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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1answer
61 views

1500-6000V linear regulator (noise eater)

Is there any known approaches to regulate HV in the range of 1500-6000V in order to eat noise? Low-side regulation is a possibility. The idea is to get ~100V higher voltage than needed, and then ...
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3answers
8k views

Odd PCB Layout for Voltage Regulator

I am reverse-engineering a board which has a Xilinx Spartan 3E FPGA, with VCCAUX powered by a 2.5 volt regulator. Below is the PCB layout for the regulator part of the circuit, and something seems ...
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0answers
42 views

Changing the target voltage of an lm7812 from 12V to 10V [duplicate]

The lm7812 won't start regulating until the input bypasses 12V. I want it to be regulating starting from 10V. so if the input is 11V, the output should be 10V. (behaves like an lm7812) I read that ...
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6answers
143 views

Is it possible to use 7805 regulator without capacitors at its input and output pins?

I have to drive a magnetic buzzer whose current is 50mA and max. voltage is 6V. I will use 7805 regulator to drive it as my supply voltage is variable 9V to 24V DC. There will be another small load ...
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3answers
107 views

Output capacitor in LDO regulator

I want to use an Analog Devices LDO regulator (ADP7104ARDZ-5v.) When I checked the datasheet, I found out that it requires just a 1uF capacitor on the output pin. Then I searched more and I found an ...
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2answers
60 views

24v dc High current variable speed Voltage regulator

I’m in need off a high current voltage regulator. I know a little about electronics, but not on an engineering level of designing stuff. I have a few stuff on scrap boards that I can use that lying ...
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1answer
42 views

Voltage regulator circuit

I am using this linear regulator and the application circuit looks like this: Is the above circuit good enough? I have a habit of putting a series ferrite bead on the input side but after reading a ...
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1answer
40 views

I am looking for a low power 2.5V linear regulator. Any ideas? [closed]

I'll try searching mouser and digikey but i was wondering if there was a frequently used 2.5 regulator with low quiescent current (preferably lower than 5mA). Input must be: Vin<10. I am in a bit ...
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0answers
50 views

Choosing power supply for device [duplicate]

This question is not Duplicate I am building a device which has a Raspberry Pi 3b +, custom Atmega328-PU or AU circuit (homemade Arduino), ws2812 SMD LED Arrays. Here, Raspberry Pi will provide ...
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54 views

210v DC CV/CC supply

I have an old variable power supply that consists of a multi tapped transformer, a bridge rectifier and a choke. The transformer has two sets of taps on it, 6 coarse and 6 fine, giving 36 voltage ...
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2answers
69 views

Limiting current to a LiPo battery [closed]

(Updated: Amended text. The smaller battery is a lower voltage than I originally thought.) I have a small 7.5V LiPo battery that needs a top-up charge of max (say) 500mA from a large 12V LiPo battery....
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2answers
1k views

Can't get 5V 3A DC constant

Here's the circuit I am trying to build. I want to get 5V 3A DC output but it's giving above 7V and 4A. I have checked it in the multimeter attached in the diagram. Can any one explain what's ...
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0answers
102 views

3.3V LDO Selection

If you've ever tried to find an appropriate LDO for your project you may have noticed the incredibly vast range available on the market. During my searches, I discovered this particular regulator ...
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2answers
3k views

What is the role of the transistor and diode in a soft start circuit?

Please can someone explain the purpose of both the transistor and diode in this soft start circuit
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2answers
822 views

LM317 - Calculate dissipation due to voltage drop

If I use a linear voltage regulator as LM317: Input voltage = 24 V Output voltage = 5 V (so a voltage drop of 19 V) Mean load = 480 mA (peak load = 700 mA) From the datasheet, I read that maximum ...
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4answers
203 views

Aluminum electrolytic or ceramic capacitors for linear regulator input and output?

I am using this linear voltage regulator. The datasheet indicates the input and output values for the capacitance to use, 1uF and 10uF respectively. Should these capacitors be or a particular type, ...
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1answer
28 views

wiring ac input to linear DC power supply

I have a vintage linear DC power supply. Terminals 1 and 2 are labeled just "AC input". Wanted to double check if there is a convention for which pin is hot, or if the polarity is irrelevant in this ...
7
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1answer
811 views

Series pass transistor, LM7812

I am making a 12 volt regulator for a solar panel to power an audio amplifier. I already have a switching regulator for most application but it is very noisy for amplifier even with a lot of filtering....
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0answers
82 views

Powering and regulating supply DC voltage for a digital MEMS microphone

I want to use Infineon IM69D120 microphones [1][2] in an array (about eight of them), and I am confused as to how exactly (with which components) should the MEMS microphones be supplied. I chose USB ...
14
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3answers
1k views

Will linear voltage regulator step up current?

I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or ...
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2answers
105 views

How can I estimate TL431 output voltage swings based on datasheet alone?

I am trying to design a series-pass regulator that brings 12V down to 3.3V. If I see a 20 mA step change in current, I would like to stay within a certain output voltage range (±2%). What parameters ...
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2answers
108 views

Voltage regulator and loss of ground

I have a design that has a +24VDC supply, a 7805 voltage regulator converting it to 5 volts and then a microcontroller and some peripherals behind the regulator. The design and the 24V supply ...
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0answers
37 views

Thermal Faliure of thermal overload protected ICs

I have encountered a number of instances now where ICs that supposedly include "thermal overload protection" will still heat up until they fry. Examples: LM338,LM2576. These devices datasheets ...
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0answers
64 views

Linear Regulator Operation

I have a linear regulator with three pins. It's identifier is LM7805. I've taken a look at it's datasheet and it looks unlike linear regulators I've encountered. Is the the op amp circuit included in ...
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2answers
84 views

AMS vs LD vs ZLDO vs NCP in 1117 Linear Regulators

I was in the process of choosing a 3.3V Linear Regulator for my ESP based Project when I stumbled upon the different types of these voltage regulators. The 1117 regulator had different prefixes, AMS, ...
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4answers
253 views

Too low efficiency with “0-30V 2mA-3A DC Regulated Power Supply unit with Continuously Adjustable Current Limiting Protection” PSU kit [closed]

I ordered and assembled the kit (link and image added below). Everything works fine. But as everybody knows, it requires a great heat sink for the regulator. The ordered unit costs less than $5, but ...
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2answers
63 views

Is this a suitable Voltage Regulator to replace an old circuit on my board and is my logic correct?

I have 4 of these 2n3904 transistor setups on my board: A1 -- requires 5v on these 2 connected pins to be enabled. I control this by driving r2 high at 3.3v which should allow 5v to flow through the ...
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1answer
55 views

PI controlled linear voltage regulator with overcurrent protection

I designed a simple linear voltage regulator for high voltage application around 500V which is controlled by a PI controller. Schematic 1 shows the raw design using a bipolar transistor to control ...
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1answer
63 views

Can I use same LDO for two outputs?

Can I use same LDO for two or three outputs? Given that the LDO provides enough needed current for three devices.
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1answer
142 views

How to connect two LDOs in parallel?

I have two LDOs that convert different input voltages into the same voltage. I'm not sure how to safely connect the outputs together so they become the same signal and can be both be used to power the ...
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1answer
153 views

LDO, linear regulator or DCDC buck converter

I would like to power an ESP32 in my car, so the input voltage is between 11 and 15v, and the output voltage should be 3.3v to power the Arduino board. I thought that LDO were only for low dropout ...
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2answers
435 views

LM317 Soft-start circuit

assuming the below circuit is functional. Can you tell me how soft-start part is working? Would the same setup be valid for Vin=~3V and Vo =~1.3V, or would I need to change the C1 and R3. Also how can ...
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2answers
95 views

Any downside to feeding a buck regulator into a linear one?

I need to convert 12 V down to 5 V and 3.3 V. I am using linear regulators right now but they get pretty warm and eventually I would like to supply more current for it (around 500-700&...
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1answer
38 views

LM2940, 7808 and Multichannel PWM chip

I'm putting together a circuit board to power and dim 5 LED channels. The average voltages on the channels are 12.3V, 11V, 11.4V, 7.8V, 6.6V, and max current is 1A. So my current plan is: 12V ...
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1answer
429 views

High voltage linear regulator (with pre-regulator)

I need to build a linear voltage regulator like this: The problem with the usual linear regulators (LM317, LM337, ..) is the limited voltages they can withstand. I have taken inspiration from a ...
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1answer
146 views

PWM duty cycle RPM regulation via sensing DC motor current

I have a DC motor that needs to be RPM regulated, that is, it needs to turn at constant RPM regardless of the load. I've read this can be done by monitoring current thru the motor windings and ...
0
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1answer
175 views

Bad 100Hz ripple in linear regulator circuit

Background I'm a beginner trying to make a linear regulator and made some decent progress on a breadboard powering from a 20V laptop charger. After battling off the typical opamp instability issues I ...
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2answers
574 views

What is a simple voltage limiting circuit?

I am searching for a neat solution for an input voltage limiting circuit. Situation: I have a circuit with an input voltage range from 6 V to 20 V at 3 A peak (the load), however my source can be ...
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2answers
72 views

Use regulator when input voltage is above threshold other wise use direct input voltage

I don't have much practical knowledge of electronics. I am trying to operate esp12e with single Li-ion battery with charging circuit. I am planning to use a good LDO regulator because Li-ion battery ...
0
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2answers
277 views

Best power supply for a BLDC motor; linear or SMPS?

I am coming into a design that uses a custom designed, 24V brush-less DC motor controller. I am wondering, is it better to power this type of system with a linear power supply, a switch mode power ...
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3answers
120 views

Will battery last longer with larger capacity but lower efficiency (high V through LDO) or vice versa?

Given a simple circuit of a draw around 28mA (when supplied 3.3v). I'm trying to maximize run time on a battery, but working with what I've got on hand... I have the following batteries: 5000mAh 3S ...
2
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1answer
62 views

Using a higher C than necessary in a voltage regulator circuit

I've two questions: If I've a voltage regulator that says in the datasheet to use electrolytic capacitors is it possible to use 'normal' capacitors with the same capacitance? I've the circuit drawn ...
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3answers
375 views

Negative input, negative output switching regulator?

I've got a component within a larger device that requires both +15 and -15V, drawing about 100mA per rail. In addition, the main power supply of the larger device is providing +/- 28V, with a common ...
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6answers
3k views

Best way to power a microcontroller, SMPS vs Linear Regulator

I'm using a 12V adapter and a 2S 7.4V Li-ion battery to power my electronics, and I would also like to power my MCU with it. To switch between the adapter and battery I'm using a BQ24133 from TI. I ...
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1answer
59 views

Any 12 or 14 v 100amp voltage regulator it? [closed]

I have searched the Internet but didn't find one, can anybody please suggest me any regulator ic that is 12 or 14 volts and can bear upto 100 amps.
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1answer
359 views

Explain adjustable 4A regulator

I cannot understand how this circuit works. https://imgur.com/a/OAQSF4Y I have found a basic explanation online but is not enought to make calculations. "Using three LM317-N devices in parallel ...
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0answers
63 views

MCU controlled adjusting LED current with current sensing regulators?

I'm really sorry for the noobly formulated question, if I knew how to formulate it I'd probably find what I need by searching, this has to have been asked and dealt with many times. I've been using ...
2
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1answer
146 views

Linear current driver with several BJTs in parallel

With the circuit setup shown below, if I have available a type of Q2 transistor with a certain maximum dissipated power and need that D1 withstands a large current that would lead Q2 in trouble, it is ...
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3answers
229 views

Lm317 input connected to output?

I am figuring out the schematic of an existing e-bike controller. Specifically I am trying to replace an lm317t with a custom made switch regulator that outputs the same voltage. But first I want to ...
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0answers
56 views

Stable 12V 1.5A

I'm in need of a stable 12V 1.5A power which I could carry with myself. One way of doing it would be to strap, say, 12x 1.2V rechargeable batteries and use LM317. But then I read about buck ...