Trouble with LM317?

Im having trouble in finding a heatsink for an LM317M chip and was looking for suggestions on where to find one that would be good for it. this is the datasheet for the chip...it should be the DCY Package (top view) http://www.ti.com/lit/ds/symlink/lm317m.pdf

Question by diabloboy   |  last reply


How to set voltage on LM317 adjustable voltage regulator? Answered

How do you set the voltage regulation on an LM317 to 5 volts?

Question by Xixfas   |  last reply


more output current with LM317 ?

Hi, for some time I have been wondering if I can make LM317 to output more than 1.5Amps. After many hours of searching I found that I can achieve this in 2 ways. The circuits are in LM317 datasheet which can be downloaded from here : http://www.ti.com/lit/ds/symlink/lm317.pdf 1- By using a transistor with LM317 (page 16) . 2-By using several LM317 regulators in parallel and using TL080 (page 15). Second one seems better IF load is equally divided between regulators, it also has the benefit of producing less heat when  high currents are drawn. My question is: will the second circuit (LM317s in parallel) work and output more than 2Amps? is load equally divided between regulators in this design ? can I replace TL080 with another IC ? By the way, there is a circuit in page 12 called "tracking preregulator" , what is the purpose of this design ? PS. I know there are switching regulators which output more current, but I'd like to experiment with LM317.

Question by ehsan_zt   |  last reply



What is the max input current for the lm317? Answered

I am having trouble understanding the datasheet. Is there a max input current for the lm317? If so, what is it? I want to supply 4A input current to it from a laptop power supply. http://www.fairchildsemi.com/ds/LM/LM317.pdf Thanks.

Question by Dmxspider   |  last reply


Please help me with my LM317-T LED driver.

A while ago I bought a 10W 12V LED on line to see if I could build a small projector. Then somewhere, I hear you need to build a driver for it, otherwise you WILL blow the thing. So I start googling and tinkering and find a few basic formulas, P=IV, ==> P/V=I ==> 10w/12V=0.833A So I need to get a current of 833mA at 12v to run this light, next step. According to most sites, the cheapest way of doing this is with a simple LM317-T Regulator. The ADJ voltage on this is 1.25v, so, V=IR ==> V/I=R ==> 1.25v/0.833A= 1.5 Ohm. So I pick up a few regulators and a fist full of resistors at my local electronics shop, dust off an old soldering iron and thow it all together. Then I plugged it on to a 12v 1.0A Power Adapter. I'd heard the 317 had a Vdrop of about 3 volts, so I took some readings to make sure everything was ok. Got 620mA between the Power/LED, the LED/LM317, and LM317 to the Power, all is good. Voltage was 12.13v across the Power, 9.20v across the LED, and 2.91 across the LM317v (0.95 over the resistor). All the numbers looked fine. Here's where it got tricky. Knowing the LED was rated for 12v, and the drop over the LM317 was ~3v, I dug up a 15.2v 1.2A Power adapter, and plugged that in instead. When I took the readings however, my current was up to 810mA, but the voltage was still down at 9.56v. The Power adapter was at 15.20v, and the 317 was dropping 5.67v. This is the bit I don't understand. How can I get my volts back? I know the LM317-T regulates its current via the resistor, but I'd assumed the voltage was dependent on whatever you plugged in, minus a constant 3v drawn by the regulator. This assumption is obviously wrong. Is there a way I can get the voltage back?

Question by Fuzzy3D   |  last reply


LED driver based on LM317 gives more voltage than required? Answered

Hi, I tried to run a 1 watt led with the LM317 in constant current mode. Since the led required 350ma currrent, I used a 3.3+1 ohm resistor in series across the Vout and ADJ. So my resistor series was about 4.3 ohm which should deliver about 290ma current to the led. The driver was based on https://www.instructables.com/id/Super-simple-high-power-LED-driver/ When powered up, the current across led was around 290ma but the voltage across the led was 4.33v whereas it should be between 3.0-3.6v according to the led datasheet. What am I doing wrong? Is it safe to run the led at 4.33v ? It was getting hot.

Question by ethanol47   |  last reply


Is there a way to work out how long this motor would run? Using LM317?

Im running this Motor (see picture) Using a 6V 1.2ah Lead acid rechargeable battery. I have it connected as per Picture 2 - Using the LM317 Voltage regulator, with 4.3volts going to the Motor - which is working perfectly. (Thanks to Steveastrouk ) I am trying to find out if it is possible to work out how long (Time wise) this motor would run before it stops working. ie, the battery gets too low (below 4.3v im assuming)  etc? I don't know too much about the LM317, so any help would be greatly appreciated, if there is a formulae or way to work it out?

Question by MrGreenFingers   |  last reply


Bob Pease is dead

Bob Pease, the Analog design engineer who, while working for National Semiconductors,  developed devices like the LM317 regulator amongst many others, died yesterday in a car crash in Silicon Valley. Bob was a legendary figure to any engineer working in the analog domain. He died leaving the memorial service for another legend, Jim WIlliams of Linear technology, who died of a massive stroke last week. Bob was one of the nicest guys in the business, and mentored dozens of engineers in his long career.

Topic by steveastrouk   |  last reply


I need help with short circuit detector / electronic fuse. Answered

So I'm making a variable power supply with an LM317 and I've decided to add a short circuit protection, I know the LM317 has an auto shutdown feature but I thought this would be a nice feature and it would allow me to leanr more about circuits. The short detector is quite simple, It's a PNP transstor connected to the output. When the output is shorted the LM317 can't supply enough current and the load sucks everything it can, so it sucks the charge of the capacitor, causing the PNP transistor to activate and turn on the relay and the LED. This connects the PNP to ground, making it be permanently oopen until the circuit gets reset. It works flawlessly from 16 to ~9 volts, but I go under ~9v (I don't know why) the PNP activates and the relay flickers very fast, I tried several things but none fixed the problem. I have plenty of PNP nad NPN transistors so if you can come with a better and more stable design I would be able to try it, I'll be all the afternoon trying if I can figure this out and posting some updates. Here's a video of how I want it to work. https://www.youtube.com/watch?v=1nVzUUYPm3w& Look at the image for more information. Thanks in advance.

Question by Victor805   |  last reply


How do I tweak this voltage regulator? Answered

I pulled a power-board out of a 'phone charger (pic) The transformer and bridge rectifier have been removed and it's powered from a 9V motor. The charger says: Input 230V~ / 50Hz  / 40mA / 9.2VA Output 7V / 300mA / 2.1VA I'd like it to regulate to 5.0 V (for USB devices) - what do I fiddle-with? L

Question by lemonie   |  last reply


How do I set the lm317 voltage regulator to only output 1.2v? Answered

I have a 1.2v regulator (lm317) and I have a circuit that is producing about 3v. How do I connect the two together so that I have a 1.2v output?

Question by fullcircle   |  last reply


Lm317 to a 48v ac powersupply, or how to lower the voltage 10 v. Answered

So i have this transformer that puts out 48v ac. I want to make a variable power supply, and it should put out 7 or more amps. I could use lm317 with a bypassing transistor, but lm317's maximum input-output voltage differential is 40v,  so what should i do? If anyone has ideas how to lower the transformer's voltage 10 volts that would be great.

Question by jukees   |  last reply


Why did my lm317 stop working?

I am building an lm317 power supply that has a 510 ohm resistor and a 10k potentiometer. For power I have a 12v 1A wall wart (really more like 14-15v ). I built it on a breadboard and then from there moved it to a pcb (the pre cut kind from radio shack) and everything went fine. However when I tested it before i closed up the project box, it would only supply about 14.06v to 15.22v. Im not sure what is wrong, all the connections look fine and nothing really changed from when it worked.

Question by tim127   |  last reply


would like to know where to wire the 10k linear potentiometer to the Lm317

I'm trying to build a Led Constant Current driver for my led grow plants but I'm stuck on where i would solder the 10k linear potentiomter on the LM317 By the way this is what I'm using 10k linear pot 1kohms fix resister 2.2ohms resister LM317 can someone please draw in color code where i would solder the 10k Pot wires to the LM317  please really appreciate it thank you

Question by lex76   |  last reply


Voltage regulator? Answered

Does a voltage regulator IC (e.g 7805, LM317 etc) still draw current when there is no load?

Question by .Unknown.   |  last reply


Laser Engraver Circuit Help

Hello. I am making my own laser engraver out of 2 DVD burners just like Groovers version. I have some questions about the circuit that im going to use: I have seen the typical LM317 circuit for laser diodes (LINK HERE) I dont completely understand the circuit Groover made. He says that he uses the LM317 circuit over, but it does not look exactly the same. Can someone explain to me a bit why his values on the resistors/capacitors etc. is so damn different? (Though he also use relays and stuff for outputs for fans ) (LINK TO GROOVERS CIRCUIT) I made my own circuit that uses the typical LM317 circuit over, but will my circuit work fine? (Instead of the battery in the circuit, I will connect the Voltage In-ping on the LM317 to my arduino, but not exactly sure where to connect it on the arduino since i need about 7.5 V in, and not sure if the arduino got a pin that can output that much?) (LINK TO MY CIRCUIT) Thank you for your reply!

Topic by aborge   |  last reply


fast and easy way to get 3.3v from 5v without a lm317? Answered

I got a dvd player but the power supply was missing. i can get the 5v and the 12v, but other than a lm317 (which i dont have) i cant get 3.3v. ive looked at all sorts of things to try and find a 3.3v regulator, but everything i have searched up lead to several misleading results. so i was wondering, what value resistor could i use to get 3.3v from 5v or what devices could i look in to find a 3.3v regulator? i have several computer motherboards, a bunch of cd drives, a couple hard drives, etc. please help! thanks in advance,           zack247.

Question by zack247   |  last reply


high current adjustable power supply? Answered

I want to run my ps2 in car, Any circuit to drop 12v to 8.5V at 6amps the lm317 circuit is not powerful enough

Question by ARJOON   |  last reply


How to configure LM317T to deliver 5 amps?

Hi guys, I'm new to the site. I wonder if someone could help me resolve my problem. Well, I'm trying to build a Laptop AC Adapter, but I can't get these components right now: -A Transformer -A voltage regulator other than LM317T and I have no experience with other ICs. So I'm using a DC to DC converter. The input power supply is a Z12 Lexmark printer AC adapter. It gives a DC output current of 830mA under 30 volts (actually it's 37.5 volts, I've checked this with my multimeter). However, the output I would like to get is 4-5 amps under 19.5 volts. I would like to mention that I've already given it a try. But the output current I've got wasn't enough to feed the laptop. I've used an LM317T and adjusted the voltage with a 6.6k resistor and a 47k potentiometer down to 19.5 volts. If there is a way to boost up the current with a joulethief or using a set of transistors or parallels LM317Ts, please tell me. Also, I hope that you give me the part number of all the components to match up with the LM317T because I must use this type of regulator. Thanks for your help and please consider my situation.

Question by junkrecycler   |  last reply


Variable Voltage Regulators with + and - 12v input? Answered

Hi, I have put one of these together for an ATX power supply and have come across something that I might be getting wrong.... In mocking up the LM317 circuit in breadboard (standar one found everywhere on line and on the LM317 pages), I have got the thing metering -11v to +11v??? I am using one of the black ground wires of the PSU on the black side of the volt meter, but cant figure out why I am not just getting positive voltages??? Could the diode be faulty? Or is this in fact correct? Any help appreciated...

Question by lone_viper   |  last reply


Help me step down AC voltage without a transformer?

Hi again. Well, the title explains everything. The goal is to make a 65W power supply the simplest way. I have capacitors and diodes, and I'll desolder other components if necessary. Just, if someone can give me instructions and detailing a little bit. May be you can post some schematics or useful links. I've already created the circuit schematic but I would like to see yours first. I will post mine later but it doesn't include the values of the components and maybe it contains some errors. It was enough hard for me to draw it. I'm no professional afterall!

Question by junkrecycler   |  last reply


Homemade power supply problems

I am trying to build a variable power supply using a LM317 variable voltage regulator. When connected to no load, i can get a sweep from 1 volt to 15 volts. but when a load (small pager motor, laser diode) is connected, i can only get up to 4 volts, and about 12 milliamps of current. Help!

Question by wii552   |  last reply


connect a 3 WATT LED to a 6 VOLT 4.5Ah RECHARGEABLE BATTERY through a LED DRIVER (LM 317) CIRCUIT????

HII ALL ,,,WHAT IS THE CIRCUIT TO CONNECT A "3 WATT LED"  to a 6 volt 4.5Ah rechargeable battery through a LM317 DRIVER CKT??? I USED RESISTORS BUT THEY DISSIPATED MUCH MORE POWER THAN I THOUGHT??

Question by sbdash11391   |  last reply


Orange pi's 3.3V on board regulator

Hi everyone, I've set up a mediacenter with openelec on my orange pi PC. I've put a large heatsink on cup and rams and a small 5V 0.15Ah cooling fan. With two switches I am able to switch it on and off and choose between 5V or 3.3V alimentations from the GPIO. The 3.3v is intended to spin that fan not at full speed to reduce noise while watching film or listening to music with the mediacenter. I left the PC all the night open downloading torrent, and the morning later the fan wasn't spinning anymore. I powered off the system and used a day later. The fan were at that moment working. So my question are: Is it better to put an external voltage regulator (lm317)? Anyone can explain what happened? As I recently discovered that with zener diodes we are able to clamp the voltage to a specific value (if putted in the "opposite" direction, I guess), I was thinking if it were possible to use one of them in this case.

Topic by BBQ Bee   |  last reply


Could i use pwm to vary voltage for a benchtop power supply? Answered

I wanted to create a variable benchtop supply from a computer atx supply. Could i use a MOSFET with an arduino to vary the voltage coming from a 12v power supply? Initially i wanted to use a LM317 but since that would be inefficient. The mosfet in question is IRF540N Here is the circuit diagram

Question by qwerty156   |  last reply


High current variable voltage from an atx psu

What would be the most simplistic way to draw up to 10a on an atx PSU using variable voltage controlled by a potentiometer? I've looked at a few diagrams using the LM317 but it is limited to 1.5a. The only other VVR I can find is the LM350 but is still limited to 3a. Any ideas? I was thinking of stacking an arrey of LM350s in parallel but this doesn't seem like a viable answer.

Topic by andrewlapham2010   |  last reply


WHITE LED LIGHT PROJECT

I JUST JOIN THE COMMUNITY RECENTLY.I AM FROM SOUTH AFRICA.I HAVE A PROJECT FOR LED LIGHTS,IT CONSISTS OF 24 WHITE LEDs IN PARALLEL AND I TESTED IT WITH 4 AA(1.5) BATTERIES(6V) AND IT WORKED FINE,BUT I TREID TO DESIGN A 6V REGULATOR SO AS TO USE IT WITH SOLAR ENERGY USING 7Ah BATTERY.I USED LM317 AND OTHERS BUT IT KEEPS HEATING UP EVEN WITH AN EDEQAUTE HEATSINK AND SOME WHERE FRIED,ANY SUGGETIONS,CIURCUTS IN SOLVING MY DALEMMA

Topic by temba   |  last reply


How to preset current regulation & short circuit protection ?

Found this awesome diyr Linear power supply design with voltage & current controlling- Foe more details--http://electronics-diy.com/power-supply-lm317-2n3055-0-28v-6-8a.php 1>Since it has no short circuit protection apart from the fuse,then how to preset current just like bench power supply by shorting the the leads ? 2>Without short circuit protection will the  2 two 2N3055 blow up ? 3>Please assist that what should be done for the modification.

Question by Dimitrioptimus   |  last reply


3.3V voltage regulator for diy "bare-bone" arduino?

I would like to use whether six AA or one 9Volt external battery for a diy "bare-bone" arduino* (*just the 328p atmega, 8MHz oscilator, capacitors, resitor, LED) & tested LM317, LD1086, LM1117 voltage regulators (it's a "budget" project – hence didn't try any step-up/step-down switching regulators though they seem to be the best solution ...); ------------------------------------------------------------------------------------------ SUITABLE POWER/CURRENT? can i "simply connect" any of the regulators (incl. the necessary resistors/capacitors according to their datasheets) or do i need to add resistors to reduce their current in order to not "over-power"* them? * according to the values i measured (i am a novice to arduino's power management … could have made mistakes whilst measuring) LM317  =  ca. 2A @ ca. 3.3V with 100 & 160 Ohm resistors LD1086  =  ca. 1A @ ca. 3.3V with 100 & 160 Ohm resistors LM1117  =  ca. 1A @ ca. 3.3V without resistors according to dataheets/descriptions of several arduino boards (but i might have misunderstood – this might not have any impact on the power source …   ) ------------------------------------------------------------------------------------------ TRYING TO PROTECT & REDUCE POWER FOR ADDITIONAL FEATURES ... LED to indicate that there is power flowing … hoping that this reduces the power consumption: - a 20 KOhm pullUp resistor ? Protect from charge … hoping that this protects the circuit from capacitors' stored charge: - 2* 1N4001 on voltage regulator? ------------------------------------------------------------------------------------------ i look forward to your advice …

Question by marc_is_curious   |  last reply


Constant current power supply, will this work? Answered

Hi,  i found some parts in an old computer, since i could not get my hands on an lm317 This is what i used, 1 x L7805cv voltage regulator ( from an old computer) 2 x 660nm 3 watt each running at 2.2v 0.700mA 1 x 10ohm resistor connect to ground and output 1 x 12v 1.5a power supply I can run 1 or 2 leds and they are pretty bright, only the L7805 gets hot but i assume thats normal. What do you think of this setup, will it last? See pictures Greets JB

Question by MistaMasta   |  last reply


12 volt stabilizer/regulator (high current)

Hi, I need something that's able to regulate the car voltage that vary from 10.2 to 14.7 (with lower voltages at startup that's not relevant)  to a stable 12v with a tolerance of 1-2% at high current (need at least 35A but I don't want to full load it too often then 40A would be better). I saw something like a lm317 with some external transistor that's able to put out something like 15A but it required a 30V input and it was a too much low current. can you link me an image of a circuit that's able to do what I want?

Topic by andry08   |  last reply


Fan needs 12 volts at .44 amps. How can I limit the current to .44 amps from 2 amps, without losing the 12 volts? Answered

I am trying to power a fan that needs 12 volts at 440 milliamps. I have a wall-wart transformer that is 12 volts, 2.0 amps, and I many components. I have thermal compound,  heat sinks, resistors, 12 volt and lm317 voltage regulators. So, how can I limit the current to 440 milliamps from 2.0 amps, without losing the 12 volts? Also, I tried a resistor at 33 ohms and it burnt out. Thank you, Jeremy (Please note: I am teaching myself electrical engineering, I have not taken physics yet. My knowledge is based on sever books, web resources, and hundreds upon hundreds of youtube videos)

Question by JBronen   |  last reply


Alkaline Charger

So, I want to try and build a charger for alkaline batteries with an Arduino.  I'll be using it to recharge 9v batteries. What I want to know is: What would the optimum charge current/voltage be?  Should I pulse the charge current? How do I detect the state of charge? How can I get ~1.6v from the arduino to charge an AA? Can I use PWM 5v? And any other useful info you may want to add. I have a ton of parts/shields/etc for arduino as well as components.  LCD's, IC's, LEDs, diodes, resistors, crystals, etc. Would also like to do a battery diagnostic utility to test health, resistance, charge, etc. Can anyone help? EDIT: So I made a quick circuit and sketch to charge an AA battery to 1.6v, using an LM317 adjustable voltage regulator. As os so far, it is working.  Now I need to figure out how to make a voltage doubler. I'm thinking something like 40-50 mA output at 10v. I have an LM324N quad op amp chip as well as one of these. How could I make a doubler circuit?

Topic by LiquidLightning   |  last reply


How to make power bank with 8 rechargable AA batteries?

I'm a nobody at electronics, electricals and stufs. well i have some rechargeable batteries for some reasons,. 2 of my friend has a portable power bank for their phone. then curiously thinking if i can make that kind of stuf.. (DIY),.. if it possible please help me make this... my AA batteries is 1.5V with 500mah of power if i'm right. , then multiply by 8 so that will be 12V with 4000mah of power? right?. then i want this to charge my phone... recently searching i need to drop the voltage to 5, because if not, my phone battery will or might explode., then my phone will be damaged?.. so i need to make a circuit,, then that my problem, i dont know any thing about resistors and things like LM317, just i don't know anything about that.. i need it be able to be recharge and charge my phone, so here's another question, expect the wee did make something like that, then how will i be able to charge it?, it's 12v right from the inside? right?.. that all, hope we can make something like this,, if there's a related post, which has been already answered, if this is not possible.. That all.. Advance Thanks for helps... 

Question by ZoneOne26   |  last reply


Trying to run my sony Cybershot from an external 12V supply. Need help

Background: I am currently trying to build a housing that will turn my Sony DSC W-55 Cybershot Camera into a time lapse camera (Automatically take a photo every X Seconds for an extended period of time). I have already built the enclosure that houses the camera, circuit board and actuator that presses the shutter release button ever 15sec. (Adjustable). Pictures below Problem: I Need to run the camera for very long periods of time (current baseline is >8hr, but indefinately would be nice). The camera uses a Sony G-Type Li-Ion Battery that does not provide the runtime I need for this application, so I am trying to hook the camera up to an external supply. The battery has three terminals as follows [+] = ~3.9V    (No surprise here) [C] = 3V         (This is weird) [-]  = 0V I accepted that the extra terminal was strange, but figured it would not be hard to simulate. I used an LM317 Adj. Voltage regulator to simulate the 3.7V [+] Terminal and a voltage divider off of the 3.7V bus to get the 3V required for the [C] terminal. I double checked everything and plugged it in with no success, the camera will not turn on. My question is, what smarts are in the battery that I need to simulate, or is there something wrong with my current set-up. Any help will be appreciated. Thanks, John

Topic by John Culbertson   |  last reply


Why do my lm317T and lm78XX regulators die so easily? Answered

While using my last 7808 voltage regulator as nothing more than a voltage reference for a breadboarded linear power supply design, I noticed that after a few small modifications, that the 7808 was no longer outputting 8V, and was instead floating 14.8V (kinda close to the +15V supply rail). At no point did the regulator overheat, and it was simply connected to the a 200K potentiometer to ground and a noninverting input of a LT1112. In the past, I have killed at least 3 LM317T regulators in my velleman 3-in-1 lab thingy, (it is a relatively simple circuit and was the first board I have ever fully reverse engineered.) The heatsink never did get too hot, but I used to always connect heavy loads to it that caused the overload lamp to come on. That LED was basically in series with a large resistor to the input of the LM317 so when the LED has enough bias voltage, it comes on when around 1A is being pulled. Anyways, I have killed countless other small 78xx regulators, one way or another, and even made some of them literally explode right away. (generally by getting the pinout wrong.) I blow up these regulators so commonly I even have video evidence lol! click to around 3:30 for the FAIL! https://www.youtube.com/watch?v=lPHHvVTVbwM So is it just me and my luck, or are these regulators which supposedly have all sorts of thermal protection, current limiting, and short circuit protection just not as rugged as they seem they should be?

Question by -max-   |  last reply


Please suggest me a charging circuit for 12V 7.2 Ah lead acid battery without application of transformer

                                     I am using 12V 7.2Ah Amaron Quanta lead acid battery for an Emergency Lamp. I am using the following charging circuit which is attached with this post. In this charging circuit, 230 ac voltage is given as input to the 16-0-16 transformer. The output of transformer is filtered through rectifier diodes and then given as input to the LM317 of charging circuit. As of now transformer is needed to step down the ac input voltage. I need a charging circuit without a transformer. So kindly suggest me a circuit which consists of input rectification without a transformer. Please suggest it with a moderate cost. And also I need one more clarification. I am using "Constant Voltage" - trickle charging method to charge the battery. I am using a load of 2 lamps of total 110 W lamps which stand for around 50 minutes of full charged battery. The lamps will cut-off at 9.5-9.8 V. Then it takes around 16 hours to make the battery full charge. Could you please confirm me if I can charge the battery soon (min 6 hours). Is so at what rate I should use the load. Please help me in this situation.                                      I mention the website link which I am currently using for charger circuit.                                     http://www.circuitstoday.com/lead-acid-battery-charger In this circuit, I am using a 16-0-16 transformer to convert the line voltage of 230V ac and bridge rectifier diodes to convert it into dc. Please suggest me a circuit without the application of transformer to convert 230V ac to dc.                                         My mail id is tvibakar@gmail.com. Thanks, Thomas.

Question by tvibakar   |  last reply