Buzzer operation using NPN transistor

Hi All,


I want to switch ON a LED and a Buzzer by using transistor. Both are connected to a single NPN transistor 2N2222.


Input to the base of transistor is coming through a comparator. Is this is the right way?


Also, can I use Piezo buzzer for my application? There’s no frequency generation in my application.


Please see the attached picture for your reference.


Thanks!

hi alok,
You could use a acoustic sounder/bleeper instead of a piezo.
The sounder will work directly from 12v
E

Your LED current will be about 33mA. Isn't that excessive?

Can I drive the LED and Piezo buzzer, if connected in parallel?

hi,
The piezo will need to be driven by a square wave signal in order for it its to generate sound, say approx 3kHz.
Look at the 555 IC device.
E

A piezo beeper (sounder?) has an oscillator inside it. It is powered from 3VDC to 24VDC. Its current is only about 10mA when it has a 12VDC supply so it can be parallel to the LED and its resistor. The diode is needed only for a "magnetic" buzzer, not for a piezo beeper.

In case it is not clear from the posts so far, there are two types of piezo beepers. One is a bare piezo element and needs an oscillator circuit. The other has the oscillator circuit built in, and can be connected directly to a DC power source. Unfortunately, both can be packaged in the same round case, so there is no obvious difference to tell them apart. Do you know the manufacturer and part number of the piezo device you are using? Can you post a link to its datasheet?

ak