user58443: I have an arduino uno which turns on a water pump (12V, 3.6W) once every 10 hours for a few minutes (I've followed this tutorial on how to connect the water pump). To turn on the water pump I used a PN2222A transistor, and connected the base in serial with a 220 ohm resistor to the digital pin 9.
A few minutes after turning on the power on my Arduino UNO the PN2222A transistor burned out (lots of smoke coming out of it).
I also used a 1N4007 diode, cathode connected to the positive pin, and anode to the negative pin of the water pump.
The power supply outputs around 12.6V
Maybe the resistor is too low/weak?
I've created a schematic here, attached it's a snapshot of it.

EDIT1:
Here is a picture on how I connected my transistor. I've removed from the photo:

the input wires (should be top-right of breadboard)
wire to arduino digital pin (should be on h-19 on the breadboard)
water pump from the breadboard (positive pin: c-2, negative pin: h-2)


EDIT2 (a solution that worked for me):
It looks like the input to the arduino (arduino and the pump share the same 12V input, but the arduino's goes through a step down converter to 10V) was a bit loose (to be more specific, the negative pin was loose) and randomly, the arduino would shut down and then the pump would start (maybe because the digital pin becomes HIGH, dont know why though) all while the arduino is shut off. That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested and looks like when the same problem with the power happens, nothing is burning out :)

user58443: It looks like the input to the arduino (arduino and the pump share the same 12V input, but the arduino's goes through a step down converter to 10V) was a bit loose (to be more specific, the negative pin was loose) and randomly, the arduino would shut down and then the pump would start (maybe because the digital pin becomes HIGH, dont know why though) all while the arduino is shut off.
That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested in one of the comments and looks like everything is ifne now (even when the same problem/bug with the power randomly happens)

user58444: Seems to be a simple pinout issue, I checked the PN2222A and its pins are in EBC order. You probabily reversed it and burned the transistor. Reverse the transistor and the problem will be solved.

simulate this circuit – Schematic created using CircuitLab

user15146: TinkerCAD may have mislead you on the pinout for the transistor
TinkerCAD

PN2222A


user58444: By this, does it mean that you still have a problem turning the pump on? Because a PN2222A should handle up to 1A through its collector, as the datasheet states http://www.mouser.com/ds/2/149/PN2222A-371983.pdf

That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested and looks like when the same problem with the power happens, nothing is burning out :)

If you are still having problem turning the pump on, try turning it on manually by moving the jumper that is on the Arduino pin 9 to either GND or 5V, that should indicate if the problem lies on the Arduino pin (GPIO) or on the transistor.
It is also important to check the current needed by the pump, because the datasheet indicates that, to have a current IC = 350 mA -> IB = 35 mA which is close to the maximum of an Arduino pin (40 mA). If the Arduino pin cannot supply enough current to put the transistor in saturation mode, it will either kill the pin or put the transistor in its linear region, meaning it will dissipate a lot of power (Ic*Vce).

Base-Emitter Saturation Voltage
IC = 150 mA, IB = 15 mA
IC = 500 mA, IB = 50 mA


58443: <p>I have an arduino uno which turns on a water pump (12V, 3.6W) once every 10 hours for a few minutes (I've followed <a href="https://www.instructables.com/id/Automatically-water-your-small-indoor-plant-using-/" rel="nofollow noreferrer">this</a> tutorial on how to connect the water pump). To turn on the water pump I used a <strong>PN2222A transistor</strong>, and connected the <strong>base</strong> in serial with a <strong>220 ohm</strong> resistor to the <strong>digital pin 9</strong>.
A few minutes after turning on the power on my Arduino UNO the <strong>PN2222A</strong> transistor burned out (lots of smoke coming out of it).</p>

<p>I also used a <strong>1N4007</strong> diode, cathode connected to the positive pin, and anode to the negative pin of the water pump.</p>

<p>The power supply outputs around 12.6V</p>

<p>Maybe the resistor is too low/weak?</p>

<p>I've created a schematic <a href="https://www.tinkercad.com/things/93WNCASSUjE" rel="nofollow noreferrer">here</a>, attached it's a snapshot of it.</p>

<p><a href="https://i.stack.imgur.com/lzeB8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lzeB8.png" alt="tinkercad schematic"></a></p>

<p><strong>EDIT1:</strong>
Here is a picture on how I connected my transistor. I've removed from the photo:</p>

<ul>
<li>the input wires (should be top-right of breadboard)</li>
<li>wire to arduino digital pin (should be on h-19 on the breadboard)</li>
<li>water pump from the breadboard (positive pin: c-2, negative pin: h-2)</li>
</ul>

<p><a href="https://i.stack.imgur.com/VSxU4.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VSxU4.jpg" alt="enter image description here"></a></p>

<p><strong>EDIT2 (a solution that worked for me):</strong></p>

<p>It looks like the input to the arduino (arduino and the pump share the same 12V input, but the arduino's goes through a step down converter to 10V) was a bit loose (to be more specific, the negative pin was loose) and randomly, the arduino would shut down and then the pump would start (maybe because the digital pin becomes HIGH, dont know why though) all while the arduino is shut off. That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested and looks like when the same problem with the power happens, nothing is burning out :)</p>
 58443: <p>It looks like the input to the arduino (arduino and the pump share the same 12V input, but the arduino's goes through a step down converter to 10V) was a bit loose (to be more specific, the negative pin was loose) and randomly, the arduino would shut down and then the pump would start (maybe because the digital pin becomes HIGH, dont know why though) all while the arduino is shut off.</p>

<p>That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested in one of the comments and looks like everything is ifne now (even when the same problem/bug with the power randomly happens)</p>
 58444: <p>Seems to be a simple pinout issue, I checked the PN2222A and its pins are in EBC order. You probabily reversed it and burned the transistor. Reverse the transistor and the problem will be solved.</p>



<p><img src="https://i.stack.imgur.com/bEAQJ.png" alt="schematic"></p>



<p><sup><a href="/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fbEAQJ.png">simulate this circuit</a> &ndash; Schematic created using <a href="https://www.circuitlab.com/" rel="nofollow">CircuitLab</a></sup></p>
 15146: <p>TinkerCAD may have mislead you on the pinout for the transistor</p>

<p><strong>TinkerCAD</strong></p>

<p><a href="https://i.stack.imgur.com/z6D3Z.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z6D3Z.jpg" alt="enter image description here"></a></p>

<p><strong>PN2222A</strong></p>

<p><a href="https://i.stack.imgur.com/y9RxJ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/y9RxJ.jpg" alt="enter image description here"></a></p>
 58444: <p>By this, does it mean that you still have a problem turning the pump on? Because a PN2222A should handle up to 1A through its collector, as the datasheet states <a href="http://www.mouser.com/ds/2/149/PN2222A-371983.pdf" rel="nofollow noreferrer">http://www.mouser.com/ds/2/149/PN2222A-371983.pdf</a></p>
<blockquote>
<p>That's when the transistor (PN2222A) burned out. I switched to TIP120 with a 1k resistor as @Jot suggested and looks like when the same problem with the power happens, nothing is burning out :)</p>
</blockquote>
<p>If you are still having problem turning the pump on, try turning it on manually by moving the jumper that is on the Arduino pin 9 to either GND or 5V, that should indicate if the problem lies on the Arduino pin (GPIO) or on the transistor.</p>
<p>It is also important to check the current needed by the pump, because the datasheet indicates that, to have a current IC = 350 mA -&gt; IB = 35 mA which is close to the maximum of an Arduino pin (40 mA). If the Arduino pin cannot supply enough current to put the transistor in saturation mode, it will either kill the pin or put the transistor in its linear region, meaning it will dissipate a lot of power (Ic*Vce).</p>
<blockquote>
<p>Base-Emitter Saturation Voltage</p>
<p>IC = 150 mA, IB = 15 mA</p>
<p>IC = 500 mA, IB = 50 mA</p>
</blockquote>
