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Questions tagged [lm317]

3-terminal adjustable linear regulator

19 questions with no upvoted or accepted answers
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2
votes
2answers
63 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 = (...
1
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0answers
44 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 ...
1
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1answer
77 views

Will this LM317 Circuit work for my application?

I am attempting to design a circuit to charge lithium 18650 batteries is a 3S configuration. I understand that a BMS is recommended, but I am not concerned with that. I have built this LM317 circuit (...
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0answers
686 views

Op Amp-based CV LM317 power supply

As many others before, I'm aiming to build my own simple CC CV lab bench PSU based on the LM317 regulator. Now, I've defined most of the circuitry, but I'm stuck with a particular design choice ...
1
vote
1answer
107 views

Dual channel linear power supply

As a learning project, I'm trying to create a simple linear power supply using LM317. The basic circuit is well documented on internet, but I want to create a variant that allows me to have multiple ...
1
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0answers
40 views

how to choose/design a capacitor value for surge current(for protection) for DC brush motor?

I am driving a DC BRUSH Motor at 30.V.D.C and the current is 300 Millie ampere, it is powered by L.M.317 I.C .My sir is suggesting to provide a capacitor as a protection form surge/peak current ...
1
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0answers
139 views

How does the LM317 bypass adjustment terminal reduce ripple amplification?

According to the LM317 datasheet it says that the adjustment terminal must be bypassed to ground to improve ripple rejection, so that the ripples aren't amplified. Could anyone explain how this is ...
0
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0answers
70 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 ...
0
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1answer
57 views

Driving strings of high power LEDs - different ways with fault protection

I'm trying to find the best method for driving around 30 x white LEDs plus 10 x RGB. The power supply can be 24V. The LEDs will be dimmable, 3W or 1W, 0.350A or 0.7A (I'd need to limit the current a ...
0
votes
1answer
69 views

Variable Current Lead Acide Battery Charger

Digitally controlling charge voltage with some regulator like Lm317 is a matter of using some resistor and transistor as stated in lm317 datasheet to select from multiple pre defined voltage. But what ...
0
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1answer
101 views

What is the voltage drop across a TIP41c when it passes 2.9A for long durations?

simulate this circuit – Schematic created using CircuitLab I'm having trouble understanding from the datasheets what exactly happens when I put a circuit as follows: The two 20W LED don't have a ...
0
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5answers
107 views

LM317 / linear regulator, estimate of heat capacity

Quick question - what do you think the heat capacity of a LM317 might be? The use case is that I want to ignite e-matches, which requires are short duration high current and would prefer to just use ...
0
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1answer
41 views

Ni-MH battery charging issue - custom built transformers, LM317 gets warm

I had one variable voltage power supply built and I have been using it frequently. Although I had no issue until charging Ni-MH and Ni-Cad batteries with this power supply. Lead acid battery, ...
0
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0answers
50 views

Higher input current than output current in LM317

I am doing a power supply to a TFT Display that works with 3.3V, my main supply is 12V and TFT current draw is approximately 150mA (A simple schematic of my circuit is below). I put two LM317 because ...
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0answers
167 views

LM317 using 2N2222 as current limit

I am trying to build a current limiting circuit using LM317. The goal is to limit output current to ~150mA with 25V input and output at >20V. I built the circuit according to ST datasheet, using the ...
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0answers
145 views

What do you think about my PSU design?

I have designed a symetrical PSU using LM317, LM337 plus power BJTs. The desired output range is at least 24V-2V @ 6A max. Altough not shown in the schematic, i plan to add power resistors and a ...
0
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0answers
316 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 ...
0
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0answers
123 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 ...
-4
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2answers
1k views

LM317 output voltage to 0 V with transformerless negative voltage created through a buck converter

I try to construct a shut down pin or a feature which can set the output of LM317 or LM78XX with negative voltage that is created through a transformerless buck converter. A buck converter having ...