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Questions tagged [linear-regulator]

A linear voltage or current regulator provides a continuous non-pulsed supply of current or voltage. It may be fixed or adjustable, and can be put under control by a CPU/MPU. In spite of sometimes low efficiency they are popular because they provide clean noise-free DC current or voltage, as opposed to switching supplies that can be very efficient with power regulation but induce much RF noise into the outputs which need extra parts to filter out.

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Voltage unexpected noise

I'm quite new to the electronic designs so might have made some horrible mistakes in the below circuit. It works as expected but it has a problem. The voltage at the output has some sort of noise ...
Marcin Pluta's user avatar
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2 answers
36 views

Dealing with High Voltage Low Current Transformer Inrush and bypassing a Thermistor

As a learning project, I am designing a power supply section of a guitar amplifier that uses a 120V Primary, 250V 45mA 40VA Secondary Transformer. Without any thermistor in-line on the main supply, I'...
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Linear regulator doesn't always operate correctly depending on order in which power pins are connected

I have a pair of +10.5V and -10.5V linear regulators (XC6216DA52PR-G and XC6902NA51PR-G respectively, both in the SOT-89 package) wired up as shown in the first schematic. The input power is from a ...
Jordan Melo's user avatar
5 votes
4 answers
3k views

Can somebody explain to me how this circuit actually works? (Linear voltage regulator and PNP transistor as current boost)

This is from the datasheet of LM2931. What baffles me is how this actually works. The LM2931 drops the voltage to 5 V and I assume the 68ohm resistor is there to drop the voltage around 0.7 V to open ...
Joonas Joensuu's user avatar
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2 answers
75 views

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
0 votes
2 answers
28 views

SGM2052 LDO Vbias pin connection

I am using SGM2052 LDO in my design. Using its fixed voltage version.In the datasheet you can see that it has a pin called Vbias. The description of Vbias is given below. Below is the typical ...
Confused's user avatar
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LTspice, Variable Resistor

I am new to LTspice and creating circuits in the application. I want to make a variable resistor to test and observe a current limiter circuit in a DC power supply. For example, it starts at 10 ohms ...
Dereck's user avatar
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2 answers
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Ferrite bead on a SMPS output [closed]

Suppose I have an instrument which needs a very clean power supply line. I have an SMPS which outputs 24 V at 3.2 A, which is then cleaned via a LM1084 linear regulator. Given that the output of a ...
lemon's user avatar
  • 590
4 votes
1 answer
306 views

Hall-effect sensor PWM jitter from switching converter

I am designing a circuit to power two magnetic sensors using a Li-po battery (nominal voltage = 3.7 V), DC-DC boost converter, and then either an LDO linear regulator or a buck converter to generate a ...
rtx_q505's user avatar
1 vote
2 answers
142 views

Linear regulator burns, probably due to charging current of output capacitor

I have the following voltage regulator circuit (AMS1117 SOT-223): simulate this circuit – Schematic created using CircuitLab C1 is ceramic and C2 is tantalum. The 3.3V output is used to power a ...
Jiří Maier's user avatar
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Alternate voltage regulation for a linear power supply

I'm building a linear power supply. The first stages are all working great. Coming out of the rectifier and filter caps, I have 28V DC. I also have a voltage reference circuit (LM317) that gives me a ...
byl's user avatar
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3 votes
1 answer
161 views

Less than minimum charge voltage for NiMH battery and extra parts in a "simple" circuit

I was given the job of duplicating a "simple" box that monitors air flow in a duct. It seemed simple. I dabble in electronics (I design and build industrial control panels, starts, PLCs, HMI,...
xtal_01's user avatar
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1 vote
0 answers
103 views

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
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0 answers
39 views

Proper DC supply vs batteries

For the current limiter circuit(using voltage regulator), proper DC supply matches the simulation results. However, when a battery of equal supply voltage is connected, the circuit goes haywire i.e. ...
Soham Ghaisas's user avatar
1 vote
1 answer
50 views

MCU Breakout Power Considerations

I am designing a custom breakout board for my ESP32 Devkit-C used as a CNC controller. The ESP is powered from a Mean Well 5 V PSU (with a Schottky diode and some capacitance to ground). In this ...
ligvi's user avatar
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3 answers
116 views

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 ...
beardeadclown's user avatar
7 votes
2 answers
666 views

Understanding this linear series-pass regulator circuit

Please refer to the schematic extract above which is the positive half of a bipolar voltage regulator in an amplifier. It is a mostly classic design but there is a part I don't understand. The part I'...
Joe's user avatar
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3 answers
102 views

Reducing linear regulator heat via series resistor

I'm working on a project that uses four L293D motor drivers to control three stepper motors and one DC motor. Separately, there is also a small servo motor. The L293Ds receive a 6V motor supply ...
E.HP.S's user avatar
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1 vote
1 answer
126 views

How to avoid transient voltage spikes when powering up a device?

I'm using the linear regulator LP2985-50 from TI to power a set of op amps (NE5532). The op amps provide an analog signal to a component that is very sensitive to overvoltages. Upon power up, I first ...
oscar garcia's user avatar
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0 answers
26 views

I want to replace PID by linear quadratic regulator to control the speed of induction motor fed by Voltage Source Inverter under V/f scalar control

Can I just use the simplified scheme of constant v/f speed control (the open loop system) to design the linear quadratic regulator? I intend to use the Matlab command ...
RABE10 's user avatar
3 votes
3 answers
1k views

Using Linear Voltage regulators in parallel for a high current load

I need to build a high current 12 to 5 volt regulator. This will power neopixels, which draw 60mA each, and we have like 800 of them, so around 48A when all of them are on at full brightness and white....
Juan010's user avatar
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1 answer
67 views

Should I consider using two Switching regulators or one switching regulator and a linear regulator

I have a circuit that has an input of 24VDC. The circuit has two different voltage rails requirements. 12VDC @ 0.1A and 8VDC @ 1A. I have decided to use a swithching regulator from 24VDC to 8VDC, and ...
EmeraldMonk's user avatar
5 votes
7 answers
788 views

LDO stability with resistor in the feedback path

I am working on a circuit for measuring very low and very "fast" currents (think: measuring power consumption of an MCU). I found out that I can measure what I want with a sense amp and a ...
filo's user avatar
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2 votes
3 answers
250 views

Why is my 5V linear regulator giving out 6.34V?

Update :-(: I tested the pinouts of the IC with a multi meter and the connections are fine. Then I discovered I had done a very stupid mistake and connected Vout where Vin should have been connected. ...
John Snow's user avatar
  • 195
3 votes
1 answer
148 views

How to make fast CV/CC transition in linear NMOS regulator?

I want to design a linear regulator based on NMOS with CC/CV capability. I made a circuit with two separate loops (CC and CV), each of which is stable. The problem is in the transition moment when the ...
Vasiliy's user avatar
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1 vote
4 answers
134 views

Vintage LM317T Linear PSU Improvement Suggestions

Recently I came into possession of two very old linear PSU devices from 1993. I replaced the caps and tested the devices and both work. I have been using them in conjunction with 12 7Ah lead acid ...
Jonas's user avatar
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6 votes
3 answers
559 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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3 votes
2 answers
1k views

Should I be skeptical of a component when its datasheet specifies a specific type of capacitor?

I'm researching 5V regulators for a project and came across one that looks promising, but I noticed that its datasheet specifically calls for a tantalum capacitor on its output. Normally I wouldn't ...
E.HP.S's user avatar
  • 349
0 votes
1 answer
122 views

Overshoot on dc/dc converter

Any idea on what would the level of overshoot that this LDO can provide? Would that data/information on overshoot would be provided in the datasheet? If not, how should I understand that? I am using ...
Freshman's user avatar
4 votes
2 answers
503 views

Connecting linear regulators in parallel

I have seen some images in which two linear regulators of the same type (basically the same part number) have their outputs tied together. I believe this is being done to increase the total current ...
quantum231's user avatar
1 vote
2 answers
199 views

Preventing Op Amp oscillation in PNP Linear Regulator Supply

I am currently designing a PNP-based linear regulator (see images). However, I am having trouble with it oscillating. There is a sizable 200 mV saw wave oscillation at its output. No, it's not power ...
Kuba0040's user avatar
0 votes
0 answers
39 views

Grounding Circuit with two Power Supplies Wired Together

I am trying to operate an x-ray tube that requires a high-voltage supply and a lower-voltage filament supply. The high voltage supply consists of a Cockcroft–Walton voltage multiplier, and the ...
import_hill's user avatar
1 vote
1 answer
46 views

Determining feedback resistors for the BD00FC0WFP LDO voltage regulator

I'm trying to configure the regulator to output 4.5V. From what I gather, the output voltage is governed by the voltage divider between Vo and GND where the device's FB pin reads the voltage dropped ...
debounce's user avatar
1 vote
1 answer
430 views

What is the highest practical bandwidth of a linear voltage regulator/LDO?

I am trying to evaluate what the highest pratical bandwidth of linear regulator/LDO is. To be more precise, I am looking the bandwidth of the transfer function Vout/Vin. I think the bandwidth is set ...
Jess's user avatar
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0 votes
0 answers
896 views

Shelly Uni IDC with a potentiometer as a garage door open sensor (percentage) - voltage regulator with low current

first of all, I'd like to mention that I'm not an electronic engineer (done some ESP8266 and Raspberry solutions, but mostly by using ready-made components and shields), so if some info is missing or ...
Misiu's user avatar
  • 101
2 votes
0 answers
77 views

LP2951 external transistor

I want to use LP2951 reference design from ONsemi datasheet (picture below). I'm not going to build the current limiting section of the schematic because the device will have external overvoltage/...
Tolik4's user avatar
  • 151
3 votes
1 answer
126 views

High voltage MOSFET linear regulator failure

I designed the circuit below for an FSAE electric vehicle, for which the rules require an HV-powered LED to be lit when the HV bus is above 60 V. In simulation, the circuit works very well. In real ...
AgentRev's user avatar
  • 225
0 votes
5 answers
108 views

Linear regulators in series [closed]

I'm helping a friend review a schematic. It's a battery-powered project with three rails: battery (AAA 3 x 1. 5 V) and two linear regulated rails (LP5907MFX-1.8 and LP5907MFX-3.3). The 3.3V reg is ...
okwestern's user avatar
1 vote
1 answer
67 views

LM317 current regulation below 20mA

I made small regulator which is supposed to deliver from 20 mA to the exact lower limit of LM317 for current regulation in self-biased mode. The question is, the LM317 datasheet says it's rated 10 mA ...
ogeid's user avatar
  • 205
0 votes
2 answers
142 views

What happens when a resistor fails?

simulate this circuit – Schematic created using CircuitLab I am trying to test my LT 3083 voltage regulator using a chip resistor to model the load. My input power was 5V and I was trying to ...
nmr's user avatar
  • 133
0 votes
1 answer
318 views

Power Good Connection for Regulator Sequencing

For powering Artix 7 FPGA I need power sequencing. In the Artix-7 data sheet it states that the recommended power-on sequence is VCCINT (1.0 V), VCCBRAM (1.0 V), VCCAUX (1.8 V), and VCCO (3.3 V). ...
Cenk's user avatar
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1 vote
0 answers
89 views

Unknown "JE07" SMD SOT-89-3 Regulator

Can someone please help in identifying what this "JE07" SMD is? All I know is that 28V goes to the tab of the sot-89-3 smd part which is also the middle pin. I assume that is the input pin. ...
gcshum's user avatar
  • 11
2 votes
1 answer
93 views

What is the simplest way to adjust the input voltage for a linear regulator?

I have a garage door opener for which I need to replace the radio receiver. The opener outputs a DC supply voltage for a receiver at 34 VDC. The receiver has an input range specification of 12-24 V AC/...
tg85's user avatar
  • 63
4 votes
2 answers
350 views

Linear regulator thermal information missing in datasheet

I'm considering to use UA78M33CKVURG3 in my design, so as with any linear regulator I have to make sure it will be able to handle the current draw in the worst case scenario. To calculate what the ...
StefanoN's user avatar
  • 480
6 votes
1 answer
358 views

Why is this regulator circuit unstable?

I'm trying to use a LDO with higher current (5 A in my case) than what it's rated for. I derived for this the following circuit V is a noisy voltage source between 16 and 22 V (mainly 50 Hz 1 Vpp ...
Jonas Daverio's user avatar
1 vote
1 answer
68 views

Optimising standby current of battery operated designs with momentary power activation - circuit example from digital level

My digital level flattened its 9 V battery within 2 weeks of little use, so I measured its standby current which came out at nearly 2 mA! I took the cover off was shocked to see the battery connected ...
Warrick's user avatar
  • 127
0 votes
2 answers
81 views

Parallel split rail supply with only positive regulators

I'm designing a +/-12V split rail supply for a eurorack (modular) sythesizer. I was adviced to put a pre-regulator block at a higher voltage a connecting to it several point-of-load regulators. ...
Jonas Daverio's user avatar
0 votes
1 answer
516 views

LQR Infinite Horizon vs. Finite Horizon vs. Receding Horizon?

I don't know if this is the right forum, but I would like to know in words the difference between these 3 forms. I have searched online and in books but there are often demonstrations packed with ...
KaleM's user avatar
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1 vote
2 answers
675 views

How can I power an ESP32 with a 54V battery using a buck converter?

I need to power an ESP32 board from a 54 V battery. For that purpose, I understand that I need to step it down to 5 V so I need to design a step-down buck converter. I tried the following circuit ...
Nikhil Pandya's user avatar
1 vote
1 answer
107 views

Selecting the current rating of a LDO linear voltage regulator

I'm prototyping with a development board which has a 3.3 V rail and I have an IC that needs to be partially powered at 1.9 V. From my research, LDO linear voltage regulators are ideal for this ...
Daniel's user avatar
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