Tagged Questions

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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2answers
49 views

Voltage regulator lm78xx for 220v?

I can see that the input voltage of the lm78xx series is 30-40v dc . We are looking for a voltage regulators system , that will get the 220v ac , and turn it into a : 3.3v, 12v, 24v, dc . I was ...
0
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1answer
28 views

eliminitaing spikes from the circuit input

Suppose I have a circuit which gets damaged for spikes and high voltages, so that I need to eliminate spikes and high voltages beyond a maximum value, so I have decided for the following two ...
1
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0answers
48 views

Most efficient way to generate 5.0 and 13.25 volts out of 2xAA

Working on an instrumentation device for some friends' lab. The MCU and most of the electronics require 5V @ ~15 mA, and 13.25 volts need to be fed to one side of a differential unity-gain opamp. The ...
1
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1answer
24 views

Pololu S7V8A strange voltage drop when connected to load

I've bought new S7v8A step-up/step-down voltage regulator which should give me on output 2.7-8V. However, when using multimeter I am adjusting correct value let say to around 5V (it really doesn't ...
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0answers
33 views

ceiling fan speed control by current or voltage

the speed of the ceiling fan is controlled by the regulator,now does the speed decrease because the voltage decrease or the current decrease . Pls explain with a circuit.
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2answers
60 views

How does reverse leakage current of a Schottky diode come into play with a SMPS?

Looking at diodes for a low power switch-mode power supply I'm designing. I'm not quite sure what the reverse leakage current value is, or if it's relevant in the component selection.
0
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1answer
35 views

TPS54383 switching regulator components.

I'm trying to build a switching regulator using the TPS54383 dual output regulator, Now I've got most of the components and schematic figured out here. pdf Except the inductor's and diode; I'm ...
1
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2answers
95 views

Simple voltage regulator circuit with 7805c outputs very low voltage

I am trying to make simple voltage regulator circuit from my 9V battery to 5V using 7805c voltage regulator. The schematic looks like this: simulate this circuit – Schematic created using ...
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1answer
43 views

Spice simulation of a motor switching power supply

I'm designing a switching regulator for motor controlling, I have tried this circuit with spice but it does not work: The problem is that the voltage on the load of the regulator never goes down, ...
1
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1answer
36 views

How to calculate theoretically Output Impedance of a Linear Voltage Regulator

I am trying to calculate the output impedance of the following circuit, a linear voltage regulator. What is confusing me is the feedback coming from R1 and R2. I used R4= 500 ohms, R3 = 1K , R1= 25k ...
0
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2answers
57 views

About battery capacity and regulation

For a portable application, I would be using a single 3.7V 2600mAh li-ion cell. The circuit requires 2.5V to 5V to function with the current requirement being 100mA. So obviously a voltage regulator ...
0
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3answers
97 views

48V DC Power Supply Using LM7812 in Series

I want to create a 600W 48 VDC power supply with input taken from the line (220VAC) and so far the steps that I've had in my mind are: Stepping-down the voltage to 15V using transformer with 3A ...
1
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2answers
52 views

LM1084, should I leave the copper area connected to the TAB floating? [duplicate]

I am using the LM1084 in a DDPAK package as a 5V USB voltage regulator on 4-layer board. The TAB of the package is internaly connected to pin 2 (OUTPUT). I am not sure what to do with the copper ...
1
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2answers
50 views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit ...
0
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2answers
47 views

mobile battery charging using voltage regulator?

Circuit shown at http://www.instructables.com/id/9v-USB-charger/ will that satisfy all condition of mobile charging through usb ? what is advantage of circuit shown at ...
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2answers
43 views

Adapter Write Protect for Hard Disk

I need to protect hard disk (sata) for read-only, like SD-card have write protect. Cable sata have channel A & B. Can i cut A or B??? Or any other way? Help me please! Thank everyone
1
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2answers
107 views

Need help with OpAmp and FET choice for a VCVS

I want to build a voltage controlled voltage source that will supply power to a resistive load (\$1.67\,\Omega\$, \$\approx\$ \$7\,\mathrm{A}\$ @ \$12\,\mathrm{V}\$). The load's dissipation will be ...
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1answer
59 views

We're making a bike-powered USB charger and we have (almost) no idea what we're doing

So my friend and I are going to build a USB charger powered by a dynamo. Here is a diagram of what we are planning to do. I have a few questions: 1.) How do we test if the dynamo and breadboard ...
0
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1answer
63 views

Building as Electrolysis tank and I want to regulate a 1.23v into the tank. Any ideas how?

I am building an electrolysis tank and I need some help. I am an architectural student and I have no idea how to regulate voltage or what battery would I need. I want to regulate from the battery into ...
0
votes
1answer
58 views

Buck regulator AOZ1014 getting burned

I am analyzing a buck regulator circuit as shown in following figure. link for datasheet given here: http://aosmd.com/pdfs/datasheet/AOZ1014AI.pdf I have few queries in schematic: Q1. In above ...
1
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2answers
65 views

What is the purpose of a Zener diode added to the output of a SMPS?

I studied circuit diagrams of some computer ATX power supplies. Some of them have got a Zener diode at the very end of 5V stand by line. The picture shows endpoint of the circuit - the SMPS is on ...
0
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2answers
68 views

Input to output differential voltage?

I came across this 7805 voltage regulator. In the datasheet is mentioned the current vs voltage graph. What is Input to output diferrential volatge?
2
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1answer
58 views

Low voltage DC Supercap UPS Design

Most generally I'm looking to design a UPS for a low power DC device given higher voltage AC current, with storage handled by a supercapacitor, or a bank wired in parallel. For my specific case I'm ...
0
votes
1answer
63 views

Low quiescent linear Voltage Regulator [closed]

For a battery powered circuit, I need a VERY low quiescent current voltage regulator. Input voltage is 20V lithium battery, output voltage is 5V (or 3.3V, precision not necessary) for a ...
1
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0answers
72 views

LDO Regulator Overshoot

I'm using an LP38691 3.3V fixed regulator which is overshooting. This wasn't an issue for years, but now a component is being replaced and the current on the 3.3V rail has gone up from 300mA to 500mA. ...
0
votes
1answer
53 views

1A Voltage Regulator - Maximum or output?

I want to design a circuit that has 12V1A output from a battery. I am using a 12V voltage regulator Do I want a 12V 3A Regulator or 12V 1A regulator? If a 12V 1A voltage regulator gives me a better ...
0
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0answers
39 views

Power with Battery + 1wire to i2C

I'm creating a project with Raspberry PI B+ where I will get energy from a truck (12~27v) or/and a solar power (6v 5.6w) to charge a battery and keep the device running until the battery finishes or ...
0
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0answers
35 views

AC to AC Voltage Regulater

Building a hobby related very small and simple project. Currently I run 120V through a household dimmer that feeds an AC to AC (3amp, 25.2VAC output) transformer. Problem is the circuit doesn't seem ...
0
votes
3answers
112 views

Can I put 2 voltage regulators (5V) in parallel to dissipate the heat better?

I connected around 10m of christmas light LEDs to a 5V voltage regulator (lm7805). It gets quite hot, put I can still touch it without burning my finger. So in is within its temperature range (120 C ...
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2answers
42 views

Simulating a linear voltage regulator with ngspice

I am trying to simulate a simple linear regulator using gschem and ngspice. However, my output voltage varies by over a volt as my input voltage goes from 10V to 20V. Can I reduce this swing in the ...
0
votes
0answers
75 views

Help identifying a voltage regulator

I'm trying to build a portable screen so that I can watch movies around my apartment if I need to move away from my TV screen (think a WiiU gamepad or a tablet). I have many raw components and I think ...
0
votes
2answers
65 views

Differing voltages with the same ground?

I have a battery powered radio controlled aircraft. The aircraft runs at 16v. I want to add a video transmitter that is built for 12v. I plan to use this regulator to supply the 12v. ...
0
votes
3answers
73 views

Looking to use an Op-Amp to scale a high-voltage system to a low voltage system

I am looking to scale a voltage of range 30V-120V to a 9V-14V range. I am looking into using an Op-Amp and have found that ideal Op-Amps use a system that cannot take a varying 3rd input as a constant ...
1
vote
1answer
70 views

Microcontroller circuit

I am using a Stellaris EK-LM4F120XL for a project. The project includes an LCD module, servo motor, ultrasonic ranger and a numpad. The LCD, servo and ranger are rated at 5V operating voltage, and the ...
0
votes
4answers
109 views

LM317, basic voltage regulator, why does it get hot when not connected?

I have built this little voltage regulator circuit: circuit diagram I am a hobbyist, so these may well be screamingly obvious questions. I ask because I haven't found the answer to my first question. ...
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2answers
105 views

7809 Linear Voltage Regulator Outputs in Series

I'm building a linear power supply that converts 120VAC mains voltage into multiple 9VDC, isolated outputs. I'm using this transformer that has the proper primary winding and 8 secondaries that I'll ...
5
votes
2answers
305 views

Is this an opamp voltage regulator?

I'm trying to understand the attached schematic, which I came across when repairing an oscilloscope. Am I right in thinking that this circuit is regulating VCC (5V) down to 3.3 and 2.5 volts? Why ...
5
votes
1answer
295 views

Zener diode circuit

When I tried to find current flowing through 1.2k ohm resistor, I am finding 8.33 mA but there comes the problem: I am finding the current through the 1k ohm resistor is 6 mA. What am I doing wrong? ...
0
votes
1answer
68 views

Capacitors vs buck/boost converters

I'm trying to drive high power LEDs with a laptop power supply, and wondered if I should use resistors to limit the extra current, or something like this to limit the current. If I did use that ...
2
votes
1answer
115 views

Boost regulator: Unexpected output voltage

I just finished setting up an LM2577 as a boost converter, and have run into some unexpected issues. For starters, here is the recommended "typical application circuit": My application circuit is ...
2
votes
1answer
106 views

Stable voltage at high current

I am working on robotics project. The drive chassis is powered by a 3-cell 12V 8 Amps battery (I might also go for connecting two batteries to attain speed as my drive motors work at 24V full power). ...
0
votes
1answer
61 views

Voltage regulator

I have a few RC planes and I want to use them upgrade them for night flying. I would like to add EL Wire and/or Arduino + NeoPixels. I am more of a software guy than an electrical engineer so I am ...
0
votes
4answers
55 views

Voltage regulator (LM350) gives no current

I am trying to use a Fairchild LM350 to get 8 volt output. I am using basic circuit (page 5 of datasheet) to do that. I get the voltage I want but whenever I try to measure the current (by putting the ...
0
votes
2answers
86 views

Calculating the Resistor's Power Rating

I'm designing a couple of step-down voltage regulators based on a LM22677 chip (datasheet) and following the example: I want to get 5V and 10V from a 12V supply, but I have concerns regarding the ...
0
votes
1answer
42 views

Voltage Regulation: Cascading vs. Individual

Consider my design: Input power is either 8.4V (VBAT) or 15V (Wall Wart). From there I need several voltages to power all the components on that board. Here is a list of voltages: 5, 3.3, 2.5, 1.85, ...
0
votes
2answers
92 views

Low noise voltage regulation

I have a circuit which currently runs off of either a 12VDC wall wart adapter, or it falls back to a 9V battery if the wall wart adapter is not connected. My circuit currently uses a chip which ...
1
vote
1answer
65 views

Schottky power diode replacement

I'm trying to implement a 12V to 5V step down voltage regulator with a Texas Instruments LM22677, as suggested in the device datasheet (Pag 12, Fig 20). Regarding the selection of the power diode, TI ...
0
votes
1answer
125 views

Dual power supply: two secondaries or series regulators?

I am going to create a simple dual voltage power supply for powering logic (5V) and some stepper motors (12V). What would be a better solution: Would it be to use a transformer with two secondaries ...
0
votes
2answers
59 views

Best way to step down (half) battery voltage for motors

I have a 4S LIPO battery 5800mAH at 14.8V and I want to use it to power some 7.2V motors I have. The Rover 5 Chassis to be exact (https://www.sparkfun.com/products/10336), the only problem I have is ...
4
votes
1answer
83 views

Linear regulator (L7805CV) outputting 5.8V

I am having a pretty strange problem that I am unable to solve. Basically, I am using an L7805CV and it is outputting at 5.8V instead of the specified voltage range in the data sheet. At first I was ...