS4_19]

When are we going to see a collaboration video between these 2? I know the distance is pretty great but still something I'd love to see in the future.

[@y2ksw1]

I have used a microprocessor and a reed switch for protection. This way, the voltage and current from the lab supply remains unaltered.

[@TheRainHarvester]

y2ksw1 how quickly does it react? I was thinking the same thing.

[@y2ksw1]

@@TheRainHarvester Small reed relays can switch much faster than a half period of 50-60 Hz, thus "instantly" as we look and feel.

[@МаксимГрищенко-н1с]

An IRL5602S transistor can be used to protect a circuit with low power - 3.8 - 5 volts. It opens completely from the logic level of the signal (2-4 volts).

[@nassimkoubeissi5814]

Great tutorial You can use a thyristor with a relay When a reverse voltage detected by thyrisyor it triggers the relay and opens its switch note to use a Fast acting relay .

[@freddymercury8556]

Coincidence......that happened to me a week ago as well. Feels like God answer my prayers!

[@Kaspar_NL]

Really great vid to show the 'flaw' of the design of your power supply including a fix!

[@peterdkay]

Interesting solution but it needs a battery connected to turn P-MOSFET on. So it will not work with passive loads. Maybe a 100k resistor from supply (+) to base of NPN to turn it ON with passive load. Any reverse connected battery will still switch NPN off.

[@hrishikeshgawas4579]

Hey nice video. I want to protect my power supply from reverse voltage when i am charging my batteries. I dont want to make a circuit and stick to adding a diode. Now I am not an electronic engineer so sorry in advance if I made a mistake but what I found for 1N5822 is max rectified forward current is 3A so it means that max curent that can go through it is 3A but my power supply delivers upto 8A so can I add 3 diodes in parallel?

[@lazal3m]

Will this reverse voltage protection circuitry affect the voltage and current readings when using on load?

[@cbcdesign001]

Yes it will affect the voltage regulation due to the drain to source resistance in the mosfet. A fuse to protect the diode is the simplest way to protect the PSU without affecting the voltage regulation.

[@lazal3m]

If the PSU can supply 10A, what amp rating of fuse would be optimal as reverse protection?

[@solewalk]

8:04 there seems to be a problem with the circuit. If the battery to be charged is totally discharged, it won't be able to turn on the BJT transistor which is supposed to control the mosfet.

[@sudipbabudhakal7236]

We can use bridge rectifier as well, if drop of 2*0.7 voltage is acceptable with some power loss as well. Afterall device is protected as well, We can power up with any type of connection, either reverse or forward, and it work flawlessly for small power circuit.

[@Loundre3]

Or using something like this: www.ti.com/tool/tida-00858?keyMatch=smart%20bridge%20rectifier&tisearch=Search-EN-Everything

[@noweare1]

Loundre3 Nice, thanks for that.

[@agstechnicalsupport]

Thank you for posting such an instructive and practical video on reverse voltage protection circuits !

[@brunobastos5533]

Allways be safe use protection

[@nasimakhanam2445]

This is really a useful video

[@ronc1357]

Hello Great Scott: I don't know if this would interest you... I have an idea for a project for you... I am working on a wired remote control mini pontoon boat (wired so if something goes wrong I won't have to go swimming for it). What I want to do is make an ultrasound depth finder on it with an LCD display... It will all be controlled with an Arduion uno... The purpose for this is for fishing I would like to be able to drive the boat to where I intend to cast my line, and find the depth.

[@alaattincabuk4764]

Does this work for back emf on a brushed dc motor.

[@ShomiTheGreat]

Back to jlcpcb advertising. Cool.

[@somedude2492]

And what about a diode in parallel which then has a fuse, so when reverse polarity is applied, current flows though the diode, then the fuse to close the circuit, the fuse blows up and cuts any connection from the psu to the battery? I see no drawbacks other than the fact that you have something blowing up that will need to be replaced every time you fuck it up.