Voltage regulator heating up

[stendec]

Hello.

I'm building my first Arduino project. Its a project with small stepper motor from Adafruit. When I did programing, I power up the board from USB and everything was ok. But when I power the board with external adapter (9v 1A), power regulator starts heating up, I mean really hot, like its impossible to hold a finger to it. And heat-up occurs only when a motor is connected to board, when I unplug stepper, regulator is warm, but not hot.

Is it something with wiring or motor? any suggestions?

[adafruit_support_bill]

Powering from the USB bypasses the Arduino regulator and takes power directly from your USB port. Powering with 9v DC directs the power through the Arduino regulator which needs to burn off the excess 4v as heat.

Powering high current devices like motors from the 5v pin on the Arduino is not a good idea. Which motor are you using?

[adafruit_support_mike]

It sounds like you have the L293D/motor power connected to the Arduino's 5v pin. Try moving that connection over to the Vin pin.

Motors use a lot of current, and any current reaching the 5v pin has to lose its excess voltage through the regulator. That will indeed make the regulator hot.

The motor doesn't need regulated voltage though. Taking power for that part of the circuit from Vin, which connects to the DC barrel jack ahead of the 5v regulator, will allow most of the current to bypass the Arduino's regulator. Only the microcontroller and its support hardware will use power from the regulator, and those consume so little power that the regulator won't need to heat up.

Depending on the amount of current your motor uses, you might end up needing a second power supply. That's the easiest and most reliable way to keep things isolated.

[stendec]

Hi, thank you for replay.

Motor is 28byj-48, and driver chip L293DNE

I connected motor directly to Vin, and that resolve heating on power regulator, but! when the motor is activate even just for a second, after that its starts to heat up. Heating occurs only after the moment when motor is first time activated. Is it perhaps by badly written sketch?

[adafruit_support_bill]

Motor is 28byj-48

That is a 5v stepper. Running it at 9v from the VIN will make it overheat. You need a 5v supply for it. If you don't want to use a completely separate 5v supply, you can use a DC/DC converter to efficiently step the 9v down to 5v for your motor.

https://www.adafruit.com/products/1385