Ihave an arduino uno board and have a project i have been working on. i connected and LCD diplay, an ultrasonic sensor, two servos, a few switches and a couple of LED
s. i connected them all and programmed my board and i saw only my servos werent moving. So i connected a 12V 1.5A DC external source to my board and after a while i couldn`t find my board on my pc through my usb cable. Although my code still works, except for the servos, on my board. Did i blow something up??? Should i get a new board? i have checked the regulator and it is working properly. Please advise...
Assuming you connected the 12v to the barrel jack it should not have caused a problem - provided the polarity was correct.
You should NOT be powering servos through the Arduino. They should have their own power supply with a common GND with the Arduino. The servos and the Arduino could both be powered from the 12v supply (with a suitable voltage reduction for the servos.
If the servos are drawing too much current through it they will cause the Arduino to malfunction and may damage it.
If you are lucky the regulator did a thermal shut-down due to massive currents being drawn
Servos take 6V or so, power them independently from the Arduino with a 5, 6 or 7.2V supply
and common the grounds.
Use a supply that can handle the servos' current demands (budget at least 1A per servo).
The Arduino board cannot handle large currents, keep that current path completely external.