Back to Basics: LM317 Regulator

[@whitehoose]

Its maybe worth mentioning that all these gizmos come with a datasheet - and potentially confusingly for newbs often come in a range of different "flavours" and versions. A regulator I've used a lot is the LM1117, it comes either as a fixed voltage (3.3 or 5v etc) package that requires bypass capacitors to smooth the circuit output or as an adjustable version that uses resistance to determine levels. You have to be careful to get the correct type and version as well as having the appropriate extra components to successfully get things running correctly.

[@kencohagen4967]

This is a very versatile voltage regulator. I used on when I went to DeVry to supply 5 volts to a logic circuit breadboard we used with logic circuits. I didn't have an adjustable power supply at home so I set up a power supply using a 9 Volt battery. I used that because I had a 9 Volt battery holder that I got glued to the board. That way I could build the circuits I needed for the following day's lab. It worked well enough that I could go into the lab, hook up the variable power supply and Scope and call my instructor over to get it checked off. Then I had time to do homework from another class. That helped a lot as I was working full time and a newborn at home. Thanks for the video, it was a great refresher for that LM 317 as it's been over twenty years since I graduated.

[@learnelectronics]

Thanks, glad you liked the video!

[@learnelectronics]

I heard DeVry is that true? I work with quite a few DeVry alumni over the years. They taught electronics to an entire generation.

[@victorst5997]

I´ve seen so many channels on DIY electronics. Many are very good, some not so. But your style and approach suits me best. I´ve learnt so much the easy way. Thank you for your high quality work.

[@learnelectronics]

Thank you

[@SimpleEnough2k9]

We'll need an additional part in which the power dissipation will be addressed thus helping people to determine when a heath sink is required. Knowing that the necessary info is in the datasheet, this will be a good exercise guiding people how to read the information. An example with the constant current design would be nice, showing how can someone ensure a led will always be fed with the same current even if the input voltage of the regulator varies. Newly arrived hobbyists need practical examples to refer to, I think.

[@1pcfred]

I have another 10 LM317s on order and being shipped to me right now. Stock was getting low. Good luck to all on winning the meter.

[@nwaigweduke6858]

Your method of explanation is quite clear, easy to understand. But still would like you to explain how to test LM317 with multimeter without applying voltage.

[@robertneill3057]

Normally the resistor between the output and adjustment terminals on the 317 is around 240 ohms. Use the 1% tolerance E24 range of resistors to get this resistance value. Alternatives are 220 ohms or 2 lots of 470 ohms in parallel (235 ohms). With the latter value you will need to use 3 or 4 resistors in all to get more or less exact output voltage figures (2 in parallel between output and adjust. 2 in series between adjust and ground). The calculation formula given will show this requirement. With higher output currents using either the LM350 or the LM338 the resistor between the output and the adjust terminals may require to be of a higher power rating with lower output voltages.

[@NitroGuyJH]

Ahhh, the good ole 317. I’ve used a many of these and love their versatility of such a small and compact integrated circuit. Very nice video my friend

[@reeseyme9613]

i find it really fascinating how everything can possibly be miniaturize into a integrated package after building one with opamp + n-channel mosfet + low voltage regulator as reference.

[@waltchaa]

Thank you for taking the time to create these videos

[@lorandnagy6057]

Very useful and entertaining. And I like that you have regular episodes.

[@isoguy.]

Really awsome vid, please do a follow up using the pot; sure there are those thst know all this but us newbies still have to learn these things; Ive learned so much from 12v vids, totally inspired now to follow a career in electronics. So many questions: At what point is a heat sink required? Rating of resisters, how calculated? Thank you.

[@iot_enthusiast]

Good coverage of LM317 adjustable regulator basics

[@Meepster12]

Oooo a meter giveaway and a quality education? Thats 2 reasons to watch!

[@YouAllKnowBob]

Another very clear video. Very useful IC. The only other regulator I use is the 7805. Great for constant current LEDs! 😉 Stay cool!

[@1pcfred]

I use 78L05s a lot. LM723s a few times too. I use the LM337 negative compliment to the LM317 too. Here's a cute little dual PSU I made once www.instructables.com/id/Dual-POS-NEG-Power-Supply/

[@mhagnew]

So if I wanted adjustable voltage and adjustable current in the same supply I'd set up two of these?

[@georgechambers3197]

Clear and concise as usual. Thanks for another good video!

[@dalebrooks6816]

Thanks for the good video on the LM317. I have not used one in a circuit but will try it out soon. Thanks

[@levonlanderos489]

I appreciate how clear you talk, I can't stand these electronics diy videos with terrible music or a guy from India or middle east with a thick accent

[@levonlanderos489]

Please enter me in the drawing thank you

[@markferrick10]

Good video, easy to understand. How about getting into thermal considerations when the regulator dissipates a few watts of power, i.e. going from 12v to 5v and maybe .5 amps. When is a heat sink needed / suggested.

[@russelwheelwright6689]

Paul, thank you for your great videos.

[@michaelpadovani9566]

I got a bunch of those. Simple and they work great!

[@wyliewisnewski8088]

I need to drop a 1.8V lithium aa to 1.2 volts in order for my circuit to work. Do I use one of these or what is the easiest way to do this? Thanks!

[@matttodd9424]

Thanks Paul another really useful video ,along with with your other one on the L m 317

[@learnelectronics]

Thanks

[@user-be4yc2vr5c]

I hooked this exact circuit up. Cept I'm powering off a 19.5V 3.5A supply. So I'm using a 10ohm an 50ohm resistor instead of kilo. I got it to nice 6.5 volts, PERFECT 5.5V after I plug that circuit into my LM current limiter circuit(tried a whole range of resistors but either dipped below .006 or maxed at). But now I have NONE of the amps and am limited to .0060 max amps, whether I'm trying to power a big dc motor or my little LED.. I tried disconnecting the current circuit and reading just off the voltage reg. circuit since this was my suspect, an sure enough, volts are perfect, but can only manage to get .006.. Whats going on? I thought this was only supposed to reg volts and let the amps pass fairly unimpeded, so I could use my current regulator circuit to restrict the amps going to my laser diode which theoretically before thermal runa away should auto-self-regulate-the volts it needs anyway?Is my voltage regulator not even necessary? I'm confused.. LD is 5v max 1.6amp. No matter what resistance values I seem to put in there to (ranging from .1ohm - 220ohm+) just that regulated current.. I've checked like 20 times to make sure I'm hooked up right and I am. I'm starting to hear so many back and forth things and theories nothing makes sense, especially when it comes to laser diodes an "ohh you need to limit the current or they'll blow, but you can run any volts through them" or "noo you need to regulate both strictly(which I'm trying to do)" or "Volt max is the biggest danger don't go over that but can run the full 3.5 amps through the LD an it'll magically just know what it needs", an judging by the pulse function of a laser that kinda makes sense I guess kinda 50%? ....Any ideas comrades or am I just to dumb to get this?

[@eazthitman]

hello it appears in the video that the output voltage was taken from the adjust pin and I thought it was taken from the +out pin. I'm a complete noob at this so please correct me if i'm wrong. I'm trying to make a voltage regulator and constant current circuit that will output 12V and 1-20 ma variable for my colloidal silver generator. I purchased some of these LM317 and can seem to get the correct result. I got my R values from an app called electrodroid. Thanks for sharing

[@mikeoliver3254]

I just looked through my to 220 bin and I do not have an lm 317 on hand. I am going to have to take care of that, it is a very useful chip.

[@SimpleEnough2k9]

If you have a need for voltages lower than 5V, yes the LM317 can be an asset. Keep in mind that with the proper voltage divider, you could actually use a LM7805, LM7806, LM7809 and set them in such way that you can have 12V at the output, without burning anything. I bought a bag of them at the flea market for $3 so I had to find a way to use them wisely.

[@ranbymonkeys2384]

Is there a way to test these without getting the breadboard out, the calculator, dig for some resistors, get the power supply fired up, get out the mutimeter, find out a resistor was bad dig for another resistor back to the calculator and then maybe just maybe it will be good?

[@Spentelectrons]

I'm really struggling to simulate a power supply circuit to power a lm317. I have AC transformers of various voltages and have 10mf caps, ceramic resistors, and lm317 on the way. It seems no matter what I do in the simulation my input vintage is unstable. How much current is being drawn if someone were to not attach a load to the lm317? If I were to use the maximum 1.5a?

[@StRoRo]

I do love these videos.

[@KennyLong1]

More details! I love this stuff!

[@tonykamby9397]

Enjoy your videos and learning electronics, thanks

[@Th3Mafia]

There is something wrong, correct me if im wrong tho: in the circuit you have the output going out to be the power source for w.e you want. But on you bread board you are reading the output AFTER it goes through your resistor. you're measuring from the voltage divider between the resistors (that leads to the adjust) and ground. shouldnt you be reading direct from the output on its own circuit (avoiding the adjustor voltage divider) and ground?

[@lucianoiiienostacion1778]

Sir may I ask what might be the problem if my 12-0-12power supply, when switched on, goes 30V and doesnt vary

[@Venomator.]

Thanks Paul, love it when you give us interactive stuff! Bundle ordered (sorry, UK store!), calc page bookmarked and looking forward to playing! Also got some potentiometers, including the long slidey one (that was you right?), to experiment with... 👍🏻 💚 🐍

[@learnelectronics]

Yep, that was me

[@williammiller4143]

I am really interested in the constant current source you alluded to. Also, I guess on the variable voltage source you could use a potentiomenter as a voltage divider and allow for adjustable voltage. Is that the case? Thanks for an informative video.

[@learnelectronics]

Yrs you are correct.

[@savvasntouzepis8621]

Nice video ,very informative.Maybe in the next video a diy variable voltage current power supply with lm317??

[@Norfeldt]

Awesome video as always

[@robertcalkjr.8325]

Good lesson, thanks.

[@wizdumb420]

the blue wire ... sent me for a loop for a minute..

[@rrowan327]

Normally I add a cap or two to help out the lm317

[@SimpleEnough2k9]

Indeed, some situations would require the use of bypass caps, good point. Under these circumstances the datasheet will be your friend.

[@jeeplvr2000]

I have 120vdc and I want current limited to 300mA. Will the LM 317 work for this?

[@learnelectronics]

Check the data sheet for the maximum input voltage.

[@bblod4896]

I wonder if Bang Good would deliver the meter to the international space station.

[@japanesemarspathfind]

hello thank you

[@user-lc8jd6sn2b]

That formula reminds me of the gain of a non inverting op amp

[@learnelectronics]

Very similar

[@mikeburton8687]

Liked this video! Sorry about your tooth know the feeling

[@learnelectronics]

Thanks!

[@christiannielsen3863]

this thing is awesome. But why is the supply voltage irrelevant?

[@learnelectronics]

Excess voltage is converted to heat.

[@christiannielsen3863]

@@learnelectronics so supply voltage must be above output voltage obviously

[@learnelectronics]

Oh yes by about 2VDC

[@Schnurzbolz]

i would love to see it as an variable volt. regulator :) PS: LM317 Calc-Link isnt correct

[@learnelectronics]

I fixed the link.

[@BigJewDaddyAndy]

If I make the draw, you going to deliver to Oahu personally?

[@sarahtuli3611]

I have decreasing output voltage when i add the load (12v without load , 5.2v when loaded), how to solve this problem? thanks a lot.

[@learnelectronics]

What current are you pulling?

[@sarahtuli3611]

@@learnelectronics 500mA

[@peterrizk4915]

How can I use i as a current regulator i want to control the current going into a motor to comtrol its torque?

[@learnelectronics]

That is what I showed in this video. i dont understand your question.

[@jedandecko5585]

Nice and simple :) good one again. What is efficiency? tnx

[@learnelectronics]

It will vary based on voltage dropped.

[@jedandecko5585]

tnx

[@jclowersitc4866]

Very nice..!

[@learnelectronics]

Thanks

[@vvsswe]

Hello You have an incorrect link to the calculator

[@learnelectronics]

It's fixed, thanks.

[@cwebs1000]

Where is the link for the give away?

[@learnelectronics]

Its fixed now. Thank for pointing that out!

[@MalagasOnFire]

This a trusty linear regulator , low ripple , flexible applications and if you want more amps just put a higher transistor in parallel . Where is the bypass cap at output?

[@SimpleEnough2k9]

For demo purposes the bypass caps aren't really necessary unless the source is really noisy.

[@fog450]

My dream project is cv and cc using lm317 and a microcontroller to control it that would be cheap and usefull.ps like to own the multimeter

[@ErkanOkman]

👍👏

[@pigglewiggle175]

Play this on at least 1.25... this guy is slow af. He has pretty chunky fingers... imagine the stress on the heart.

[@DennisMurphey]

I build your circuit using a variable Resistor selector for R2, but it does not adjust. Can you look at my diagrams and check me out? Dennis in Virginia