hi ardunio users
when first i brought arduino uno,for try i attached micro servo to it.and when i was coding it i touched it voltage regulator was TOO HOT :o and the on light was dim .then i removed the servo and tred to attach to usb so it was not get hot.
so i got to know that when we attach servo then only it gets hot.

so can you please help me.

You don't say which servo or how it's connected, but the Arduino Uno can only supply a limited amount of current through the on-board regulator.

Google the specs:
"3.3V: 3.3V supply generated by on-board voltage regulator. Maximum current draw is 50mA."

Further, if you are trying to power it through a GPIO pin, you are limited to 40mA.

Also, since you didn't say how you are powering the Uno, but if you are using a 12V wall-wart through the barrel connector, then the on-board regulator has to dissipate everything above 5V as heat.

The best advice is NEVER try to power servos or motors direct from the Arduino. They all use a lot of power. ALWAYS use a separate power source e.g. 4 x rechargeable AA batteries.


The OP Reported post #2 saying

i am powering with 9v. and iused usb to upplode that time the regulator was hot

I assume that it was meant as a comment

it got hot when i connected with usb to laptop

it got hot when i connected with usb to laptop

I do not see how the regulator on an Arduino Uno board, just as an example, can get hot when the board is USB powered? This is what it looks like:

The regulator is only used when external power is applied using the pictured connector.


A very real danger is that the obsolete tutorials on the Arduino site and others misleadingly imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator allow a usable source of 5 V power. This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the very beginning of the Arduino project when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.

If you are asking this question, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.

This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the (older) Arduinos, it does not.

Powering via the "barrel jack" or "Vin" connections is asking for trouble. The "5V" pin is not by any means an output pin, if anything a "reference" pin but most certainly the preferred pin to which to supply a regulated 5 V.
Stock answer

Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

What model Arduino controller are you using?
What micro servo?

Thanks.. Tom.... :slight_smile: