Questions tagged [voltage-regulator]

A voltage regulator is an analog circuit that produces a stable output voltage that doesn't vary with input voltage or load changes. Switching regulators are much more efficient than linear ones.

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DC Voltage Regulation - 5vdc output, 12, 24, 48vdc input [on hold]

I am designing a pcb that gets used in 3 different products with 3 different voltage supplies. One uses 12VDC power brick, another 24VDC, another 48VDC. I am working on the new design for this pcb. In ...
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Polarities of high current bypass, and short circuit protection, transistors on LM7912 - NPN or PNP?

With reference to Olin's answer to Connecting Voltage Regulators 7812 in Parallel for High Current, and likewise the examples from the Fairchild, TI and ST datasheets, a PNP transistor is used (i.e. ...
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36 views

Slight drop in voltage regulator circuit

Below is a voltage regulator circuit for which I measured Vo and Io over a range of load resistance values. Why is there a slight drop in Vo when Io is increased, does it have something to do with the ...
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37 views

Computer controlled potential difference across wires

I am trying to design a circuit to control the potential difference across 2 stainless steel wires. The two wires are connected together at one end (common node) and on the other end, one wire is ...
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18 views

connect 5v fan from voltage regulator

i have a 12v power supply and fan 5v 150mA and voltage regulator L7805 cv to reduce the voltage to 5volt . i need a circuit to just turn the fan on /off by switch . can i connect the fan directly to ...
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46 views

SMPS feedback circuit with voltage regulation and current limiting

i’m self learning electronics for a few months now and i choose my first project to be a bench SMPS. Since it is my first circuit design ever i really need some clarification. My SMPS is 2-switch ...
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58 views

LF33CV voltage regulator overheating

I'm trying to turn on a laser (3.3v - 4.5v, 100mw) using a 9v battery and LF33CV as voltage regulator(TO220 package, 3.3v output). After 20 seconds the voltage regulator is getting so much hot. I was ...
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Solar charger diy - question about voltage

Goodmorning everyone. I've recently made a usb solar charger, connecting a 10W 12V solar panel to a voltage regulator and then to a female usb cable. (The panel already has a blocking diode built in, ...
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Multiple LEDs, Multiple Switches, One Power Supply

I am working to design a circuit like the following where the power supply is 9V, and there are multiple LEDs to be potentially lit, and all are turned on or off either by a switch or by air pressure (...
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99 views

Power a 12V 30A (instantaneous) load. Possible with 18650 cells?

(novice) Hi, I'm driving a 12V load for ~1s second very infrequently, at a draw of about 30A. The load isn't particularly voltage-sensitive. Total mAh isn't that important. I have a supply of ...
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44 views

Split rail DC/DC converter

The input voltage of my system is ±15V. I need to generate the ±5V voltage. As I need it to power precise analog components (ADC, op amps), my plan is to use DC/DC converter for reducing it to, lets ...
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voltage regulator current draw

I have a question about the operation of a voltage regulator. The supply is 12V and can provide 15W (max current draw 1.25A). Now when I use a linear voltage regulator down to 5V do the 15W still ...
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41 views

Regulators lm75xx in series : 12v to 5v [duplicate]

What do you think about puting regulators lm75xx in series in order to get less heat loss as possible : 9v-- to 5v-- to 3.3v , to get 3.3v from 12v supply? The idea is to not using a switching ...
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5 V home network

I'm planning on adding multiple IoT devices in my house, and I'm looking for an elegant solution to power them all. They'll all need 5 V, a small number of them (cameras) would draw up to 2 ...
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91 views

3.3 Volts Output on 1.8 Volt Regultor

On my circuit board, I have three different voltage regulators. I have a 5V Buck converter that goes into a 3.3V LDO and then finally 1.8V LDO. When I power the board with a USB and do not use ...
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How To Run Shaving Machine Without Bettary? [duplicate]

I'm just an amateur in this and I Need Help.. I've drawn this circuit of my Shaving machine and I want to remove the battery and connect it directly to one of these phone chargers-: The first: ...
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177 views

Arduino Pro Micro Frying Up

I made a PCB with two Arduino Pro Micro 5V on it as a control system for a machine. The PCB is powered by a 24VDC PSU and a part of that 24 VDC goes to a R-78C12-1.0 DC-DC converter. That gives 12VDC ...
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56 views

Reducing 16.5VDC battery output to the range of 13.8VDC +- 15% without introducing noise for 15 Amp load

The title pretty much says it all. The (up to) 15A load is a ham radio, which is the reason for the 'no noise' constraint. Maybe a tiny bit of noise is OK? I don't know how I could tell. To save you ...
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39 views

Excitation current calculation for alternator

I have an old brush alternator where field excitation happens in the stator. Unfortunately no information is given about the required field excitation current. The alternator is rated 3 Phase, 400V, ...
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95 views

12V voltage regulator

simulate this circuit – Schematic created using CircuitLab I have bought the LM78H12K 12V voltage regulator, for the 12V output. My input voltage is 17 V DC, but unfortunately this component is ...
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1answer
58 views

Do I need a protection diode to prevent reverse current flow into a voltage regulator?

I have a 78L series voltage regulator that is used when a power supply is connected. When the power supply is absent, battery power is used. The battery will skip over the voltage regulator. The ...
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278 views

Most efficient way to convert from 3.5-4.2V (singe cell LiPo) to stable 3.3V for currents up to 500 mA?

This question is hypothetical - there is no specific project, I just have an obsession with efficiency. I use a lot of 3.3V modules, and have a bunch of single-cell LiPo batteries (which are amazing)...
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1answer
45 views

Problem Powering 13.3 inch LCD Screen with 3.7v Battery [closed]

I have been working on a project that involves running a 13.3 inch lcd screen off of a rechargeable battery. I bought the lcd screen and controller board listed below and verified that it was working ...
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2answers
177 views

Feeding microcontroller and linear actuators (motors) with the same power supply

I have already made a diagram using a motor controller. The details of the actuators are: Input voltage: 12VDC Max Load: 750N(168.607lbs) Stroke Length: 16 inch Travel Speed: 12mm/s Duty Cyle: 25%. ...
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99 views

Is running two voltage regulators in parallel safe?

Components Battery (7.5V 6A Max) D24V25F5 (5V 2.5A step down) U3V50F12 (12V 5A step up) Raspberry Pi 3 (5V 2.1A-2.5A) Motor (12V 3A stall) (Using H-Bridge) Would the setup be suitable? I much ...
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718 views

How to control the output voltage of a solid state relay

Considering this solid state relay: The output voltage can be from 24 to 380V. How can I control this voltage? Is it proportional to the input voltage? What I need is a voltage regulator that can be ...
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EP53F8QI Short to GND fault

We have a design with an EP53F8QI that multiple ICs have been burned both at room temperature and +80 °.C. We are using it to create a +3.3V and on fault we have found that the +3.3V supply is shorted ...
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52 views

Adjustable LDO feedback resistor values

I'm designing a circuit using an LDO voltage regulator; specifically the LD39130SPUR from ST. This variant of the part allows for an adjustable output voltage via a potential divider as seen on page 8 ...
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44 views

MP1584 5v regulator voltage drop problem

I was debugging the MP1584 module, 5v regulator circuit in the PCB. I have attached my debug circuit below. I have completed my circuit in breadboard and PCB also, but I was connected to any load ...
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42 views

How to prevent voltage at output of TPS54302 to feed input?

I have designed the circuit below with the TPS54302. What happens is that if someone accidentally applies voltage to the output (Let's say 12V) the input receives the same 12V and provides voltage to ...
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1answer
36 views

Voltage of capacitors for MIC29302

I want to use MIC29302 as regulator in SIM800L circuit. In the suggested circuit in the datasheet there is a 100 µF capacitor before the regulator and a 330 µF capacitor after the regulator, but ...
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1answer
39 views

Voltage Threshold Gate Circuit from 0-5V Input

Background: I have a circuit in which when Vin is applied, the super capacitors have to be charged before anything else in the circuit can be utilized (otherwise I will undervolt the devices I am ...
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98 views

How to properly step down the voltage of a DC+AC signal that then goes inside a pin of a PIC?

The reason of the question is because i don't know if this is the correct way of regulating a signal that goes inside the pin of a PIC that accepts a signal that goes till 3V3. In the following image ...
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241 views

Some questions about a series pass transistor & op amp voltage regulator [closed]

I have the following voltage regulator using a series pass transistor and an op amp providing the base voltage: I have three questions: How do you calculate the output voltage for such a regulator? ...
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1answer
123 views

LDO Heating Issue

I am working on a PCB project and having a problem with the linear regulator IC. I want to be able to maintain a relatively constant temperature for the heating element. The whole system is ...
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2answers
129 views

PNP linear regulator problem

I am designing a linear step-down regulator using a PNP pass transistor. The output of the regulator is good at no load. When I connect my regulator to a battery supply, leave it for 2 seconds and ...
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2answers
86 views

LM317 to step voltage up

I am sorry for questioning the "law of conservation of energy" first of all. The expression for the output voltage of the LM317: Vout=1.25*(1+R2/R1) contains no any relation to the input voltage. ...
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91 views

DC voltage after rectifier

Is my calculation correct? I want to tranform 240Vac output of 5Vdc after voltage regulator. The transformer I am interested in is VB 2,0/1/6: https://docs-emea.rs-online.com/webdocs/0f46/...
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3answers
249 views

LM1117 3.3 output gives 4.2

I used this circuit and formula as a reference for 5V to 3.3V It's from the LM1117 datasheet but output gives 4.2V. Here is my circuit: I changed resistors with different values but output give ...
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47 views

Mosfet Regulator heating issue

Guys i trying to step down voltage using mosfet. Application: Input battery supply 40 to 50 volt Output voltage is 12 volt not more than 500 ma. Mosfet heating issue due to... Since the mosfet is ...
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2answers
50 views

Transistor series regulator heating

Hi friends i am trying step down converter using transistor. Application: Micro controller power-supply = 3.3 volt Input battery supply range = 10 - 13 volt So i use BD139 for stepping down ...
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3answers
93 views

How to accommodate a range of input voltages

How does a designer generally accommodate for a range of input voltages in their circuit? For example, my design needs to be able to accept 12-24V where it uses 12V and 9V at seperate areas as shown ...
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3answers
43 views

How does increasing the duration of the transient response become a problem?

I'm looking at the TI TPS727 LDO regulator datasheet and it says this: 8.2.1.2 Transient Response As with any regulator, increasing the size of the output capacitor reduces over- and ...
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33 views

simple clamp circuit resistor calculation

Hello guys i want to calculate the resistor R in this circuit.Can anybody help me? The value of zener diode(VZ)=4.8 volt. well i try to simplify it My question is is my solution is right??If not ...
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79 views

Why is the LT3080 input voltage limited to 36V?

The LT3080 is a current source based generator, that is, the reference voltage is set by the fixed 10uA flowing through the adjust pin and its external resistor. If so, I don't see (according to their ...
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81 views

Need a processor to be able to turn off its own power

I have a processor that is powered by a mains 5V power from a wall adapter, and has a short term battery backup. I need the processor to turn on automatically and immediately when 5V mains supply is ...
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3answers
42 views

How to reduce voltage from shift register to ESP32 MISO pin?

In this circuit I have sensors that are rated for a minimum of 6V connected to a 74HC165 which passes its output to the MISO pin of an ESP32. I was hoping a simple divider to convert the 6V from the ...
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93 views

Where should I put a 3.3V Voltage Regulator?

I've stumbled across lots of schematics and one thing that I find is almost never consistent is where a certain regulator should go. I'm going to be using the LM1117 series. Should the 3.3V regulator ...
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3answers
60 views

How to prevent voltage regulator board heating up and how thick traces should be?

Im designing a DC-DC voltage step down regulator based off of a switching regulator IC from texas instruments. I have designed the schematic and board accordingly and it should be able to supply 5A at ...
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107 views

What is that component from the ADP5091 Schematic?

I am looking for an explanation what that component does inside of that circuit. It can be found on page 3 of the Datasheet of ADP5091: https://www.analog.com/media/en/technical-documentation/data-...