LM317 Adjustable Voltage Regulator Tutorial

[TheTubejunky]

Thank You again Afrotechmods! This circuit is perfect for a laser diode driver!

Its a true gain to hear you mention the use of those caps.

[sapher974]

Working as I excepted, Thx from a beginner

[MrJumpersun]

@Sanyuuu If he 220V are AC you shall use a normal transformator => see his transformator video

[MrJumpersun]

@rgda91 you can only convert DC Power

[rgda91]

@MrJumpersun figured it out after 2 burned variable resistors :(

[rgda91]

what's the input power?

can i convert 127V AC to a 24V AC and then a diode pack and after that your circuit?

will it work?

[YordleCity]

2:07 is that a variable resistor or a potentiometer?

[YordleCity]

@YordleCity Never mind the variable resistor is a potentionmeter. . . All good! I'm getting there :)



[KIBProductionz]

what's a better voltage regulator? a zener diode or an LM317? i found out that zener diodes go up from 0.01V up to 12V if certain configurations plus a darlington transistor is considered

[Afrotechmods]

@KIBProductionz Any voltage regulator IC will be better than a zener. The zener voltage can easily vary by +/-10% over their full current and temperature range. Sometimes that's good enough though.

[Sanyuuu]

What is the best way to reduce 220 volts to 12 volts ?

This one doesn't seems fine because of heat.

[n0n570p]

@Sanyuuu see his videos about transformers

[mspeir]

How do you calculate R1 if R2 is 50K?

[psp10004]

i know that google is your friend, but is there a chip that i could control over serial or pwm (with an arduino) that could output precise voltage and maybe limit current?

[ideeman1994]

Thanks for the tutorial, very clear and easy to understand! :)

[TheLionRichard]

How do you use a potmeter to control the voltage and current through the mosfet? Won't all the power go through the pot as well, making the mosfet almost redundant?

[psp10004]

But i don't have a heatsink.... *cries

[achemachew]

@psp10004 Take apart a computer or any power supply and you should find plenty heatsinks there!

[TechKidusa]

is there a higher power version of these because im going to use 72v at 50a?

[meluchis21]

I have to do this circuit but I see that I'm using 100uF instead of 50uF you are using and my first capacitor is 4.7uF. Is fine if I use these values?

[AlexxSR]

Give me your knowledge!

[funkmastertraf]

Hahaha Barracuda at 0:39

[fm607216]

What is the maximum current that can be drawn thru this circuit? My input voltage would be 0 to 18vdc. I would like the output to be 0 to 12vdc (12 dc max) The motor has a maximum of 12 vdc and draws up to 1 amp. All of my train engines work on o-18v This engine has a motor 12vdc motor . I'd like to install this circuit in the engine so that someone does not overheat or smoke this motor by accidently turning up the track voltage to high.

[NigDub]

I am looking for a way to make a step sequencer for my synth. When I looked at your circuit I was think if I could make timer circuit that would switch between pots at a tempo that I could regulate with another pot then I will have the solution because a voltage can be converted to midi data (with a doepfer system) but do you maybe have an idea for a second circuit to switch between pots?

[blindassassin111]

Where did you get the 5875 in that equation?

[pseudorandomly]

@blindassassin111

Start with the original formula: Vout = 1.25 * (1 + (R2/R1)) + 0.000050 * R2

Now R2 = 4.7k, so Vout = 1.25 * (1 + (4700/R1)) + 0.235

Multiply the 1.25 through the parenthesized expression: Vout = 1.25 + (1.25 * 4700)/R1 + 0.235

[remembering that x * (a + b) = x * a + x * b and that x * (a / b) = (x * a) / b]

Then Vout = 1.25 + 5875/R1 + 0.235

Finally, adding the constant terms: Vout = 1.485 + 5875/R1

[rob8675309ain]

You kind of remind me of KIPKAY

[CognitiveNetwork]

HELP. So you don't need any precision scale (Potensiometer controll), in order to turn the pot? The one I have has just a plain metalic rod. So my fingers won't slide, making it impossible to turn?

[CognitiveNetwork]

Or see how much it takes to blow something up. LOL... reminds me of my mobile detonator project I'm working on...

[CognitiveNetwork]

I'm working with LM units. But, what does LM stand for?

[L1ne3]

did the "50(micro)" on the equation at 2:32 came from the Vout capacitor? what if my capacitor is rated at 50 volts and 3.3 (microfarad)? what do i do?

[Afrotechmods]

@L1ne3 No - as I recall it's from a 50uA bias current. So just do (50x10^-6)xR2.

3.3uF is fine.

[L1ne3]

@Afrotechmods Thanks. I still seem to have problems.

I have a 100k potentiometer and i want the max out to be 5 volts. I cant seem to figure out how much R1 should be.

[Desmaad]

@Afrotechmods What exactly is bias current, anyway?

[KevinByrne2]

@Desmaad -- The "Adjust" pin on the 317 voltage regulator draws a small amount of d.c. current during normal operation (about 50 microamps). That current is the "bias current". The bias current would have to be considered only in low current or low power applications, but you wouldn't use a 317 for such applications.

[MattiasOfTheMetal]

Thanks for the informative tut. Had to show my roommates the part when you blow up the resistor. haha

[justin18349]

but why my pot is heating up when puting a load on it???????for example I need it to power up a 12v led and the pot just started to smoke.

[viquem02]

Afrotechmods: The best educational videos, very professional, these videos make you wish to learn more and more, this man knows how to teach electronics, is awsome.

[013dirtdiver]

is there a way to make the min voltage 0

[Afrotechmods]

@013dirtdiver Not with this circuit.

[SVIJ1991]

HI Afrotechmods

i need to regulate dc voltage between 0-5 is it possible with this kind of regulators

[ImUrtastyflava]

Im thinking of getting one... But use it as somewhat like a Dc converter.

I have 6 volts/DC going in and I want to boost the output to 12 volts and more :)

Is that possible?

[gschaaf713]

@ImUrtastyflava build a voltage doubler circuit or use a transformer. A regulator wont put on more than the applied voltage.

[ImUrtastyflava]

@gschaaf713

Thank's, but I found a dc to dc boost converter on eBay for about 9 bucks. Works perfectly!

[And333777]

А почему на русском не переведено((((((((((((((((((

[KyleCarrington]

Could you do a video on switch mode power supply building?

[justin18349]

is it all right if I use a 470 ohm resistor????????or higher than 510 let's say about 600 or 610 is it good or not?cus I've put a 50k potentiometer and it has released the magic smoke and I need to buy another one

[bluetorch13]

ok... I did basic research (or less than basic) and couldn't find the difference between a Voltage Regulator and a Potenciometer. Yeah sounds very ingnorant. lol! why can I use a potenciometer to control the fan directly? or a light?

[Afrotechmods]

@bluetorch13 Watch my voltage divider tutorial video. In short, it's extremely inefficient to use a potentiometer to supply any more than a few mA. Also the voltage output won't be as reliable (hence "regulated")

[bluetorch13]

@Afrotechmods Thanks!! I'm planing on starting to build LED drivers. Your vids are more than excellent.

[5445252]

hahah i think this guy is from the A Team or something. but look at the Jamco sided and you will see his face pop up hear 0:39

[BAXFAXTER]

КПД 1%

[meade9166]

is there a bigger version then the LM 317?that can take more amps?please answer

[Afrotechmods]

@meade9166 LM150



[meade9166]

@Afrotechmods thanks

[AcousticBruce]

Why did you pick a value for R1 the first time (with potentiometer) and then pick a value for R2 the second time (non adjustable)? Could you have accomplished the same thing picking a value for R1 again (without potentiometer) and figuring out R2 with equation?

[scanjet1600]

Did someone else noticed Mr. T at the 00:43?

[R2Processor]

Wow this is very helpful! Just a question, I am making a laser but do the resistors connect to the ground of the voltage regulator? and on the laser diagram it shows the resistors in "parallel" and would 1 ohm and 4.25v output 1.25v and does the ohms change the voltage? if so what would 2 ohm do and 3 ohm and so on? and if not does it change the current? if so do what I said above :P Sorry for not googling this but I really have no idea what to put into the search bar...

[Tranqspogi]

your variable resistor is 50k or 70k?

[digitalPimple]

What options do you have if the load being regulated could potentially draw up to 20 amps?

[Afrotechmods]

@digitalPimple You need a synchronous switch mode power supply

[AdeptAlbatross]

So what was the equation for that resistor bursting into flame? Psycho electronics techie + voltage = burning everywhere/everything.

[Buitreman100]

no spider sense!!! xDD

[erkitboy]

From what I understand the maximum current output from this regulator is 1.5A. Correct? Any suggestions on what I should do if I need 10A of current from the output?

[TheMegalucian]

why don't u just use a potentiometer ??

[diego70827]

in spanish please

[Wkterr]

1 Resistors was harmed in the making of this video.

[Kamenos4ever]

dude I love your videos. thanks a lot this helped much!

[Jhfgsjdcd]

What kind of potentiometer is used

[projectdimpreza]

can i use this as a tattoo machine power supply.. i know potentiometer cant handle high voltage devices.

[reactor1system]

I have a question though. How can you regulate a voltage that varies greatly? Can I use the LM317 for that? For example, energy produced by a dinamo that is first transformed to DC current, will vary quite a lot. Let's say the dinamo will usually produce around 6V but in reality it will be less or more, and I want a 4.5-5 volt output.

Without any load, I've measured such a dinamo outputing even 18V! (a bycicle dinamo).

[Afrotechmods]

@reactor1system Use a diode+very large capacitor to have a more stable voltage on the input before the LM317. Or buy/build a SEPIC DC-DC converter.

[oM4rE7]

Ow, this is great and easy to do.. Sir, I have a question. I am just a beginner in electronic, If I use 16 volts input, it means I can get 1.25 - 13or14v? Am I right?

[Afrotechmods]

@oM4rE7 yes

[KissoftheQtip]

I love how all of your clips are singed haha. Great videos by the way, very useful for an EE student like me.

[motorhead45102]

also if you can send me a parts list of what you used

[motorhead45102]

Now im working on making a 4 fan variable speed controller, would this variable vregulator be able to hand 4 computer fans as long as i have a good heat sink and would it be a good idea to have those capacitors in the circuit for just controlling some fans or could i go with out.

[Demoman42]

Made it :] Using 35V power supply , mostly using low current under 12V. added HUGE heat sink and fan to it. So no more heat up ;D

[RavenRof]

Nop.... Tried with a 12v 500mA power supply and still get the 1.25v volts on the vOut... I dont get it.

[Nadrealis]

@RavenRof Make sure all your math is correct.

[RavenRof]

@Nadrealis Fixed the problem ;) my LED's were consuming 2.3Amps of current and the LM317 is only rated to 1.5Amps. Switch to the LM338 and its working fine =)

[Nadrealis]

@RavenRof Those must be some powerful LED's or you must have a shitload of them haha

[RavenRof]

I believe that hte problem might be that, i want to output 3.7v with a vIn of 5v. that breaks the rule of keeping the difference between vIn and vOut around 2 or 3 Volts. I need a better power supply. Am i correct? or at least near? =)

[RavenRof]

for some reason my LM317 is stuck at 1.25v at vOut.

R1= 240ohm

R2= 470ohm

that should give me 3.7V vOut.

Im using a 5V 2Amp power supply. The 5volts are going inside the LM317 but whatever resistors i use on R2 it seems to be stuck on 1.25v x_x

[Bylga]

I have no idea what you're doing but it's great stuff.

[clintdavistv]

Alright Afro!! Im following your stuff! Hit me!

[haz939]

Hey, I building this but the voltage wont adjust with a 10k pot, the output voltage its exactly the same as the input voltage the pot makes no difference. I'm using an 510 ohm resistor like you.

[shadowmage1988]

Excellent video, had an LM317 lying around and was trying to figure out how to use it and was wondering why the voltage was never varying even when I checked the datasheets. Never added a R1, since I thought I didn't needed it(and never paid attention to the equation in the datasheet).

[sergiomarchena]

thank to help us , very good video my friend , I learn a lot with it

[ivaneduardo747]

@dealio82 Yes, but I think it's an overkill.

[dealio82]

Can i use a 10 turn pot?

[jayagk]

as always your vids rocks!!

[obaidish]

nice video every thing was told very preciesly.thanks.

[DraaxDard]

Thanks for a great video! Been checking your channel every day :)

[pcbheaven]

excellent video! congratulations. i will feature it in my site today

[Afrotechmods]

@pcbheaven Thank you!

[Secants]

I see a certain 'T' at 0:40 ...

[steeljan]

Very nice.  Thank you.

[bananastalktome]

Shouldn't the schematic indicate the 0.1uF cap as a non-polarized one? I was confused when you said to use a ceramic cap but the schematic in the video indicated differently. Nonetheless, great video, as always :)

[Afrotechmods]

@bananastalktome oops... copy and paste error! You are right.

[clodester]

I love your videos, they are so clear and easy to understand. Plus you have a brilliant voice. Thank you so much for taking the time to make them.

[superTransformer99]

can I take two lm317 Voltage Regulators and connect them in parallel do I get dual amps? sorry for my bad English.

[Afrotechmods]

@superTransformer99 It's worth trying. If you put 0.1 ohm resistors on the output of each regulator then tie the other side of the resistors together it will definitely work.

[dumle29]

@Afrotechmods @Afrotechmods did it without the resistors and it didnt work. i also read online that you would need some extra components. I didnt know what those components were so i bought a LM338 instead. havent gotten to test it yet, but it should work.

i used the lm338 instead because it can take 5 amps of current i got the one in a TO-3 STEEL

Metal Can Package and attached it to a bend aluminum plate with plenty of thermal grease :)

so a 3 amp (the transforer is 3 amps) 12v supply :D

[pcbheaven]

that is one cool theory video. the owon and the fluke are sweet! i will feature it these days in my site for sure. keep it going.

[o2me2]

Thank you so much. Your videos are greatly appreciated.

[reactor1system]

Thanks for making this videos. I appreciate your effort ;).

[ggattsr]

Thanks for taking all the time and extra effort to produce such high quality, easy to understand video tutorials. Hopefully more are coming.

[MrHorsetail]

Thanks for the good electronics instructions, they are very helpful. Wouldn't the 1/4 watt resistor you had hooked up there fry, if you used the power supply to supply a 7.8 watt load?

[ladedk]

Really good video, as usual!

[tomattosfutleimierda]

notice the durasmell battery

[Intosia]

How can you determine the output voltage without a load? (adjustable). You can never read the voltage, set it to 5V and then hook it to a circuit. Because the voltage isnt right w/o load...?

[Afrotechmods]

@Intosia Hah! I'm an idiot for forgetting to talk about this. Basically you should hook up your multimeter to the output, measure the voltage, and make adjustments accordingly. Once you've got the voltage you want, connect up your load.

[Intosia]

@Afrotechmods Well, that what doesnt work for me... Withload load (just the meter), i get a wierd range like 8-12v. When i connect a 10K resitor load it works fine. Is that the way to use it? Im using a small (smd) LM317 based pcb from Ebay.

[Afrotechmods]

@Intosia Ahhh... well depending on the feedback resistors used in the design you may need to put a small load on the device for the output voltage to be stable. So yeah measure it with a 1k load or so.

[Intosia]

@Afrotechmods Cheers man :)

[Intosia]

The MR T pic _O_!

[ExtremHybrid]

MORE! MORE! MORE! We need MORE Afrotechmods!!! PLEASE!!

[catatonicprime]

You said "National Semiconductor and Texas Instruments," I choose to believe you said "and" instead of "or" because of the up coming merger. Great video, highly educational, will refer to it when I need a voltage regulator.

[Afrotechmods]

@catatonicprime lol... the script for this video has been like 6 months in the making... totally forgot to update that part.

[catatonicprime]

@Afrotechmods Yeah I figured you probably didn't intend it that way, but look how conveniently it's worked out! :D Also I love all of your videos, please keep up the amazing work.

[Pelle4495]

Thanks a LOT! Was googeling with no success and you just told me in 4 minutes!

You really are the best electronics instructor on Youtube. Keep them coming!

Durasmell! LOL

[GTXAbunada]

Just noticed 0:11 "Durasmell", lol

[CoolDudeClem]

I've used the LM317 and 337 (for split rail power) in a power supply I made, easy parts to work with and quite reliable.

[fabiuh991]

HAH! finally found why you are called "Afroman" lmao now it makes sense xD

I know it can be really boring everyone making you questions, but have you any tutorial on how to make a circuit to switch automatically between a mains>12v tranformer to a LI-Ion 12v battery, like an emergency backup system, when main power gets cut off it switches to the batterypower.. Aaand when the mais are on, the circuits charges the batteries..

All this is for my door lock..

Thanks in advance =)

[36trooper]

Awesome video as usual!

Thanks for posting this.

[Shaunakde]

Hi,

It it very difficult to make a hobby grade switched power supply? Are there any ICs that I can readily use? I have no particular application in mind. I just want to make one coz I am intrigued by them and think they are cool!

[Afrotechmods]

@Shaunakde Here's the problem... building DC-DC converters on a breadboard gives dreadfully noisy outputs. Building them on protoboards is slightly better but still crap for high currents. The right way to do it is carefully etch your own PCB or buy a pro made PCB. But once you are paying for all the components plus all the effort to make the PCB you might as well just pay $10 for an off the shelf solution. Anyways... National Semiconductor's "Simple switcher" line are the easiest to use.

[Shaunakde]

@Afrotechmods Thanks for the reply. You make a fair point about off the shelf solutions being good VFM. One more question - Are the ones that are typically used with high power LEDs also of switched type?

[Afrotechmods]

@Shaunakde Yes, but LED supplies are switchmode constant current supplies whereas normal DC-DC converters output a constant voltage.

[ciprianwiner]

thanks a lot man for the tips:D

[tjnlsn255]

Excellent videos!

Can you make a video using a 2n3055 transistor(s) to increase the amp capabilities of the voltage regulator and how that must be related to the input source.....

Thank you again for excellent and easy to understand videos!

Todd

[joshstube]

Great video as usual, good teaching. I've use this chip before but never paid attention to the inefficiency calculations.

Can you going to make a video on the more efficient yet more complected switching regulator?

Thanks Again for all of your videos!

[kekejojo1212]

Neat. I'm actually very glad you made this video now. I just subscribed to your channel a few days ago and I was pleasantly surprised to see this because I am about to build a solar 4 AA Battery charger using this component. Good timing and thanks!

One thing I dont really understand is .. why do you need two resistors? Is the "Adjust" pin like an input type or output type? (Which way is the electricity going there?) Why do I need a resistor from output to adjust? Cant I just have one on ADJ?

[HarryMatic]

Don't get me wrong Afroman, these videos are really good, clear to understand and very well presented, but there hasn't been a project like the snapple cooler for a while.

[prince22gs]

u r a good communicating teacher

[fahmicanaries89]

may i used irfz44n for control high current dc motor?

[fahmicanaries89]

fuhhh! that good... may u make a tutorial how to control dc motor using pwm.. really wanna used it..

motor speed: 4000rpm

max amp: 36 A

voltage: 24v

[darwyn13]

hey spider sense! please make a tutorial on how to make an INVERTER!!! Please!!! thanks!!!

[RatkoUSA]

Outstanding!

[MrLiquimatter]

you sr, are my inspiration. i think i told you before. i had done nothing with electronics, till one day i started soldering. i searched the web for information and you came up 100% of the time. and i tell you what. i would recommend you over any electronics class. thank you for teaching me a new skill. :)

[MudDeveloper]

Great, thanks! DC to DC converters would be good, too. :)

Also can you explain how, with your function generator, your oscilloscope, and a couple of extra parts, you could determine the inductance of an unknown (maybe hand-wound) inductor, or the capacitance of a capacitor?

I tried to get a DC to DC converter going, but I think the coil let me down, hence the question.

[Thercflyer96]

hey i just took apart these speakers i found in my old amp, i want these speakers to play music from my ipod, what gear would i need if i just have the leads + and - connections from the speakers. Thanks

[Afrotechmods]

@Thercflyer96 Not exactly relevant to the video but you can start by googling for LM386 based amplifiers, or research "gainclone" amps which are based on the LM1875.

[DackIsBack]

@Afrotechmods Why did you remove my comment? A modified CMOY would be waaaaaaaay more practical than a "gainclone" if it was a low wattage, portable application(I assume it is considering he is using built in speakers.).

[Afrotechmods]

@DackIsBack Because you are wrong. CMOYs are built out of low current op amps that are completely unsuitable for driving the 4 or 8 ohm speakers he wants to drive.

[DackIsBack]

@Afrotechmods I assumed he had the OOTB portable 3.5mm trs type speakers, Which are made to be powered with a wimpy line out(cmoy)...

I had a decent pair of sonys portables that ran just fine on any such amp, or without one, straight from an iPod...

[thishasgottobecrazy]

Good to see that you are back and making videos. I really enjoy them! Would you consider making a video on DC to DC converters???

[GTXAbunada]

We want a tutorial on DC To DC Converters Please.

[trance183]

@GTXAbunada That would be sweet! I also hope to see a MOSFET tutorial. :)

[5445252]

@trance183 I think he has one all reedy, but I mite be wrong