Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [5v]

Deprecated tag. Do not use in the future.

Deprecated tag. Do not use in the future.

347 questions
23
votes
4 answers

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 amperes, while most of them would draw less than…
Velimir Tchatchevsky
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18
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3 answers

How do I use a 5V relay with a 3.3V arduino pro mini?

I'm using a couple arduino pro mini's (3.3V) for a home automation project and want to add relays to the final PCB design to switch some stuff on and off. Since I want to use a 5V relay like this: HF 46F 5V, Miniature HF power relay, 5 V, 1 NO 5 A I…
Blacky
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14
votes
3 answers

Convert 5VDC to 400VDC

I'm currently making a geiger-counter and therefore I need to crank my 5VDC up to around 400 VDC, the current is very low, around 0.015-0.02 mA. What would be the best way to generate 400VDC from my 5v source?
Majorleq
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8
votes
3 answers

5V ups circuit oscillating?

I'm trying to design a 5V UPS. Power to load should switch if line voltage falls below about 4V. Battery voltage may be from 3.8 to 5V. I'm simulating in LTSpiceIV. I'll be using mosfets to supply battery power to avoid schottky voltage drop.…
Indraneel
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8
votes
1 answer

which is better? 5V or 3.3V as the supply voltage

I am about to design a new microcontroller based project. I checked all components (few) and all can operate at 3.3V or 5V. the microcontroller itself can also operate at 3.3V or 5V (pic micro at only 4MHz oscillator). Well, the question is, what…
fhlb
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7
votes
4 answers

How to amplify electret microphone to range from 0-5V with bias of 2.5V?

I'm new to op amps and have tried many circuits but don't get the results I expect. I know I must do some math but I get so confused. I thought my question is really simple but it turns out it's not. I just want to amplify an electret mic to 5V.…
Roelf Daling
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7
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1 answer

Open collectors & 74LVC245

I am trying to interface a PS/2 keyboard to a MSP430 for a toy. The PS/2 keyboard runs off 5V, but the MSP430 microcontroller runs off 3.3V. So I have a 74LVC245 level shifter to convert between the two. Now I have this, however, I have discovered…
David Given
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1 answer

Voltage Level Shifting

I know there are similar questions on the site, but I wanted to ask it from a somewhat different perspective. I've got a 5V device (Device A) that can operate at 3.3V. I've got a 3.3V device (Device B) that does not have 5V tolerant inputs. I want…
vicatcu
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6
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2 answers

5V Tolerance of 3.3V OUTPUT pin

Let's assume the following scenario: uC (@3.3V VDD) drives an I/O pin HIGH 3.3V (just to be clear, it's not an open-drain pin, so the p-channel mosfet of the output pin is actually driving the pin to VDD level) Pin is also rated as a 5V tolerant…
Nitro
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6
votes
5 answers

7805 regulator outputting 4V instead of 5V

I followed a tutorial on Sparkfun to put together a 5V power supply. But for some reason I'm only reading 4V coming out of the regulator. I know it's not the regulator because this is the second one I've tried. I checked the data sheet to make sure…
Michael
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6
votes
2 answers

3.3v input to Arduino digital pin

Is it safe to bring a arduino digital input pin to high on a 3.3v input..from the 3.3v output of the arduino pin? Because, I need to reset a 3.3v device on one end..and get the arduino to know about the reset too..but I am too lazy to involve…
Raaj
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6
votes
3 answers

Change voltage without consumption

Is it possible to change voltage without consuming power? I have a 5V Arduino circuit that makes use of a wireless chip (NRF24L01) that runs on 3.3V. My current approach to get 3.3V out of a 5V source is a voltage divider using a two resistors. It…
Socrates
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5
votes
2 answers

5V Regulator Power Dissipation

I am using a 5V regulator (LP2950) from ON Semiconductor. I am using this for USB power and I'm feeding in 9V from an adapter. USB requires maximum of 500mA right? So the maximum power dissipation in the regulator is (9V - 5V) * 500mA = 2W. My…
David Norman
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5
votes
1 answer

Pogo Pins Schematic

I have a Galaxy Nexus phone which has pogo pins: I have determined which pins are PWR and GND but I don't know what the third pin is. I assume it is for the dock feature of the phone so it knows that it has been inserted into a dock. I'm not sure…
Nick
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5
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2 answers

Capacitor selection for LM3940 LDO regulator

My project requires 3.3v for operation. For the simplicity I want to power it with USB sources and this makes me to add step-down converter/regulator to get 3.3v from 5v line (let's omit input power filtering for a moment). I've chosen LM3940…
Drobot Viktor
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