Questions tagged [lm317]

3-terminal adjustable linear regulator

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LM317-N output voltage lower than expected in LTspice Simulation

I am designing a circuit that requires a regulated 1.75 V source. After searching around I found the LM317-N voltage regulator and got it's SPICE model from TI to simulate it within my circuit. The ...
Jayson Okhman's user avatar
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2 answers
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I need more current than an LM1117/NCP1117 at 5V can provide (i.e > 1A)

I've got a simple power supply circuit to power-up some old-school TTL & seven-segment display boards (legacy computer front panel stuff). My first built for the 5V supply was with an NCP1117 (i.e....
Martin J Levy's user avatar
2 votes
2 answers
178 views

Overcurrent LED in LM338 circuit

I have an LM338 set up in current regulation mode, and I want to make an LED turn on when the current is maxed out (4A in this case) Where do I put this LED, and what other circuitry do I need? Is it ...
Klumpy7's user avatar
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TL431 With LM317 BMS

I am trying to make a BMS circuit that I saw online using a TL431, but as I am new to electronics I am having some problems when using the TL431. When I wanted to check the reference pin of the TL431,...
Fuad Frehat's user avatar
2 votes
2 answers
250 views

Create a 2mA charger for ML2032

I'm trying to create a simple LM317-based ML2023 charger. Unfortunately, I have very limited electronic skills. According to the ML2032 datasheet, the charging voltage of the ML2032 must not exceed 3....
Nemo XXX's user avatar
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LM317 does not regulate 12V to 8.2V

I am working on a project for which I needed to design a small linear regulator circuit in order to supply 8.2V for reading out sensors. I chose to use LM317, since it is quite simple to design and ...
karolista's user avatar
1 vote
1 answer
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Fixed-increment adjustment of constant-current source

I am using the LM317 as a constant-current source according to Figure 22 on the ON-Semi datasheet here. I would like to control the current in fixed increments rather than the continuous provided by ...
Klumpy7's user avatar
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3 answers
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Load regulation of constant current source

LM317HV data sheet provides following reference circuit for use as a "simple, fixed-current regulator" in section 9.2.9. It also specifies typical load regulation of 0.1%. I don't think the ...
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Calculating JFET stats for a constant current source [duplicate]

I need to find a constant current source for a variable LM317 current regulator (schematic below), and I would like to know which JFETs to use. Can somebody let me know how much current I need and ...
Klumpy7's user avatar
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Dynamo current limiting circuit with LM317

I'm trying to lower current to about 20 mA, but even attaching a resistor of 50 Ω, I'm still not getting the regulated 20 mA or so current with the LM317.
Ruqayya Saleh's user avatar
6 votes
3 answers
493 views

LM337 Unstable regulation

For an audio project, I need a low noise +/- 12V supply. I have a linear power supply of +/- 15V and I decided to use the LM317 and LM337 to decrease the voltage to 12V. The circuit that I use is the ...
Kostr's user avatar
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2 votes
3 answers
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LM338T Voltage regulator - I can't arrange the output voltage less than 13V DC

I have a circuit which purpose should regulate to voltage down to at least 3V. But when I try to adjust the 5kΩ potentiometer I only get minimum 14V voltage drop. I have a transformer which goes to ...
REW's user avatar
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1 answer
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L298N as LiPo charger

The L298N motor driver contains a voltage regulator (lm317), so is it possible to adjust the output voltage beyond 5V and 12V to charge a 7.4V lithium polymer battery?
oof baroomf's user avatar
0 votes
1 answer
128 views

Help with diagnosing a dual voltage power supply

Currently I’m working on my first electrical project and having a few issues with the negative side of the supply, it is not adjusting the same as my positive side, and I think the LM337 is blown? I’...
Infernoman's user avatar
5 votes
3 answers
875 views

LM317 voltage regulator varying voltage output depending on the load

I have designed a circuit using a LM317 to provide a 13 V voltage rail. The Vin is 24 V. I have voltage voltage divider networks which supply different voltages to a logic comparator which is ...
EmeraldMonk's user avatar
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2 answers
279 views

High-current transients with LM317 LD driver in Falstad

I have been building a laser diode driver in Falstad, but for the first 200 μs there is a current spike of over 70 A! This would mean instant death for my laser diode. If you are curious the laser ...
cats are the best's user avatar
4 votes
2 answers
1k views

How can I make this regulator output 2.8 V or 1.5 V?

I looked at an LM317AG-TN3-R which functions as a regulator. I'm trying to make sense of this part of the datasheet: I don't quite understand how I can now get 2.8 V and 1.5 V respectively. How do I ...
Cem Pamir Bana's user avatar
3 votes
3 answers
308 views

LM317's based "0-V to 30-V regulator circuit" - what is the purpose of diode on the schematic from TI's LM317 datasheet section 9.3.1?

What is the purpose of the diode in the schematic of the LM317-based "0-V to 30-V voltage regulator circuit" from section 9.3.1 of TI's LM317 documentation? Schematic: I simulated the above ...
pstr's user avatar
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2 votes
2 answers
348 views

Why is the LM386 so noisy when powered from wall?

I am using an LM386 to amplify an electret signal. Configuration for a gain of 200x is shown below. When powered from my bench power supply in quiet conditions, the output is around 4 mV (RMS). ...
broken.eggshell's user avatar
5 votes
3 answers
1k views

Does the LM317 voltage regulator have a minimum current output of 1.5 A?

The LM317 voltage regulator is supposed to have a minimum current output of 1.5 A. What does that mean? I am only familiar with the idea of a maximum current output. With this minimum current, will ...
SHEMIN A SALAM's user avatar
2 votes
3 answers
287 views

Increasing only current using LM317

For the LM317 there is a precision current regulator circuit. This circuit uses an LM317 and only one resistor between the out and adjust pins. The operation of this circuit completely satisfies me, ...
Deltinos's user avatar
1 vote
1 answer
297 views

LM317 adjustable current regulator for LED

I am driving a 10 W LED from a LM317 regulator. With a variable resistor in between the OUT and ADJ pins of the LM317, I can easily get an adjustable current source (20-350 mA). However, I need to ...
No Man's user avatar
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1 vote
1 answer
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Shorting LM317 in/outputs to skip over it and get full input voltage

I am new to the electronics world. I wanted to make a variable voltage source for various uses. I decided to use the LM317. I will be using a slide switch instead of the dip switch to select between ...
Ben Dover's user avatar
1 vote
1 answer
101 views

LM317 at low temperatures

The LM317 chip has an operating temperature range of 0 to 125 degrees Celsius. What happens if I use it at low (negative) temperatures? Will it work? What parameters will be affected by the ...
Stress's user avatar
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1 answer
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Is there a way to match multiple load impedances with one circuit

My goal is to create a test fixture that can provide multiple voltages such as +-24 volts DC to multiple devices with different input impedances for each device. The ranges of input impedances are ...
Brandon's user avatar
0 votes
1 answer
308 views

LM317 output overvoltage protection

I am new to electronic design and have two questions about my circuit. I know that an LM317 has stable output, but when I tested on a breadboard I found out that when I disconnected RV1, the LM317 ...
IMho's user avatar
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1 vote
1 answer
186 views

LM317 Voltage Regulator With Inversely Selected Output

I am dealing with an old circuit that used a curious form of voltage regulator control. It relied on seven resistors that it would control individually, and the parallel combination of this resistance ...
Smith's user avatar
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2 answers
214 views

LM317... Do we need resistors?

In the circuit below, I replaced LM1117 with LM317. Do I need to add resistors at the output terminal? and how can I calculate the output voltage in this case?
Haspacejar's user avatar
4 votes
4 answers
1k views

Why is this LM317 giving an unexpected output?

Just for fun, I used an LM317 IC with two resistors (1.5k and 470 ohm) to get an output voltage of around 1.8 volts and used this circuit with a wall clock. It worked amazingly well when I connected ...
Asmat Ali's user avatar
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2 votes
1 answer
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LM317 current limiting/set via differential amplifier works in simulator but glitchy when built

I am trying to build a single LM317 power supply, with current limiting using a differential opamp and potentiometers. I've came up with this (see schematic) and have built it on a breadboard but the ...
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3 votes
3 answers
307 views

Adding overload indicator to LM317

I am working at a LM317 power supply (tracking pre regulator) and I found on the internet a schematic for overload indicator, which I added into my simulation and into my test circuit. After ...
beard999's user avatar
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0 answers
69 views

LM317 vs Rheostat

I am trying to limit the voltage to a 12 volt , 25 watt silicone heating pad. I am trying to decide between a rheostat and an LM317 voltage regulator which I would control using an external ...
Oscar's user avatar
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1 answer
593 views

LM317 Vout instability under load

I hooked up a 9 V power supply to a LM317 (the power supply provides enough current, 2 A, and its heatsink is present) since I need to get 5.1 V in order to power a Raspberry Pi. 

The Raspberry boots ...
nhouse's user avatar
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-2 votes
1 answer
154 views

LM317t doesn't output as low as expected [closed]

I have an LM317t based variable power supply that I designed. According to the math on the regulator's datasheet my output range should be between 1.25v and 13.7v but after testing today my voltmeter ...
Andrew Graham's user avatar
-1 votes
1 answer
166 views

Is it safe to charge Lithium Ion battery directly with a 4.2 volt supply?

I have been working with Lithium ion 3.7 volts batteries and have been charging them using TP4056 module. However, the module doesn't last longer and gets damaged within a couple of weeks or a month. ...
Asmat Ali's user avatar
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1 vote
3 answers
1k views

Linear (LM317 based?) high current / voltage regulator ( 30 amps at 0 - ~35 volts)

I'm looking to make a linear (LM317 based?) high current / voltage regulator (30 amps at 0 - ~35 volts). I looked at some desings online but still have some problems with it. Maybe you can guide me ...
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0 votes
1 answer
373 views

Voltage drop with 2 LM317 in parallel/different output voltages

I believe it might be a silly question but I'm not 100% sure about this, so I would like your opinion: There are 2 LM317, both connected in parallel from the same source and they output respectively 5....
nhouse's user avatar
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0 votes
2 answers
500 views

LM317 is dissipating too much power

I used an LM317 in my circuit to get a regulated 1.5 volts output from a 3.7 volt battery using two resistors (220 and 60 ohm.) It worked fine, but the circuit dissipated too much power even when not ...
Asmat Ali's user avatar
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1 vote
0 answers
311 views

LM317 low output current

I need to make a 1.5 V voltage source for a motor with maximum current drain 1 A. I made this circuit: The output voltage without load is 1.46 V, which is fine. When I connect a load resistor which ...
Jakub Šmíd's user avatar
2 votes
1 answer
911 views

LM317 regulator with PNP pass transistor voltage drops when adding load

I'm trying to make a ~4V 2A regulator with the LM317. It works with minimal load but when I increase the load the voltage drops instantly to 3.4V. I'm not sure what's happening. I'm trying to build ...
Santiago Perotti's user avatar
0 votes
1 answer
443 views

Resistor and potentiometer values to obtain 1.25-12V variable with an LM317

I want to make a variable power supply up to 12V. For that I want to select resistor and adjust potentiometer values. I have calculated below values from this website.https://circuitdigest.com/...
usmandroid's user avatar
0 votes
0 answers
522 views

LM317 digitally-controlled constant current power supply

I'm designing and simulating (with the intention of building) a lab power supply. I like a challenge so I'm trying to make it digitally controlled (also because I'm a programmer). I'm doing this for ...
Clonkex's user avatar
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1 answer
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Design Questions for Dual Tracking Power Supply Using 15 Volt 800mA Secondary Transformer, LM317, LM337, and Op Amp

I am experimenting with the design for a dual tracking power supply using LM317/LM337. I recall circuit analysis but my design skills have not been used for a while so I have novice level questions. I ...
SystemTheory's user avatar
1 vote
2 answers
2k views

X9C103 10k digital potentiometer with LM317 0 - 20 V DC voltage source

I need some help about my current project. I am trying to do a voltage source which can be controlled remotely (0 - 20 V). I am using LM317T for this project. I examined the LM317T datasheet and ...
Ufkun Tarak's user avatar
3 votes
4 answers
1k views

LM317 potentiometer

I'm designing a voltage regulator using the LM317, and I've seen people using 2 different configurations when it comes to the potentiometer. I tested both on a simulator and on a breadboard, and both ...
Gabriel Santos's user avatar
1 vote
2 answers
160 views

Pre-regulator sizing

I want to make a voltage regulator for a symmetric power rail +30/-30V. The idea is to use an LM317 and an LM337. I want to be able to regulate with a Vin that can go up to +60V (and -60 and negative ...
Neeko's user avatar
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0 votes
2 answers
57 views

Does the lm317TG require a load resistor in the final design or just for testing?

I'm building variable voltage regulator, the regulator has levels of 9, 12, 15 and 18 volts and a potentiometer that allows for incremental adjustment between the levels, so at level 18v you can drop ...
DRC's user avatar
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1 answer
138 views

Does the LM317 take ANY voltage and convert it into the adjusted one?

I am pretty much a beginner in these parts, so can you help me? Does the LM317 take ANY voltage and convert it into the adjusted one? By "ANY" I mean that is in its voltage range, etc.
lowhatwo's user avatar
2 votes
1 answer
523 views

Can I use 2 LM317s cascaded?

I have a 20 - 0 - 20 transformer which is giving about +/-27 V after rectification. I need +20 VDC, +16 VDC, 5 VDC and -20 VDC. I thought of regulating from 27 to 20 then 20 to 16, and finally 16 to 5....
Gabriel Santos's user avatar
2 votes
2 answers
340 views

Is my heat sink calculation for the LM317 correct?

Using the formula PowerDissipated = (Vin - Vout) * Iout where: Vin = 12 V Vout = 2 V Iout = 450 mA Power dissipated = (12 - 2) x 0.45 = 4.5 W And heat sink value = (...
DRC's user avatar
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