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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3
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1answer
3k views

220v AC Fan regulator

i need to regulate the speed of a noisy kitchen FAN from a microcontroller (arduino board), i have been looking around and checked a lot of websites and schematics, and i think the solution should ...
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2answers
4k views

LM317 getting hot

Should an LM317 (specifically a TI LM317MQDCYR) rated for 500ma output current really be getting hot to touch when only pulling 170ma at 5V? Package is SOT-223, input is 9V. Is this normal?
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3answers
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Need ideas for 5->3.3 voltage conversion for micro SD cards

I'm thinking about connecting a micro SD card to my ATmega162 perfboard, but for that I need 3.3 V source which can provide up to 100 mA. Most obvious option would be to run the whole board at 3.3 V ...
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4answers
807 views

Understanding when to use basic Components

So I understand AVR assembly for the most part, and generally understand the overview of microcontrollers. but when it comes to specific components (besides the obvious stuff like resistors/batterys) ...
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6answers
2k views

Regulator solution for 5 volts at +2ish amps

I have been looking at a lot of different regulators. Generally speaking switching regulators will give me a wide range of input voltages at the out put amps I am looking for with added efficiency. ...
3
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7answers
3k views

how to drive a 1.35V led with a 1.4V AA battery

I would like to mount a TSAL6400 led on a single AA size battery box, with a simple ON/OFF switch. My problem is that the LED needs exactly 1.35V to function at its rated brightness. At this voltage ...
0
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1answer
139 views

Is this a good way to power my camera?

I have a Canon SX210 IS which has not a connector to use a external power supply. So I wanted to connect "my" power source to the pins the battery usually touches. In the back of my camera, it says 4....
2
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3answers
753 views

Inexpensive switching regulator with internal inductor & diode

I'm trying to minimize part count and cost of my project. It needs to have a 6V power rail with about 1.5A peak current from a 12V input. I'm shying away from a linear regulator because of the power ...
16
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2answers
4k views

How does a zener diode and a resistor regulate voltage?

I'm having trouble understanding the simple voltage regulator that can be built using a zener diode (from section 2.04 in the Art of Electronics). I know that it would be better to use amplifiers, et ...
5
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4answers
384 views

Obtaining 15 V from a single lithium polymer cell

I want to get 15V output from a 1 cell lithium polymer battery which has a voltage range of 3v-4v. I am thinking about using a 34063 to accomplish this. But will this work over a 1v range or do I ...
8
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2answers
5k views

What's the difference between a “Switching Regulator” and a “UBEC”

I want to regulate the voltage from a battery down to 5v to power an Arduino and a Wi-Fi webcam. I’m not too keen on a linear regulator as a lot of power is wasted, so that’s led me to look at ...
28
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2answers
43k views

Capacitor Sizes for 7805 Regulator

It says in the datasheet these values in this picture: But I've also seen it with these values: So what values should i use or doesn't it matter? And its for when its first starting.
16
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6answers
44k views

How do I convert 9 V DC to 5 V?

What's a good way to reduce the output from a 9V battery to the 1.8V to 5V required by an ATmega328 controller? The context is a small robotics platform with low power requirements (very slow movement)...
0
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3answers
472 views

Is there a voltage regulator IC that takes PWM input?

I am looking for a small IC that provides a regulated dc voltage based on the duty cycle of the input. This is probably asking for a lot but does anyone know if one exists. Essentially I need a low ...
15
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2answers
35k views

7812 minimum input voltage?

On the datasheet it doesn't mention an input voltage. Must the input voltage be higher than the output voltage or does it increase to 12 V if I input 8 V for example? If so, what is the ...
8
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5answers
9k views

Is there a Dual Voltage Regulator?

I am working on a circuit design that has multiple IC's on it. My MCU requires 2.5-3.3 VDC for it's power. Another IC that I am using requires 5V for it's logic power. So what is the cheapest and ...
4
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5answers
488 views

Can I use an amp before my voltage regulator to ensure I get 5v?

I have a 4.8v battery pack and I made a simple power supply with a L7805CV voltage regulator, which has a 2v dropout. So I'm only getting like 3.5v out. Is it possible to throw an op-amp or something ...
4
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3answers
653 views

Why is my power supply putting out 3.85v instead of 5v?

I made a power supply using two 47uf electrolytic (aluminum, I believe) caps and a L7805CV 5v power regulator. I also added a 100ohm resistor and an led to vout. I'm using a battery pack of 4 NiMH AA ...
2
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3answers
354 views

What will happen if I feed this rangefinder 3.3v?

I have this rangefinder http://www.hobbyengineering.com/H2951.html and my MCU is running on 3.3v (MSP430G2231), will this thing work poorly if I feed it 3.3v instead of 5v? I really don't want to have ...
3
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4answers
781 views

3.3V @ 10mA from 5V - 35V

Any ideas on how to get 3.3V from 5V - 35V at a low 10mA current level? 3.3V need not be precise. It can be 3.5V or 3V, it is powering a small microcontroller. I'm looking for a small and cost ...
3
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2answers
886 views

Replace broken 79M12 and 7805 voltage regulators?

I have an old computer, an ABC80 from the late seventies or early eighties, in which I have reason to believe one or more of the voltage regulators are broken. Now I wonder, what may be suitable ...
6
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3answers
37k views

Use diodes to obtain lowered DC voltage?

I am building a digital voltage gauge for my motorcycle for fun. I am buying a nice little display which has common ground, so that I can provide 5 and 12 volts from the same source. I was hoping to ...
9
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7answers
4k views

How to keep a linear regulator cool without an actual heatsink?

I want to use a linear regulator for some application, it's in a SOT-223 (not SOT-89) package. How do I keep it cool, preferably without a bulky heatsink? The regulator may be dissipating 2-3W of heat....
15
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2answers
7k views

Is it normal for DC wall adapter power supplies to provide voltages above the nominal ones?

When I measure a 9V DC wall adapter power supply with a multimeter it shows 11.8V. When connected to my board this voltage lowers to 10V. Is this normal? Should I be afraid of toasting my 1117CD-5.0 ...
4
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6answers
3k views

What's causing this high frequency ripple on the output of my LM317?

I'm using an LM317T to regulate 5 V to 3.38 V for a microcontroller. R1 is 330 ohms and R2 is 560 ohms. There isn't any input capacitor and the output capacitor is 470 µF 25V, because I ...
3
votes
1answer
562 views

Cheap 500mV reference

For a project, I need a 500mV reference. Some requirements: Relatively low cost. Small size. Preferably surface mount. Supply from 4.8V to 25V. Accuracy ±5% or better Stable over voltage (that is, ...
4
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2answers
623 views

Best Circuit Design for a 12VDC Wall-Wart > Ouput Voltage of 1.5V (Replacing Alkaline Batteries)

I have multiple stationary baby items for my son Oliver that require a serious supply of batteries each month. I would like to hook a few of these stationary items up to wall warts to conserve the ...
4
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4answers
484 views

Low Profile Power Dissipation

I have a project where my power supplies are giving me a bit of a headache. I have three voltage regulators that I am trying to run from a single bench power supply. There are two 3.3V regulators, and ...
7
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3answers
35k views

Difference between Mosfet and Voltage Regulator?

I'm new to electronics and was wondering what was the difference between a Mosfet and a voltage regulator?
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3answers
212 views

Close enough for voltages?

I want to extend the use of a camera. The camera currently uses a special li-ion 3.7V 1000 mAh battery. I could grab a couple of those batteries, wire them up in parallel, and that'd work just fine. ...
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2answers
1k views

Low Voltage Shunt Regulator

Hey, I came across this Low Volatage Shunt regulator on a Hobby RC forum, I am trying to figure out how the resistor Values are Calculated, http://www.rcgroups.com/forums/attachment.php?attachmentid=...
6
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2answers
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iPod Car Charger w/ Audio Out

I have been working on a circuit design that would allow me to charge my iPhone/iPod classic 120 GB from my car. I am going to use power from the back of the cigar lighter sockets and put it into this ...
4
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6answers
4k views

Converting 24VAC to 5VDC - Need transformer demystification

I've got an automatic litterbox that 'needs' to be hacked for better control. As it ships, it comes with a 120VAC to 24VAC (300 mA) wall wart that drives the two motors in it. I'm trying not to change ...
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4answers
2k views

dc level shifter

I am a high school student. Please help me, i want shift a 24 volts at the input to 6v on the output!! i need a dc level shifter but i dont know its contents!!
6
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3answers
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Can I Filter This Split Power Supply?

I've got a battery powered synth that uses two 9v batteries to make a split rail power supply (±9 and ground). I'm trying to use a regular AC-DC power adaptor to replace the batteries. The adaptor ...
26
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6answers
21k views

How does an LM7805 voltage regulator work?

How do most voltage regulator ICs work? Are they the same as hooking up a variable resistor and a voltmeter and turning the knob until you get the desired voltage?
28
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6answers
24k views

How to convert AC to DC

I am designing a circuit that needs to output 5VDC @ 1A. I'm trying to use a wall transformer to step the voltage down to 12VAC. The next step is the diode bridge and ripple capacitor. The ripple ...

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