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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TL431 Constant current source

I have few doubts regarding TL431. Please correct if i am wrong.. TL431 can be used to generate voltages from Vref to 36V. Output voltage is taken across diode in reverse biassed condition. ...
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2answers
79 views

How to extend the input range of a linear voltage regulator?

I need to generate a fair bit of current (up to 2A peak, much less average) in the 6V-15V range for driving MOSFET gates, and also generate 5V (less than 100 mA) for an MCU, from an input that may be ...
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4answers
415 views

How can I reduce voltage from 40VDC to 5VDC?

I'm working to power a micro controller that requires something like a USB power supply - 5VDC with a normal draw of .75 - 1 amp but could possibly draw as much as 1.5 amps. I know that with smaller ...
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2answers
155 views

What's wrong with an opamp as a voltage regulator?

I was watching a video about power supply design and it was mentioned that an opamp being used as a regulator like this: simulate this circuit – Schematic created using CircuitLab in ...
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2answers
69 views

SMPS with two outputs ,12v 3A(max) , 24V 2A(max)

Hi all , I am new to designing circuits. I am building an SMPS using the fairchild Semi FSGM300N Power switch. here is the datasheet http://www.farnell.com/datasheets/1526530.pdf they have given a ...
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2answers
236 views

Why don't people tend to use voltage dividers or zeners in front of linear regulators

After seeing some students yesterday that tried to use a voltage divider instead of a regulator to provide a sensor with a lower power supply, with predictable results, I started wondering about this ...
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4answers
384 views

When would I use a voltage regulator vs voltage divider?

When would you use a voltage regulator vs a resistor voltage divider? Are there any uses for which a resistor divider is particularly bad?
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3answers
85 views

Shunt Resistor on output of Voltage Regulator? [closed]

I was looking through a popular circuit on Sparkfun and trying to lower the power consumption of the device. I found that the outputs of their regulators are shunted to ground with a 300-ohm resistor. ...
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1answer
59 views

Is it possible to use buck boost converter at the same time?

I have a input source from 50mV to 4V and I want a fixed/regulated voltage of 3V. Input voltage is varying every time so in order to achieve the 3V I have to implement Buck as well as Boost converter ...
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1answer
59 views

Light Organ — Need help with LED grid

I'm building a light organ for a school project. I've got a crossover to separate the frequencies, now I need to make an LED grid. The input will be an constantly changing analog signal (whose ...
2
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1answer
52 views

Can a Zener diode be used in place of a Schottky?

I want to use a LM226677 Voltage reagulator to achieve a step-down converter from 12V to 10V. However, in a Schottky diode is used reversely polarized at the output of the LM22677, and the datasheet ...
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2answers
80 views

Overcoming voltage drop in a battery

I want to use this battery for my Arduino Uno: ...
0
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2answers
58 views

What are the downsides of using a LM7805 with a 11.1v Li Ion Laptop battery to charge a USB device?

I want to use my thinkpad battery(11.1v) hooked up to a LM7805 to charge a USB Device. What are the downsides to such a setup?
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3answers
1k views

Why too many capacitors in parallel for Vdd supply net? Can't we just add all to replace with one big capacitor?

I have given the image of Basys-2 board's power regulator IC and filters connected to it in schematic. This is just an example but this is pretty much a similar filtering design for most of the supply ...
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1answer
50 views

How my ac-dc adapter gives constant voltage and current? [duplicate]

I have multiple ac-dc adapters, one with variable voltage and the others for electronic devices. written on them they give specific voltage and current, How come? Doesn't the current change with the ...
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1answer
59 views

Power Supply for LED Project

I am working on a project where I have to power a 5 meter long LED strip (https://www.sparkfun.com/products/12022) and 54 3.4V 20mA LEDs and control them all from an Arduino. My current idea was to ...
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2answers
123 views

Can I use 12V voltage regulator and a variable 0 to 30V DC power supply to control my 12V DC motor speed?

I've got a 12V DC motor with: Output power: 3.4 watts Rated speed : 170 RPM Rated current: 0.9A Currently I have a variable voltage DC power supply which can vary the voltage from the DC power ...
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1answer
88 views

How does the PWM from MCU get translated into a output voltage as in Power Electronics [closed]

Background: I am preparing for a full-time employment starting in May. I am coming from a computer engineering background so I only have some working knowledge regarding EE. The job duty is Firmware ...
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1answer
25 views

voltage regulator BD9C401EFJ

I am using the BD9C401EFJ for 9V to 5V conversion(with enable pin pulled high). So - I/p = 9V and o/p = 5V. I was just doing some expts and saw that when I give no i/p, and I give 5V at the o/p side ...
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1answer
64 views

Correctly measure L7805ACT regulator output

I am trying to measure the output of a L7805ACT voltage regulator (datasheet) with a multimeter, without any additional parts (no caps, etc, just the regulator). I'm using a regulated wall adapter ...
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3answers
49 views

Voltage regulator for DC motor

I'm trying to regulate the voltage of 9 volts battery to DC motor but didn't work. This is my scheme: The original scheme is for led and just wondering why it didn't work for DC motor. Here is the ...
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0answers
49 views

L7805 Not Outputting Current from Solar Panel

This question goes with a question I had a week or so ago here if anyone is interested. L7805C/L7812C Voltage Regulator with 22V Solar Panel Not Outputting a Constant Voltage Anyway, here are the ...
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4answers
103 views

Voltage regulators

I would like to ask the function of the capacitors arranged in parallel to the LM7805 voltage regulator and if i can get an explanation of the resistive divider coonected to the LT1528 voltage ...
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3answers
118 views

Regulated +5V drops when relays are switched on

A regulated power supply RAC02-055C/277 provides 5V to an Arduino driving 2 relays. The power supply is rated to provide 2W of power. Connecting a multimeter between one of the leads of the power ...
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1answer
33 views

Windmill generator voltage-regulation with clamping diode

I am making a windmill powered generator. The charge controller I have is rated for a maximum input of 15V. I want to protect the controller in the event of high voltage spikes produced in a wind ...
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5answers
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To what extent are “pure sine wave” power supplies marketing spin?

Recently, I've noticed a trend in power supply manufacturers touting their PSUs (generator or battery inverter etc.) as having a pure sine wave output. I've also seen people saying that warranties ...
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0answers
83 views

L7805C/L7812C Voltage Regulator with 22V Solar Panel Not Outputting a Constant Voltage

First, here is my solar panel: http://www.amazon.com/Instapark%C2%AE-Black-Mono-crystalline-Charge-Controller/dp/B005LR9IOG And the regulator: ...
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2answers
127 views

Voltage regulator help

I need help with what is probably a very simple question that I don't know. When you put 12v at 10 watts and bring it down to 5v with a regulator would the wattage change? And just say the regulator ...
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3answers
102 views

Voltage of Voltage Regulator changes when a Potential Divider is added

A Keithley 2400 Source meter is used to provide +7V. Using Fluke 179 Multimeter, the potential across the source meter leads is 7.00V. The source meter is then ...
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0answers
55 views

Why does this voltage error amplifier output always reach its saturation voltage?

Why does the voltage output of both amplifier (Vm1 and Vm2 as shown in picture) always reach its saturation voltage?
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2answers
712 views

Simple electrical circuit won't work

Simple NPN switching circuit to open a relay circuit, first NPN switching part didn't want to work (3rd PCB and endless times of trying). Circuit wizard diagrams, I split its first part to figure out ...
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1answer
56 views

Creating a powered USB hub, trying to drop my voltage from 12v to 5v (AC/DC converter I have outputs 12v)

I'm trying to build a powered USB hub without buying additional parts. So finding old electronics lying around the house kinda deal. Anyways I have a 4 USB hub that I took apart to find the PCB was ...
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1answer
114 views

Powering the MCU (basic), is this circuit suitable?

Shown is a basic circuit diagram to power a MCU. I am using the recommended caps for the test circuit for the regulator. Should I put a diode between the +ve terminal of the power source and the ...
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1answer
56 views

7V or 12V Power Supplies for Arduino

The recommended input voltage for Arduino is 7-12V. Given that both 7V and 12V power supplies (AC-to-DC converters) are available, which voltage will be more suitable/practical? Could be in terms of ...
0
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2answers
59 views

Zener Diode - Vz0

Theoretically, what is the importance of Vz0 in the following figure. When modeling the zener diode, why is Vz0 used over the diode's given Vz? For modeling, I was given the formula Vz = Vz0 + ...
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3answers
85 views

Murata OKR-T/10 pulldown value

On the Murata OKR-T/10, the data sheet specifies a 49kohm pulldown resistor but I've seen people using a 1k. Is there a more correct value or does anything 1k or above work just as well?
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1answer
75 views

Spikes in voltage rails

My circuit has 3 sections. The supply is 9V. This goes to a regulator (5V), another regulator (3V) and the 9V is connected directly also to a BLDC. Now, when I start the motor (this is done in brake ...
2
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1answer
106 views

Does USB require protection if it is only connected to the regulator input?

I have the following schematic powering my circuit. Is it required that I protect the USB power pin with some fuse?
2
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1answer
73 views

Laser controller project

The context is that I want to build a tunnel laser effect, that modulates the angle of the cone according to a sine wave. The purpose being, to create a cool Borg weapon effect for a Star Trek Borg ...
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0answers
46 views

Activating Triac, signal conditioning

I need help with the following circuitry. Basically it is a correction of a bug in one of my company's products, an automatic glass door controller. What it is meant to do is when I give the lock ...
3
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5answers
341 views

Are opamps as a voltage regulator effcient?

If I setup an opamp in a non-inverting configuration as follows: Vrail+ is 7.5V, Vrail- is GND (0 V) Vin is 2.5V, Vout = 3.3V (in other words, the gain, aka, 1+R2/R1 is 1.32 [V/V]) Iout = 100mA ...
0
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1answer
94 views

Input voltage of LM317 drops when lead acid battery is connected on output

I have built a voltage regular circuit with LM317. Its input is connected to my solar panel. As in many circuit examples, there is a voltage divider to bias the adjust pin. Also, I have connected a ...
0
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1answer
50 views

A voltage regulator that is controlling a voltage

My scenario is that I am having a circuit which having 12V as the input voltage and works beween 8V to 15V. I want to limit this circuit in a way that if the input voltage drops below 12V criuit ...
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3answers
129 views

How to use a GND transistor to turn off a voltage regulator?

Using an 5V out voltage regulator LM7805/NTE960 with a project that doesn't always need to use the regulator and may run on a battery. The regulator will always draw some milliamps from the battery ...
3
votes
2answers
187 views

Is a USB Charger a regulated supply?

I'm trying to design a circuit based on an ATMega328 (from an Arduino stand-alone type kit), and was planning on adding a USB connector and powering the board from a generic USB phone charger type ...
2
votes
2answers
211 views

Transformer coils in series, switching for 12/24V. EMF killing my circuit?

I'm making a little linear PSU for my lab. Based on the good ol' LM338K. I fried one last night and I'm still trying to figure out why. I think it might be EMF from my transformer. I have a ...
2
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1answer
103 views

Extracting the Most Energy From a Capacitor

I have a 5V super capacitor which I'm trying to extract the most energy from in the most efficient way possible. This capacitor is tied to the input of some regulator (which is the question of this ...
0
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3answers
124 views

48V Battery Voltage Regulator

I initially designed a circuit that would take a 12V battery as its power supply and power up a comparator circuit that would turn on/off a 12V fan based on temperature. This 12V battery could have ...
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1answer
60 views

Use voltage regulator instead of zener to protect GPIO

I've read several articles about protecting 3.3v GPIOs from unregulated over voltage, all of which involve using a zener diode, a diode for reverse protection and resistors in some fashion. example 1 ...
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3answers
68 views

Converting variable voltage to constant voltage / variable current

I'm using solar panels + a micro wind turbine to charge a decent sized LiPo battery using this circuit - http://www.adafruit.com/products/390. The problem is that the solar/wind stuff will produce a ...