user77556: Why won't my MicroServo run at external 5v power supply? , I've tested my power supply and can light up 1 LED and also run the servo mainly on arduino and it works just fine. Im currently using a computer power supply using the red wire(5v). I'm not very knowledgeable with voltage and stuff and im hoping someone can answer.

and here is my power supply...

I've checked the power supply terminals but nothing is wrong there. Also, i've tried 10k potentiometer to be supplied by it but when i read it in serial.begin it just reads "0, 0, 0, 0, 1023, 1023, 1023, 1023" over and over again. Sorry about the formats im still new.

user52659: The image you uploaded shown quite clearly that you have not connected the grounds between the Arduino circuit and the servo circuit. In order for it to work, the servo should reference the signal line to ground, currently only PC power supply is providing ground, so the Arduino signal line is floating.
Check out the attached image and connect the GND as shown in dotted yellow line.


77556: <p>Why won't my MicroServo run at external 5v power supply? , I've tested my power supply and can light up 1 LED and also run the servo mainly on arduino and it works just fine. Im currently using a computer power supply using the red wire(5v). I'm not very knowledgeable with voltage and stuff and im hoping someone can answer.
<a href="https://i.stack.imgur.com/4ccRD.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4ccRD.jpg" alt="enter image description here" /></a></p>
<p>and here is my power supply...
<a href="https://i.stack.imgur.com/z8Mmo.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z8Mmo.jpg" alt="enter image description here" /></a></p>
<p>I've checked the power supply terminals but nothing is wrong there. Also, i've tried 10k potentiometer to be supplied by it but when i read it in <em><strong>serial.begin</strong></em> it just reads <strong>&quot;0, 0, 0, 0, 1023, 1023, 1023, 1023&quot;</strong> over and over again. Sorry about the formats im still new.</p>
 52659: <p>The image you uploaded shown quite clearly that you have not connected the grounds between the Arduino circuit and the servo circuit. In order for it to work, the servo should reference the signal line to ground, currently only PC power supply is providing ground, so the Arduino signal line is floating.</p>
<p>Check out the attached image and connect the GND as shown in dotted yellow line.</p>
<p><a href="https://i.stack.imgur.com/uxVun.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uxVun.jpg" alt="Connect grounds" /></a></p>
