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Topic: Supplying Arduino Uno using two sources of electricity  (Read 163 times) previous topic - next topic

anisdz

Hello, I have an Arduino project and I am using many sensors, so I need more voltage than the usual pc voltage (usb gives 19V i think) ... Can I use an AC adapter along side the usb ?

if so, the adapter has 12V output and 1.5A. Is it safe to use it ?

groundFungus

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usb gives 19V i think
What gave you that idea?   USB voltage is 5V.

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I need more voltage than the usual pc voltage
What voltages do you need?  What are those sensors?  Can you provide data sheets for them?  Is it more voltage that you need or is it more current?

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Can I use an AC adapter along side the usb ?
You can not connect the outputs of 2 power supplies together.

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the adapter has 12V output and 1.5A. Is it safe to use it ?
Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator.  The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down.  The recommend max power dissipation for the regulator is 1 Watt.  With 12V into the regulator the max current is about 140 mA (1W / (12V - 5V)).  The Arduino uses around 50ma of that leaving less than 90mA (max) for everything else.  I would use a buck converter to drop the 12V to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator.
You will save everyone's time if you read and follow the forum guidelines.  :)          
https://forum.arduino.cc/index.php/topic,148850.0.html
and
https://forum.arduino.cc/index.php?topic=97455.0

SteveMann

Your question is a massive non-sequitur.

USB is 5V.
Arduino's are 5V devices (generally).
Sensors are 5V devices (usually).

You do not need more voltage. More voltage would only fry your components.

You didn't say which Arduino board, but here's a discussion of various ways to power the Uno.

You also don't say anything about the sensors, what they are and how many, but they are usually very low-current devices and the 5V (or 3V if the sensors are 3V devices) can normally power several sensors at the same time.

I am usually so far out of the box that most people don't know what I am talking about.

Please do not ask for help by PM. I will not respond.
If you need help, post a question on the appropriate forum.
Click on Add Karma if I helped you.

Ron_Blain

USB voltage is 5.0 volts (approximately). The best way to run an Arduino is to apply an accurate external 5 volts to the V in pin. The Arduino does have an external power connector which is specified for 7 to 12 VDC and uses the onboard regulator. This applies to the UNO, I have no clue what you have? The best way to run sensors or any uC is with their rated voltage. I can tell you despite the 7 to 12 volt claim that at 12 volts the on board 5 volt regulator gets warm to hot depending on load.

You really need to be specific. Like which Arduino, what sensors and how much overall current you need or want.

Ron

anisdz

What gave you that idea?   USB voltage is 5V.
What voltages do you need?  What are those sensors?  Can you provide data sheets for them?  Is it more voltage that you need or is it more current?
You can not connect the outputs of 2 power supplies together.
Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator.  The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down.  The recommend max power dissipation for the regulator is 1 Watt.  With 12V into the regulator the max current is about 140 mA (1W / (12V - 5V)).  The Arduino uses around 50ma of that leaving less than 90mA (max) for everything else.  I would use a buck converter to drop the 12V to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator.
So i have 2 servomotors both use 5V each, I have also a bluetooth module and MQ2 sensor and a buzzer all of them use 5v as well ... That's why i thought that usb voltage isn't enough for all of them, am I wrong ?

anisdz

Your question is a massive non-sequitur.

USB is 5V.
Arduino's are 5V devices (generally).
Sensors are 5V devices (usually).

You do not need more voltage. More voltage would only fry your components.

You didn't say which Arduino board, but here's a discussion of various ways to power the Uno.

You also don't say anything about the sensors, what they are and how many, but they are usually very low-current devices and the 5V (or 3V if the sensors are 3V devices) can normally power several sensors at the same time.


Hi, I am using Arduino uno and 2 servomotors, bluetooth module, 1 gas sensor and a buzzer ... can my computer power all of them at the same time ?

groundFungus

You will need external power for the servos.  That power source will need to be able to supply the stall current of the servo motors.  That is about 1A per servo for small hobby servos more for the larger servos.  A 4 AA cell battery pack is a popular power source for servos.  Connect the + of the battery pack to the servo plus and the - (minus) to the - of the servo and to the Arduino ground.

The gas sensor heater needs nearly 200mA.  You may be able to power that sensor from USB, but not from the internal 5V regulator powered by a 12V wall wart.  See reply #1.  You could power the heater from a 12V to 5V DC-DC converter as well as the Arduino.

The buzzer can be powered by the Arduino or USB.

You will save everyone's time if you read and follow the forum guidelines.  :)          
https://forum.arduino.cc/index.php/topic,148850.0.html
and
https://forum.arduino.cc/index.php?topic=97455.0

anisdz

You will need external power for the servos.  That power source will need to be able to supply the stall current of the servo motors.  That is about 1A per servo for small hobby servos more for the larger servos.  A 4 AA cell battery pack is a popular power source for servos.  Connect the + of the battery pack to the servo plus and the - (minus) to the - of the servo and to the Arduino ground.

The gas sensor heater needs nearly 200mA.  You may be able to power that sensor from USB, but not from the internal 5V regulator powered by a 12V wall wart.  See reply #1.  You could power the heater from a 12V to 5V DC-DC converter as well as the Arduino.

The buzzer can be powered by the Arduino or USB.


So all I need to make both servos to work is a 4A battery ? 1 battery for both or 1 battery for each ?

Sorry im newbie and my project is due to Sunday:P 

groundFungus

#8
Oct 07, 2020, 06:43 pm Last Edit: Oct 07, 2020, 06:43 pm by groundFungus
You only need one battery pack to serve both servos.
You will save everyone's time if you read and follow the forum guidelines.  :)          
https://forum.arduino.cc/index.php/topic,148850.0.html
and
https://forum.arduino.cc/index.php?topic=97455.0

DVDdoug

Just some quick basic electronics for you...

Ohm's Law determines the relationship between voltage, current, and resistance.   Resistance is the resistance to current flow...   More resistance means less current.

In most situations the voltage is approximately constant.   For example, there is always 5V on the USB port and 120 or 240V at your wall outlet but no current flows until you plug something in and turn it on.   A 1000W hair drier  "draws" more current than a 100W light bulb and if you plug-in (and turn-on) two hair driers you'll draw too much current, the circuit breaker will blow, and the voltage will drop to zero.

You won't find a resistance spec for a servo motor, but you should have a current spec (Amps or milliamps).

Power (Wattage, related to heat) is calculated as Voltage X Current.


anisdz


Paul__B

The best way to run an Arduino is to apply an accurate external 5 volts to the V in pin.
No, the "Vin" pin is the one you do not use.  You apply 5 V to the "5V" pin (and of course, negative to ground).

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