Okay to hook 5V output right into the aref?

My circuit runs only off the uno's 5v output and I'm on usb. I've noticed some drooping (my new handy dandy dmm says around 50 mv) and it throws off my potentiometer input, since now the max is a few dozen mv fewer than 5v. Can I just run a wire to aref to compensate? I found a really old forum post for 3.3v saying to use a 5k resistor, but is it different for 5v?

That is the default connection. You can use the internal 1.1V reference for a stable (but uncalibrated) value.

Neywiny:
I've noticed some drooping (my new handy dandy dmm says around 50 mv)

and it throws off my potentiometer input

Can I just run a wire to aref to compensate? I found a really old forum post for 3.3v saying to use a 5k resistor, but is it different for 5v?

How did you measure that.
I just measured ~4mV between the Aref pin and the 5volt pin.

What do you mean with "throws off".
Don't see what problems a lower Aref could have.
Only that 1023 is reached with a slightly lower input voltage.

Not wise. You will short the internal Aref switch of the MCU.
The 5k resistor is to try to protect the pin if a mistake in setting the Aref to internal/external is made.
Leo..

I put my probes on my pot's + and - terminals (also tested the wires going to 5v and gnd, and a random rail on my breadboard). As I turned on more functionality of my circuit, all of them led's, I'd notice a few millivolts drop for each one. Turn off the led, it rises back up.

I'm sending the value over serial and at full load it's only reading maybe 995 or so, bounces around a little. Again turning off the led's, jumps back up to 1023.

So I figured if I sent the 4.95 whatever volts to the aref, I'd basically automatically scale it. I guess that's not what would happen. I'll have to find another way then.

You could, so long as you could be sure that it never gets higher than the 5V rail of the Arduino. That blows things up very quickly. Your idea is the true intended function for that pin on the Arduino.

A better solution is to make sure that the Arduino's 5V supply is electrically "close" to the 5V that the pots get. I would make them powered directly from the 5V pin and keep everything else off that wire.

I found an ac adapter that fit (12v, so still fine) and I've read the 5v pin at max of 5.012 though with the new power supply, so I'll do more testing in case it was a slip up but if over 5 fries it maybe I'll just try the other methods until I'm 100% that it won't go over 5 again. I just don't have anything else at the moment that can do 5v, maybe I'll fabri-cobble something out of a broken usb cable.

Neywiny:
I put my probes on my pot's + and - terminals (also tested the wires going to 5v and gnd, and a random rail on my breadboard). As I turned on more functionality of my circuit, all of them led's, I'd notice a few millivolts drop for each one. Turn off the led, it rises back up.

I'm sending the value over serial and at full load it's only reading maybe 995 or so, bounces around a little. Again turning off the led's, jumps back up to 1023.

So I figured if I sent the 4.95 whatever volts to the aref, I'd basically automatically scale it. I guess that's not what would happen. I'll have to find another way then.

That's normal. Wires, breadboard, it all has some resistance. So you could see a few mV drop.

A pot with Arduino's A/D is ratiometric, so exact voltage is irrelevant.
A drop in A/D value means there is something wrong with your setup.

Don't try to fix one problem with another potential problem.
Post a picture. There must be something wrong with the setup.

Neywiny:
I found an ac adapter that fit (12v, so still fine)

No, it's not.
Most Arduinos run on 5volt, so 7volt has to be dropped by the 5volt regulator.
With that supply voltage you can only draw ~100mA from an Uno before the regulator overheats.
Better use a 7.5volt or 9volt REGULATED supply, or a 5volt cellphone charger connected to the USB socket.
Leo..

pictures are as follows, the last being the schematic I added the pot to




In case the jungle of wires is too thick, the pot's 5v and gnd lines are pulled from the other side of the board before any other devices.

I've felt the regulator IC, for the 15 seconds to a minute at a time or so that I'm running each test, it's fine. For anything long term, sure something else works better, but at the moment I don't have anything else. I'm not overflowing with regulated and unregulated and voltages and stuff power supplies.

If turning the LEDs on/off makes a big difference in max pot value, then there must be someting wrong with the 5volt supply going to the pot.
Try another wire between Arduino's 5volt pin and breadboard, and/or another contact/area of the breadboard.
Leo..

I'll give that a whirl when I get back into it, thank you for the help.