I just want to draw attention to how perfectly you explain the design methodology. Every step highlights a solution, and resulting problems. Rinse, repeat. This makes an otherwise daunting looking circuit, really just look like 4 or 5 small very straightforward circuits stuck together. Legend.
What the hell, literally less than 20 hours ago I was scouring the internet for a good guide to short circuit protection. GreatScott couldn't be more perfect.
This is EXACTLY what I was looking for and you even addressed the infinite loop question I had. I haven't done electronics in 10+ years and my brother wanted me to make him something. Turns out I've forgotten everything and it was very daunting till I came across your channel. Thank you very much!
Wow, dude... I understood that whole schematic as you described it -- that's like the most complicated schematic I think I've ever been able to understand! -- You did really well breaking out each component and explaining it separately. -- Thanks, man! :-)
Yes, I most certainly enjoyed the video. A year from now I'll be able to design my own circuits thanks to your instruction. I'll just toss in a comparator over here to turn that off; ... right off the top of my head. Thanks, I watch your videos almost daily.
The problem that I foresee is that with a 12V supply, the inputs of the first LM358 are sitting at around 11.4V. Unfortunately, the LM358 has a specified common mode range of only up to Vcc - 1.5V which would be 10.5V with that supply. Now, you may be lucky and find that the opamp works with its inputs at 11.4V, but it's not guaranteed. The inputs are PNP Darlington transistors with a current source in the emitters and just can't operate very close to the positive rail. Worse is if you use a lower voltage supply like 5V, when the opamp's inputs would be at 4.76V with a maximum common mode range of only up to 3.5V. The behaviour would be quite uncertain in that sort of case. The simplest solution is to monitor the current low-side. That is, you put the current sense resistor in the negative line, which is a common approach. Then the inputs are close to ground, but that doesn't matter because the LM358 (and many similar opamps) include the negative rail in their common mode range, so are guaranteed to perform as expected.
I love the videos Scott! I had to mention though that you can get short circuit protection and more all in one IC. Texas Instruments tps2h160 is a 2 channel high side switch with short, reverse, current limiting and temperature protections. Simply set the current limit with a single resistor and send logic level from your favorite mcu to the inputs. As of March 2020, it's a whopping $1.63 US.
the last bit about using a fix resistor i believe if the supply voltage changes it will still effect a resistor unlike some zener or regulator please correct me if i am wrong
Thomas Cruz LM4040. Somebody is playing with the good stuff.... The challenge for this circuit is the need for an extra reference voltage. For the scavengers and poor boys like myself, a simple TL431 will work. They can be found on almost every AC to DC switching type power supply made for consumer goods :-)
Nice work. You could have connected the opamp power to the relay output to get a cut off latch. The second relay can be eliminated. For the reference voltage, you can use a 4007.
For even more simplicity, you can use a single channel power switch IC to provide a fixed voltage overcurrent and reverse current protection. For 500mA or 1A, I recommend the STMPS21X1.
I liked the video right away, this is a very nice project although, in my opinion, it ended up being a little too big for its purpose. But it is a very nice introduction on this topic and could be used to compare with a purpose built IC, like the LTC436x series.
yeah there's purpose built IC almost for everything now! But well this is a cool _weekend project_ that some might be able to built with parts that already they have.... and a good middle level electronics to learn from! (which makes a good TH-cam content... I'm an electronic engineer and it's good to remember all the applications of the basic stuff!)
Your videos are always high quality and very informative. I was looking for a relatively simple circuit for over current protection and viola, you just happened to post a video on it! Keep on posting these awesome videos! :)
Thanks for sharing so much info in your videos. I always find them interesting. I have been looking for a circuit that does not use relays and does not dissipate huge amounts of power and can limit the current to some adjustable value but does not shut down the circuit. This is probably some kind of CC circuit. ACS 712 is a good choice for the current sense.
LM358 tends to work well on Vicm (common-mode input voltage) close to its negative supply. Vicm on circuit in this video close to its positive supply, so other type op-amps such as LF353 or LF412 or TL072 or TL082 more fit to this purpose. excellent explanation, excellent video. cheers from Indonesia
I'm surprised the circuit actually worked. The datasheet for the LM358 states the maximum input common mode voltage is 1.5V less than Vcc, which he clearly wasn't meeting here.
Besides, due to teensy mikes and speakers, it would be a little 'snap'. Not the big firecracker-esque POP with lots of room reverberation you'd hear in person. Foley artists go to a lot of trouble to make gunfire sound like 'gunfire'.
if you used a mosfet instead of the relay and let it oscillate freely then filter the output with a couple of a by-pass capacitor you could have made current limiting circuit
@@jamilhneini1002 sorry but no, P-Channel MOSFET FDWS9509L -F085 has only 8mOhm Rdson and can handle 65A and the price is $1.46 USD while this relay is 50mOhm contact resistance for 1A with a price of $1.34 EUR , not mentioning that the MOSFET can shutdown the rail lightening fast compared with a relay, and the MOSFET is way smaller than the relay, latching mechanism can be added by using a diode as feedback in the comparator so no problem there.
I can't afford to help you with your channel, However, I didn't want to thank you for the information. You have encouraged me with your many projects, even though many times I have no clue to what you are talking about, but this will come in time... As I spend more time doing electronics, being self-taught is always a long process... Learning how to code Apps, at the same time, and many other projects... Anyway, thanks again... Keep up the good Work and May GOD Bless you and yours... AMEN...
I dont know why I watch these videos since I have no fucking clue whats going on 90% of the time xD But none the less, I do love watching them :D Keep up the good work Scott!
Only 1 transistor is needed. 2nd op amp output goes trough lets say 10kohm resistor to transistor's base. For reset, push button connects to transistor's base and to ground. When the relay is on, voltage on current sense resistor goes to 0V therefore non-inverting input has higher voltage than inverting input. So the output will be near power supply level (depends on op amp's gain) and that makes 2nd op amp's non inverting input be higher than inverting input, so the output will be high as well. That way transistor stays on forever which makes relay turned on forever until you reset with push button.
THANK YOU i tried to make this in my diy power supply but it it worked on bread board, but not in a PCB i tried to find video's about a simular circuit but nobody made one thanks for fixing my problem
You need to upload more than once a week your videos are amazing. I've been watching your videos for like 2 years and have enjoyed every video I've watched, keep up the good work it would be great to see more content though!
If you look a little closer, the first stage op-amp is a complex Wheatstone Bridge, the second op-amp can be replaced by moving the adjustment to the Wheatstone bridge.
This was actually the kind of video i was waiting for. About 3 days ago iv been working on a short circuit protection circuit, though i didnt use a relay. Iv been using thermal fuses, which is kinda crude, but you get the idea. Great video though 👍
You have to build 2 of them because if you make the protection circuit you need to protect that circuit to prevent high current flows if you make a mistake in the protection circuit..
Reminds me of what i tried to create recently with discrete components: Low voltage high current stepdown converter. Didn't work as intended....first the OpAmp and the Mosfet kept ringing, after a small redesign i would have needed a mosfet driver and the last attempt was simply too bulky for the projects i wanted to use it in. maybe i should just get a finished chip for that. Now the next thing is a switchcap power-controller for a 12V PC fan. And DTFM data transmission using arduinos.
Its great, but I think relay systems are slow compared to solid state switches. And also there is the problem of the Vcc powering all the devices an voltage references. Finally, there's still a current leakage going to the load.
I think improving the circuit design can be achieved with a low power adjustable voltage regulator, and adding a half bridge rectifier at the differential OpAmp output to make it work with AC.
@4:50 "obviously closed".. erm, yeah, obviously... wut? I'm glad I can skip back and watch it again. It's very clear, just quite fast for a novice like me. ☺
hi i would have used the second contact to break the circuit between the coil and the top of q2 and the push button across the contact that would prevent the button allowing full current while it is held (5:14)
man legit said "i drew a more professional circuit schematic" after drawing the cleanest looking hand-drawn schematic
Your writing and drawing is absolutely perfect.
ffio
I just loved that shot at 0:28, showing the current rising and the cap pieces flying all over. It looks like a B-movie gore shot.
Misac Tiba ya nice XD
Same, they blow really cool
probably from 1:01
I just want to draw attention to how perfectly you explain the design methodology.
Every step highlights a solution, and resulting problems. Rinse, repeat.
This makes an otherwise daunting looking circuit, really just look like 4 or 5 small very straightforward circuits stuck together.
Legend.
Thanks for the feedback ;-)
What the hell, literally less than 20 hours ago I was scouring the internet for a good guide to short circuit protection. GreatScott couldn't be more perfect.
what if the diy go wrong and create a shot circuit
Electroboom needs this, considering the amount of wrongly polarized capacitors.
GIMME DA METAAAA
GIMME DA SCOPE!!!
LOL, True that :D
xD
you damn right
Oh come on, I guess you don't want to undermine the meaning of his life by some overcurrent protection circuit :)
This is EXACTLY what I was looking for and you even addressed the infinite loop question I had. I haven't done electronics in 10+ years and my brother wanted me to make him something. Turns out I've forgotten everything and it was very daunting till I came across your channel. Thank you very much!
Its pleasure to watch the way you briefly describe projects .................
Wow, dude... I understood that whole schematic as you described it -- that's like the most complicated schematic I think I've ever been able to understand! -- You did really well breaking out each component and explaining it separately. -- Thanks, man! :-)
This is my fav video because its a complicated looking circuit but built and explained part by part
Yes, I most certainly enjoyed the video. A year from now I'll be able to design my own circuits thanks to your instruction. I'll just toss in a comparator over here to turn that off; ... right off the top of my head.
Thanks, I watch your videos almost daily.
I think every electronics hobbyists can benefit from something like this that's simple and reliable for circuit protection.
Love your stuff! Plus, no one could ever complain they can't read your writing either! Thank you.
Your writing is so perfect! I don't know how you do it!
How come I have never come across such a great channel all my years of youtubing till year 2020
You are awesome sir
I literally never build anything GreatScott makes, since I never have the right parts, but I love knowing the information is there when I need it :)
You just like drawing circuits don't you?
Good thing you're good at it. 👍
Your schematic drawing and hand writing are awesome
What i read:
DIY Short Circuit
Ok.
That escalated quickly.
Oh, you're one of them? Well we mustn't judge.....
Skyfighter64 o
selective reading
Mehdi joined the chat.
you make the best simple, clean and well explained tutorials
As usual Scott is Great in his video. I love the detailed explanation.
The problem that I foresee is that with a 12V supply, the inputs of the first LM358 are sitting at around 11.4V. Unfortunately, the LM358 has a specified common mode range of only up to Vcc - 1.5V which would be 10.5V with that supply. Now, you may be lucky and find that the opamp works with its inputs at 11.4V, but it's not guaranteed. The inputs are PNP Darlington transistors with a current source in the emitters and just can't operate very close to the positive rail.
Worse is if you use a lower voltage supply like 5V, when the opamp's inputs would be at 4.76V with a maximum common mode range of only up to 3.5V. The behaviour would be quite uncertain in that sort of case.
The simplest solution is to monitor the current low-side. That is, you put the current sense resistor in the negative line, which is a common approach. Then the inputs are close to ground, but that doesn't matter because the LM358 (and many similar opamps) include the negative rail in their common mode range, so are guaranteed to perform as expected.
I love the videos Scott! I had to mention though that you can get short circuit protection and more all in one IC. Texas Instruments tps2h160 is a 2 channel high side switch with short, reverse, current limiting and temperature protections. Simply set the current limit with a single resistor and send logic level from your favorite mcu to the inputs. As of March 2020, it's a whopping $1.63 US.
Thanks buddy for a simple protection circuit👌👌
You're welcome :-)
the last bit about using a fix resistor i believe if the supply voltage changes it will still effect a resistor unlike some zener or regulator please correct me if i am wrong
Šƫőȓɱ КІЛջ
He said "fixed voltage." ;-)
oh...... thanks
Thomas Cruz
LM4040. Somebody is playing with the good stuff.... The challenge for this circuit is the need for an extra reference voltage. For the scavengers and poor boys like myself, a simple TL431 will work. They can be found on almost every AC to DC switching type power supply made for consumer goods :-)
Nice work. You could have connected the opamp power to the relay output to get a cut off latch. The second relay can be eliminated. For the reference voltage, you can use a 4007.
Really great video. I like your Quality and the Ideas. I think I will recreate it.
ToDoList That s right
ToDoList I agree
Awesome :-)
On YT it is called "Inspiration" and isn't it fun when a dozen channels are INSPIRED to do the same video in the same day?
John Possum I don't want to upload this. I thing that I Create it only for my own
I really enjoy your videos. The way u demonstrates it with pen and paper. Loved it! keep posting such lovelies..
Nice circuit, perfect DIY solution and easy op-amp introduction.
Is this only me that watching this as a 11 years old kid and confused? But subscribed to this channel and always watch the video?
Am i the only one who doesnot undrstand anything but watches it
Edit : i also wanted to say his videos are interesting even tho i dont understand
No, I feel lost pretty early on the video but still watch the whole thing.
i too didnt understand when i was in college later i realised the same requirement then same video understood
nope
Me 2 !!!
Keep watching then mate, the more you watch and take note the more you will come to know
Simply and effective design, i am thinking about building my own copy. Thanks for sharing.
For even more simplicity, you can use a single channel power switch IC to provide a fixed voltage overcurrent and reverse current protection. For 500mA or 1A, I recommend the STMPS21X1.
i got my variable lab power supply for 40 bucks from china. they arent that expensive. everyone should invest that money. they are so useful
Congratulation!...your explanation is easy to understand.
I liked the video right away, this is a very nice project although, in my opinion, it ended up being a little too big for its purpose. But it is a very nice introduction on this topic and could be used to compare with a purpose built IC, like the LTC436x series.
Looks like a great IC. I will have a look at it.
yeah there's purpose built IC almost for everything now!
But well this is a cool _weekend project_ that some might be able to built with parts that already they have.... and a good middle level electronics to learn from! (which makes a good TH-cam content... I'm an electronic engineer and it's good to remember all the applications of the basic stuff!)
GreatScott! Hola soy.aficionado a la electronica...si pusieras estos videos tambien en ESPAÑOL serias el mejor canal de youtube
Great video. Thank you for showing and explaining how to do this. This is one I will actually build.
Your videos are always high quality and very informative. I was looking for a relatively simple circuit for over current protection and viola, you just happened to post a video on it! Keep on posting these awesome videos! :)
he has the finest hand draw circuit
Why hasn't this channel hit one million subs yet?
60 years ago you would have been a STAR at Tektronix heading up the "schematic documentation branch"... and even more legendary now :)
Something about that capacitor fluff hitting that meter in the intro makes me appreciate the quality of your camera work.
you deserve 1 billion subscribers
Thanks for sharing so much info in your videos. I always find them interesting.
I have been looking for a circuit that does not use relays and does not dissipate huge amounts of power and can limit the current to some adjustable value but does not shut down the circuit. This is probably some kind of CC circuit. ACS 712 is a good choice for the current sense.
LM358 tends to work well on Vicm (common-mode input voltage) close to its negative supply. Vicm on circuit in this video close to its positive supply, so other type op-amps such as LF353 or LF412 or TL072 or TL082 more fit to this purpose.
excellent explanation, excellent video.
cheers from Indonesia
I'm surprised the circuit actually worked. The datasheet for the LM358 states the maximum input common mode voltage is 1.5V less than Vcc, which he clearly wasn't meeting here.
I can finally follow these videos now
Supersložité. Pořídím si regulovaný zdroj a napětí zvyšuji pomalu. V případě zkratu protestuje Ametr.
This video seemed to make a lot more sense than other videos
Why didn't you let us hear the capacitor exploding ?
I often listen to music while recording. So the explosion was not useable.
Thanks for replying and great video as usual.
GreatScott! Q&A what music do you like ? xD
CoHxBlackWebster
Beatles!
Besides, due to teensy mikes and speakers, it would be a little 'snap'. Not the big firecracker-esque POP with lots of room reverberation you'd hear in person. Foley artists go to a lot of trouble to make gunfire sound like 'gunfire'.
Thanks Scott now no one will be afraid when i turn on my circuits
That was my intention ;-)
GreatScott! Love you Scott👍😊 your videos made me choose electronics in college
Awesome :-)
You destroyed a breadboard for us. Much respect!!
if you used a mosfet instead of the relay and let it oscillate freely then filter the output with a couple of a by-pass capacitor you could have made current limiting circuit
Yeah but relay has lower power loss
Jamil Hneini but relay can't oscillate fast enough for the current limiter
Camilo Mason I don't think you need it to oscillate right? Just close it when there's no overcurrent and open it when there's no overcurrent
@@jamilhneini1002 sorry but no, P-Channel MOSFET FDWS9509L
-F085 has only 8mOhm Rdson and can handle 65A and the price is $1.46 USD while this relay is 50mOhm contact resistance for 1A with a price of $1.34 EUR , not mentioning that the MOSFET can shutdown the rail lightening fast compared with a relay, and the MOSFET is way smaller than the relay, latching mechanism can be added by using a diode as feedback in the comparator so no problem there.
I can't afford to help you with your channel, However, I didn't want to thank you for the information. You have encouraged me with your many projects, even though many times I have no clue to what you are talking about, but this will come in time... As I spend more time doing electronics, being self-taught is always a long process... Learning how to code Apps, at the same time, and many other projects... Anyway, thanks again... Keep up the good Work and May GOD Bless you and yours... AMEN...
I've got few neanderthal genes. I see caps blowing up. I click like.
I do This! It Works! Befor this my Lab bench power suply Are blown Up!
This is great in combination with my DIY power supply. I think I'd also add a buzzer so when there's short circuit it would notify me with a sound
I dont know why I watch these videos since I have no fucking clue whats going on 90% of the time xD But none the less, I do love watching them :D Keep up the good work Scott!
Only 1 transistor is needed. 2nd op amp output goes trough lets say 10kohm resistor to transistor's base. For reset, push button connects to transistor's base and to ground. When the relay is on, voltage on current sense resistor goes to 0V therefore non-inverting input has higher voltage than inverting input. So the output will be near power supply level (depends on op amp's gain) and that makes 2nd op amp's non inverting input be higher than inverting input, so the output will be high as well. That way transistor stays on forever which makes relay turned on forever until you reset with push button.
what about making a video for variable current limiting circuit like lab bench power supply
Food Gamer فوود جيمر
Already done. Check HACKED!
Emmsey Square2
Seen😁
All starts with a bang. Nice touch.
Magic smoke my speciality, have made so many versions of the magic smoke machine, maybe with this I can make something else.
Best GREATSCOTT vid ever. Thank you bro.
THANK YOU i tried to make this in my diy power supply but it it worked on bread board, but not in a PCB
i tried to find video's about a simular circuit but nobody made one
thanks for fixing my problem
You need to upload more than once a week your videos are amazing. I've been watching your videos for like 2 years and have enjoyed every video I've watched, keep up the good work it would be great to see more content though!
Sure, I would love to upload daily but quality takes a lot of time. This video alone took around 30-35 hours to produce.
you are pure genius bro i like tour videos so much
Wow really nice circuit! Thanks Scott!
If you look a little closer, the first stage op-amp is a complex Wheatstone Bridge, the second op-amp can be replaced by moving the adjustment to the Wheatstone bridge.
Great a protection CIRCUIT for failing at soldering circuits👌
1:01 : "lets get started" (pop..) 🤣
All I hear is stuff I don't understand but I still watched the whole video because it's great Scott 😉 dun dun tsss
This schematic was incredibly well exlained! I admire your designs and detailed commentary.
Freundliche grüße aus mexiko!!
great sccott is
awesomEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
guys can i get 4 likes
fuck off
nut:HAHAHAHAHAHAHA whats a new joke
aaaawwwwwwwwesome***
aakash tahir fuck on
Your vídeos make love the electronica
You are right. Electric boom need this
This was actually the kind of video i was waiting for. About 3 days ago iv been working on a short circuit protection circuit, though i didnt use a relay. Iv been using thermal fuses, which is kinda crude, but you get the idea. Great video though 👍
My brain explode trying to follow this video
i liked that capacitors explosion
Just what i needed for my motor overload protection!! Thanks a ton !!
OMG Scott, your drawing skills are amazing!
You have to build 2 of them because if you make the protection circuit you need to protect that circuit to prevent high current flows if you make a mistake in the protection circuit..
Burnt up ICs and exploding capacitors, Great Scott!
you could probably use a normally open Momentary push switch between the transistor base and ground instead of the blue Colored bistable switch
Reminds me of what i tried to create recently with discrete components:
Low voltage high current stepdown converter.
Didn't work as intended....first the OpAmp and the Mosfet kept ringing, after a small redesign i would have needed a mosfet driver and the last attempt was simply too bulky for the projects i wanted to use it in.
maybe i should just get a finished chip for that.
Now the next thing is a switchcap power-controller for a 12V PC fan.
And DTFM data transmission using arduinos.
Congratulation 600k subs
Thanks
Thank you.
I can see this being a useful addition to a diy bench power supply like an ATX psu along with a display to show the cut off values.
:)
Those hand drawn schematics are practically pornographic. Lol
Its great, but I think relay systems are slow compared to solid state switches. And also there is the problem of the Vcc powering all the devices an voltage references. Finally, there's still a current leakage going to the load.
Great project man !!!
Brazil here!!
You can turn the bistable switch into a push button by opening it and removing the little spring inside :D
Well done! Obviously, for large inrush current, a resistor is not the way to go, rather a thermistor.
Nice presentation
Forrest Mims for this generation. I am still learning!
Awesome! You always do excellent projects and very well explained. Thank you.
As always ty for your time and knowledge my friend.
I think improving the circuit design can be achieved with a low power adjustable voltage regulator, and adding a half bridge rectifier at the differential OpAmp output to make it work with AC.
Half bridge would explode in current got to big
bro wow love watching your projects
@4:50 "obviously closed".. erm, yeah, obviously... wut? I'm glad I can skip back and watch it again. It's very clear, just quite fast for a novice like me. ☺
Incredibly awesome project👍 thank u for the idea
hi i would have used the second contact to break the circuit between the coil and the top of q2 and the push button across the contact that would prevent the button allowing full current while it is held (5:14)
Very cool video, I appreciate the time that must go into getting each shot of you editing your drawn schematic; great B-roll!
Very usefull for my projects and thanz to informed us to the developing paths in practicle. Thanz lot!!