Questions tagged [lm317]

3-terminal adjustable linear regulator

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1answer
761 views

Why Lm317 burnout and the potentiometer sparks?

so I tried to make a power supply using Lm317 and it works fine when i used a 12 v transformer but when I used a 9-0-9 transformer like in the picture,when i turn potentiometer, it sparks and then ...
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0answers
311 views

DC 30v Adjustable PSU using Lm317

This is the adapter i got in My hand I need a cheap diy stable circuit for making an Adjustable PSU using LM317 Voltage Regulator. I got a adapter with output power supply of DC 30v 400mA. I need a ...
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2answers
2k views

Can i use 47uf instead of 10uf in LM317 Adjustable voltage regulated circuit?

Please refer the images above for the circuit, my question is can i use 2x47uf cap instead of 2x10uf cap in the circuit, since i dont have any 10uf cap in my hand, Thanks.
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2answers
205 views

Power Supply for xl6001 12V Switching LED Driver

I have 2 nos 7W LED Modules, each of which are fed from a separate XL6001 based LED Driver. The DC power input to the drivers is from a 12V, 7.5AH SLA Battery. The LED driver takes 12V DC from the ...
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4answers
7k views

Purpose and explanation of resistor near output of LM317, high-current, adjustable-regulator circuit

I'm trying to make a high-current, adjustable-voltage regulator using LM317 data sheets. Specifically, I am using the schematic below. So, what is the point of the resistor related to Note A? Is it ...
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2answers
233 views

Seeking means of maximizing energy use from LiIon battery supplying a 3.3V load

I have a device that operates with 3.2 V MAX, and I wish to power it from a standard 3.7 Li-Ion battery. A fully charged battery=4.2V. I used a simple LM317 circuit to drop voltage to 3.2V and it ...
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0answers
119 views

LM317 thermal cutoff for voltages more than 37V above ground

I'm using the LM317 and LM337 for regulation of positive and negative high voltage rails. I noticed in the datasheets (LM317, LM337) that they have a thermal cutoff, but I wonder if this could ...
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2answers
436 views

Connecting 12V fan to LM317 DIY PSU circuit

I am working on a simple adjustable DIY power supply using an LM317 voltage regulator. J1 in the image below represents the transformer rated at 18VA, which rectified produces about 25V DC. The output ...
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3answers
2k views

How to make 5v DC UPS Circuit?

My objective is to build a Circuit which will draw current from Solar Panel, recharge a battery as well as run the load even if voltage from solar panel goes too low. I have made the following ...
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1answer
138 views

Needing Help On Lasers

I hope you can help me! I’m going to categorize this into A) B) C) Recently just bought a NUBM08 Nichia Laser Array and need to know how to get this boy working! A) So for this Spec Operating ...
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3answers
2k views

LM317 PSU - Huge voltage drop

I have a small demo breadboard circtuit based on this design: I use this transformer, it's connected for 115V input on primary, and 2x24V output, and I'm using only one of these outputs at the moment....
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1answer
1k views

What are the disadvantages of using a laptop power supply (into an LM317) as a bench power supply?

I have a Dell laptop charger, which claims to output 19V, 1.58A . Is there any value in re-purposing this for hobby electronics? I'm tempted to do something quite crude, such as feed an LM317 from ...
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2answers
3k views

Will this variable voltage supply with variable current limit circuit work?

I want to make a variable power supply with variable voltage and current. Recently made a variable voltage supply using LM317 but I couldn't control the current so I want to try combining it with an ...
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2answers
1k views

LM317 explosion

I was trying to make 1A dummy load using lm317 (didn't intend to use it,just trying!). So, I connected the circuit as shown : I put 1 ohm resistor as a load and another 1 ohm resistor instead of R1, ...
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1answer
314 views

Wrong pin configuration of LM317 and LM337

I have a problem with the circuit i was given it seems that i made my circuit connection wrong. the pinconguration of LM317 and LM337 are on the left picture with 1-2-3 while i am suppose to connect ...
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1answer
3k views

LM317 Constant Current Battery Charger Question

LM317 constant current charger are quite popular as it seems. I made one for my 12v 7Ah Lead Acid battery. I used a 2.2 ohm 10 watt resistor and calculated that it would give a decent amount of ...
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3answers
3k views

Why does LM317 burnout when output is shorted in this case?

LM317 voltage regulator has internal short circuit protection alongside with its thermal overload auto-shutdown, but in the circuit below it will simply burnout when the output is shorted. And its ...
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1answer
1k views

LM317 vs series diode (1N4007) as voltage regulator?

I am using the SIM900A GSM module which requires 3.2V to 4.8V with max current draw of 2A. In my board, I have a 5V, 3A supply which will be used to power the SIM900A. Generally, in my search I ...
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1answer
759 views

Need help with LM317 voltage regulator circuit

I am new to electronics and not quite sure how to debug a circuit. I created a simple regulated power supply circuit as following using LM317 voltage regulator. simulate this circuit – ...
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1answer
2k views

LM317 Maida Style regulator

I need to build a regulated 48VDC ~1amp power supply. I have two transformers on hand: One with a 36VAC secondary which would give around 51 volts DC once rectified The other with a 44VAC ...
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1answer
1k views

multi-tap transformer relay for LM317 tips

Example circuit: Since LM317 is a linear regulator it will get very hot when i try to draw around 1 amp @1.25v with a 24v input. The transformer i have at home have these taps: 24v 12v 5v Is it ...
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4answers
13k views

Making LM317 output voltage adjustable down to 0 V

I want to design a variable voltage regulator that will get from it`s maximum output (lets say 10V) down to 0V (or very close) considering the input as regulated 12V (from a PC power supply). All the ...
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1answer
108 views

Input voltage from supply dropping when connected to an LM317

I am having an adapter which can give output of 5V and 1Amp( I have tested it). But when ever I connect this adapter to Vin of an LM317, the input voltage is itself dropping to 2.5V.
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1answer
2k views

When to use LM317 vs LM2941CT? [closed]

A seller sent me by mistake a bunch of LM2941CT. I checked the specifications and I see they are interesting, especially given I'm running out of LM317. I would like directions for choosing one over ...
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1answer
596 views

Need some help about why this circuit (PSU) isn't working

Trying to make a current limiter for my LM317 power supply. This is the complete circuit: I found the current limiting circuit on the web, I'am powering this circuit from a 12V 20A switching lab ...
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2answers
560 views

Voltage reference for an OCXO

I have a no-name OCXO with pins marked by seller (VCC, GND, RF OUT, Vadj). I have checked its output frequency against rubidium oscillator using the following method: I connected them both to ...
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3answers
13k views

Two LM317 Based Voltage and Constant Current Regulator Circuit

I have read some articles on on the following circuit. I was wondering if I can create such a Voltage and Constant Current Regulator for my Power Supply or not. My Question is - is this circuit ...
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2answers
1k views

LM317 - Getting the lowest possible Vout

The LM317 can produce a Vout from 1.25V to 37V. I have a small piezo pickup I'd like to step down to as close to 1V as possible. The formula for the LM317 is roughly Vout = 1.25(1 + R2/R1). Can I just ...
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1answer
148 views

Voltage Regulation Based on Ratio of Source Voltage

I'd like to use the ubiquitous LM317 to regulate voltage down to 1/3 of the source voltage. Reason being, I'd like to retain the voltage information of the source (li-ion batteries). (source: reuk.co....
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1answer
730 views

LM317 to charge a NImh battery from usb [closed]

Hi want to charge my 4000 mAh 1.2V nimh cell battery simply, I do not use them very often. So I wanted to plug this kind of voltage regulator which I think is like that : https://en.wikipedia.org/...
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2answers
3k views

LM317s in parallel connection

Is it possible to connect 3 LM317s in parallel to get upto 4A of current output ? I need 4A but I'm not able to figure out any other possibility. Is there any other possibility to achieve this ?
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1answer
79 views

Voltage Amplifier

I have a 3.7v battery as a power source. I want to make a circuit in which I can regulate the voltage between the ranges of 2.5-5v. I was able to build a circuit with a LM317. It allowed me to trim ...
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4answers
4k views

Variable output LM317 power supply circuit - potentiometer burning

I have just finished making my first power supply. But when I tried to use it the potentiometer was burned. I tried different fixed resistors and all the resistors below 10k ohm gets burned. What ...
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3answers
3k views

Charging circuit for bulk 1.2v 1200mah ni-cad batteries

I am seeking advice about how to construct a charging circuit for 1.2v 1200mah ni-cad batteries. I have around 60-70 of these batteries and I want to create a bulk charging circuit so I can charge 5 ...
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3answers
25k views

Smartest way to use current limit using LM317?

As i understand, using this circuit: Will cause the current to go right through the POT and resistor, which will generate a lot of heat. Is there a better way to use current limiting with LM317 ...
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5answers
592 views

What am i missing for this to work? (Zener Diode)

Since the zener breakdown voltage is set to 5v, i actually thought that the voltage would be 0, since it goes directly to ground, I just wanted to try a "simple overvoltage protection". How is it that ...
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2answers
11k views

LM317 Dropout Voltage

The LM317 Data Sheet doesn't appear to specify a dropout voltage in the table of electrical characteristics. 1.2V - 1.3V sounds about right for the dropout voltage; is "reference voltage" an alternate ...
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1answer
2k views

Lab Power Supply based of LM317 (Project)

I'm pretty new into electronics, But I do this mostly for educational purposes. Even if there are cheaper/more effective ways to build a power supply, I want it to be based of the LM317. This ...
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1answer
3k views

How to improve load transient response of an LM317 voltage-regulator powering an audio amplifier?

I am building a voltage regulator circuit for powering a pair of mini-speakers (about 3-5W) with built in amplifier and an old mp3-player/FM radio. The power source is an old mobile phone charger (...
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3answers
9k views

LM317 µA Constant Current source possibility?

I want to create an adjustable µA Constant Current source using a LM317. It is typically stated to have a 5mA to 10mA minimum current for proper regulation. The On-Semi version linked above shows a ...
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1answer
789 views

How much current will LM317 pass in this circuit?

The formula for the output current of a LM317 is: In this schematic, what will the output current be? simulate this circuit – Schematic created using CircuitLab MY approach: I thought R in ...
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4answers
781 views

Powering multiple white LEDs in parallel [duplicate]

Recently the idea struck my mind, that I wanted to build a simple but useful emergency light which can run off of any USB port (the specific use case would be to power it from an USB power bank). For ...
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3answers
636 views

LM317 lower voltage limiting

Let's say I want output voltage from LM317 in range from 8V to 15V. What circuit do I need to built? I understand perfectly how to set upper voltage range (1 x resistor + 1 x pot), but how do I set ...
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1answer
3k views

How do I build the current regulator circuit referred to on the LM337 datasheet?

What I would like to accomplish: I am trying to add current regulators into a home built dual rail linear regulated power supply. I previously asked this question about transformer fusing and ...
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1answer
110 views

Mirroring constant current

I'm trying to draw a constant 60mA from a battery but I get a draw that is too high with the following setup. Does anyone know what I'm doing wrong? Regards EDIT: Sorry I added the wrong measures. ...
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1answer
994 views

Why is LM 317 regulator getting hot? [duplicate]

I have just made up a adjustable regulator circuit using the LM 317T, the input is approx 33 V, and output 16 V, but the LM 317T when cold regulates at 16 V, but once the LM 317T gets very hot the ...
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2answers
398 views

LM317T Hookup with 2K trimmer

I tried several times but without success to get the trimmer changing the output voltage of the LM317T . I tired to link the Pin 1 and 2 then all goes to ADJ pin of the LM317T and pin 3 to ground or ...
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1answer
533 views

current mirror circuit using BJT is alternative for LM317 current source?

I learnt about BJT and MOSFET current sources in my textbook,but they are used in IC chips.Is it possible to do our own current sources using BJT like two 2N2222 transistors in current mirror ...
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4answers
1k views

How to adjust LEDs brightness with photoresistor?

My goal is to reduce LEDs brightness dynamically with LDR. Power supply is 12V car battery. LEDs are about 3V. LDR will vary from 10k to 100k. I found out that I can use LM317 to adjust voltage. Now ...
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3answers
4k views

High Side Constant Current Source

I am trying to create a constant current source of 100mA to charge a single cell Li-ion battery. I see the LM317 thrown around a lot as a solution, but I'm looking for something that does not require ...