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Author Topic: Connecting multiple things to the 5V pin.  (Read 912 times)
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Hello all. I've got a newbie question about how much I can connect to the 5V supply pin on my Arduino. I do hope this is the right subforum for this, please direct me if it isn't. And please excuse the simplicity of this question. I'm very new to electronics and mildly terrified of killing the ATMega on my Arduino.

So...

In the Arduino tutorials, to read the the voltage from a potentionmeter as a value, I connect the 5V pin to one side of the pot, the other side to ground, and the middle pin to an analogue pin on the arduino. Then I can do an analogueRead on the analogue pin and get a value for the pot.

If I want to use one of my common anode 7 segment displays, I connect the 5V pin to the common anode, then each of the segments cathodes to a different digital pin on the arduino. Then if I set any of those pins to low, that segment lights up.

Ok, all well and good.

Here's the question: Say I want to have the pot and the 7 segment hooked up at the same time - let's say for instance I want to have the 7 segment display, display a number from 0-9 representing the position of the pot, is it ok to just connect the 5V pin on the Arduino to the power rail on a breadboard, and then just connect both the pot and the 7 segment's anode to this? I'm guessing it will probably work, but will they affect each other, in terms of current draw, voltage drop etc.? Will I find my display getting brigher as I turn the pot or something funky like that? Is there any danger to the controller in doing this?

I guess I could also just connect either the pot or the 7 segment display's anode to another of the digital pins on the Arduino instead of the 5V pin, and set this to output HIGH, and then that pin would source the current for whatever was hooked up to it, but would there be any point doing this? Would it be better or would the overall effect be the same?

Again sorry for the extreme simplicity of this question, I'm having trouble finding resources to answer very basic question like this, so if anyone knows of any please direct me. I have looked through the tutorials but I couldn't find any examples for this specific information, where 2 things are connected to the 5V pin.
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Depending on the value of the potentiometer it will have minimal effect on the circuit. 5V and 1k doesn't make for much current, and a larger value pot will draw even less current - you are using the pot more as a voltage sense than for current anyway...

The seven segment display will be more of a source of current draw. Though you will have to limit the current (to limit the voltage across the segments) with a resistor going to each Arduino pin.

I have a little shield that I made to play with analog and LEDs that has 2 pots and 7 LEDs that all work at the same time from the same 5 V on the Arduino. As long as you don't try to run too much current through any pin and you are drawing less current than the 5V pin can supply you should be fine.
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