Adding external power supply to any arduino connected component

Question

I have an Arduino Pro Mini 3.3v and the voltage is too small for my buzzer to ring loudly. I want to add a 9v battery to power the buzzer.

This is my current circuit:
Arduino (pin 9) => Buzzer +ve
Arduino Gnd => Buzzer -ve

I want to power the buzzer using an external 9v battery but I have no idea how to implement it in the circuit. All I know is that the ground should be common.

What next?

Answer 1

You can use an NPN transistor for this purpose.

All you have to do is connect it this wayenter image description here

Obviously use a buzzer instead of the motor and pin 9 instead of 4 :D

Arduino (pin 9)==>1k-10k Resistance==>Transistor base

Buzzer +ve ==> + 9V

Buzzer -ve ==> Transistor collector

Transistor Emitter ==> battery -ve ==> Arduino GND.

So now whenever you set the pin 9 to HIGH the transistor would allow current to pass through it from collector to emitter and your buzzer would work just as you wanted.

• YaddyVirus: Sounds good... I was thinking of doing something similar!
• Manav: Thnx :D you can upvote if this helped you :)

Answer 2

Use a MOSFET. They are like little electronic switches. They will work fine with the 9V that you want to use.

Tutorial.

• Gerben: In this case a regular transistor will also work fine. Use an NPN transistor. The connect the 9V to +ve of the buzzer; -ve of the buzzer to the Collector of the transistor. - of the battery to both GND and the Emitter of the transistor. Connect the Base of the transistor via a resistor (e.g. 1kOhm) to an Arduino pin.
• Dat Ha: I find a MOSFET just simpler. They are more reliable for beginners.