Building An LM317 Lab Power Supply - Part One!

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Building An LM317 Lab Power Supply - Part One! - Ec-Projects

Рет қаралды 132,133

11 жыл бұрын

This video is about making a very simple lab power supply out of the LM317/LM350 voltage regulator!
This first part is about picking the right components, calculating values, and doing a few tests.
Part two: • LM317 / LM350 Lab Powe...
Link to parts list etc.: ec-projects.com...
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Пікірлер: 52

@SkyKing101010 8 жыл бұрын

Personally, I think you're doing a bang up job on this. I know this because I'm learning a lot. I haven't really done anything with voltage rectifiers before so this is excellent. Concerning the output ripple from the bridge rectifier; when I was in school for radio and tv electronics, during our studies on power supplies, the transformer we used was 120vrms - 24vrms center tapped, of course the four diode full wave bridge rectifier, and two 4700 uF @ 50v capicitors in parallel. It wasn't perfect, but it did remove the 60 cycle hum from the output nicely.

@EcProjects 8 жыл бұрын

Thanks! Glad you liked it :)

@WaltonPete 9 жыл бұрын

Thanks for posting your video I found it very interesting. I think your PSU design is very economical with regard to the number of components and therefore cost and should be useful to other hobbyists. I suspect that with such a relatively low power output passive cooling should be suitable, although some form of case ventilation holes would be advisable to allow airflow - even with the fan you have included in your construction.

@EcProjects 11 жыл бұрын

Hey, thanks for the comment :) The power dissipated (heat generated) by the pot is dependent upon the value of R1, if you pick a higher value for R1, less heat will be generated. With the values I used the pot is getting to about 35 degrees C I think. A few examples with a 240 Ohm for R1 (we forget about the 100 uA from Iadj) if you set the output to 12 v, The current through R1 is approximately 12/(240+2700) = 4 mA if set to 1,25 v, the current will be 1,25/240 = 5,2 mA.

@EcProjects 11 жыл бұрын

Ebay :) Just search "bread board wires". Cheap, but they don't take much current and they pick up a lot of noise.. I started using solid-core ones, they are a little better noise wise, and much better current wise. :)

@EcProjects 11 жыл бұрын

Hey, I would say that "R2=(12-1.25)/(200+30)= 0.047A =~0.5watt" Should be R2=1.25/(200+30)= 5,4mA, because since R1 is connected to the output the voltage across R1 and R2 will drop equally to the output voltage, so there should only be a 1,25 v drop :) Sounds like a good idea, I got some LM2576t-adj switch mode regulators laying around, I could perhaps make a small video, but I'm a little busy these days so it might take a while.. :)

@AIexanderHartdegen 8 жыл бұрын

I love your multimeter!

@EcProjects 8 жыл бұрын

+Alexander Hartdegen Yeah, ain't she pretty, and she doesn't complain, even though I have many other multimeters :D

@Metalloys 8 жыл бұрын

+Alexander Hartdegen EXPENSIVVVVVVE

@SkyKing101010 8 жыл бұрын

+EcProjects I guess the others just know when a girl has class.

@tugaminhoto4969 10 жыл бұрын

Very good video, congratulatiions

@EcProjects 10 жыл бұрын

Thanks :)

@heyyodog3096 8 жыл бұрын

you sound more enthusiastic than a stripper in a geologist seminar. Fuck in FUN!!!!

@jp-um2fr 6 жыл бұрын

How about the LT1083. It's a super grunt LM317 with a limit of 7.5A - all you need is a big heat sink and fan. There is a super kit available from China for £3.78, useless heat sink though. There was a great video of one being tested on KZfaq but it's gone. There are kits being made though. Iv'e made 3 and they work well.

$@frac$

@frac 9 жыл бұрын

I see you have a fan on the heatsink, but no ventilation. Do you find that to be an issue if it's under load for long periods. I would expect the interior temperature to slowly climb higher than desired.

@jp-um2fr 7 жыл бұрын

Very nice video but there are dozens like it on KZfaq. I have seen video's on KZfaq where the LM317 / LM338 can be used as a current limiter as well as a voltage regulator. I do not have the know how or confidence to marry the 2 circuits together. This would then make a proper bench power supply. I am interested in LED's and need current limitation at the m A level. Please help.

@juanmacias4854 8 жыл бұрын

Good video, thanks. I'm thinking of building a Toroid transformer from scratch, any idea where I can obtain the metal ribbon (core)?

@NovelRamadhan 8 жыл бұрын

Why not to try double channel using 12-0-12 transformation? with Vo in each other up to 9 Vdc

@kstxevolution9642 4 жыл бұрын

did you just get that voltmeter on the display off the shelf?

@DoctorThe113 3 жыл бұрын

Yes. It's off the shelf. You can get these for dollar or two from aliexpress.

@Poochie43124312 11 жыл бұрын

where did you get the jumper wires for your bread board?

@marcdownton4769 9 жыл бұрын

Do you have a schematic or bill of materials?

@albertdebobes8330 6 жыл бұрын

Great video! I really wanna try to do something similar :) One question though, the box/casing needs to be grounded or it is not necessary? Thanks!

@EcProjects 6 жыл бұрын

It's best to ground it. But it's pretty safe when using a transformer.

@albertdebobes8330 6 жыл бұрын

EcProjects Thanks for the answer!

@vaibhavbvs287 8 жыл бұрын

It would be great to have links in the description to every parts used in this project.

@EcProjects 8 жыл бұрын

Oops, I was supposed to have a link to my website page, which has all the information. I added it now, thanks for pointing it out :)

@CrabtreeGuitar 8 жыл бұрын

For safety should one consider a "bleeding" resistor in parallel along with the capacitor at the rectifier? I'm a student and don't know the terminology for this.

@CrabtreeGuitar 8 жыл бұрын

I'm referring to add a resistor in parallel to the capacitor at minute 3:16

@EcProjects 8 жыл бұрын

+Ronald Crabtree If the voltage on the secondary gets higher, then I would certainly add one in, but it doesn't harm to put it in anyway !

@PatchworxStudios 9 жыл бұрын

omg i have the absolute same analog ampmeter lying around here. It was from an antique audioamplifier xD.

@EcProjects 9 жыл бұрын

PatchworxStudios Hmm, I forget where mine is from :)

@alaskanamber1 10 жыл бұрын

Great video, thank you. I am interested in building one but I need 20A, Any advise?

@EcProjects 10 жыл бұрын

You 'can' do that by putting many in parallel (there is a schematic for that in many of the LM317 /350 datasheets).But I would recommend a switch mode power supply instead, if you are not making some super precise test equipment.The heat generated by the LM317 / 350 (or any linear regulator) will be quite serious at 20 amps.

@SylwerDragon 9 жыл бұрын

EcProjects That is why you will use power transistor for added current.

@spankbutt123 9 жыл бұрын

Why not mount the regulator to the chassi and use that as heatsink?

@EcProjects 9 жыл бұрын

spankbutt123 Yeah I could have done that.. The reason is that I made the supply long time before I made the case. Originally I had it in a thin steel box.. So I just threw everything into the new case.. :)

@DerKeineAhnungMan 9 жыл бұрын

i stay with my dual OP & BD249 power supply. can get up to 12 amps out of it :) i want to see a lm317 after flowing 12 amps through it...

@EcProjects 9 жыл бұрын

DerKeineAhnungMan Hehe, yeah wouldn't be much left to see :D

@DerKeineAhnungMan 8 жыл бұрын

yeah but he is using a lm317 and not a lm338t

@EcProjects 11 жыл бұрын

If you use the same circuit as I showed in the video * :)

@seansysig 7 жыл бұрын

Curious what would you use 12V negative on?

@pawEHO 7 жыл бұрын

-12v are oftenly used in audio amplifiers

@dedskin1 5 жыл бұрын

fans and motors are very noisy , i wouldn't introduce a fan in something to not introduce noise , i would leave it out to not introduce noise , best available power regulators such as in PCs cant handle noise from Fans , when i used a fan to check my voltage regulator build it was noise galore to the point of thinking i didnt make it correctly , should be stabilizing that output, then i build a simulation of it in Electronic circuit software and observed identical behavior , so my conclusion is that motors introduce noise and hardly anything can be done about it .