Troubleshooting weak alarm buzzer

Hi,

I have an alarm device with buzzer, it must be 65db loud, but it produces only very low sound.

I've checked the transistor and transformer driving the buzzer, and found they are good.

Is the problem definitely in the buzzer?

If yes, can it be repaired? or it must be replaced

Thanks for experience sharers

Do you mean:-

Its a fresh circuit assembled by you and you are not happy with your model?

Check the operational voltage range of the Buzzer. There are common Buzzers operate 3-27 volts.

Is it getting sufficient current and/or voltage?

Can you give the circuit diagram.

---------- Post added at 23:51 ---------- Previous post was at 23:39 ----------

The downside is of a buzzer is that it is relatively power hungry(good amount of current), in most cases requires more than 5v to drive to make a decent noise, but more importantly the crappy ones can produce a significant back-emf which can easily destroy a transistor if you don't put a suppression diode across them.

papunblg said:

Do you mean:-

Its a fresh circuit assembled by you and you are not happy with your model?

Click to expand...

-NO, It's a commercial product, not assembled by me. (made in china)

- This problem is found in some devices only.

Here is a photo of the buzzer:

Richman87 said:

It's a commercial product, not assembled by me.

This problem is found in some devices only.

Click to expand...

Could you retrieve buzzer's schematic from this commercial board? Is something written on this buzzer to lead us to the datasheet? What is the driving voltage of the buzzer?
Without some basic information, it's hard to assume what the problem could be.

alexxx said:

Could you retrieve buzzer's schematic from this commercial board? Is something written on this buzzer to lead us to the datasheet? What is the driving voltage of the buzzer?
Without some basic information, it's hard to assume what the problem could be.

Click to expand...

Agree with Mr. Alexxx.
Without those details its very hard to comment.
Off the record, I can say that the given picture looks more like a piezoelectric sound device without an oscillating electronic circuit. Maybe the oscillating circuit present on the circuit board. Without a proper oscillating circuit or any malfunction in this circuit the sound will be distorted / low.

alexxx said:

Is something written on this buzzer to lead us to the datasheet?

Click to expand...

No, there is nothing written on the buzzer.

By the way, I've gotten another device with good sound, then connected its buzzer to the malfunctioned device and it worked well, so the problem is definitely in the buzzer, the question now:
Is replacement the only fixation for this device? or I can do something with this weak buzzer.

---------- Post added at 20:18 ---------- Previous post was at 20:10 ----------

papunblg said:

Off the record, I can say that the given picture looks more like a piezoelectric sound device without an oscillating electronic circuit. Maybe the oscillating circuit present on the circuit board. Without a proper oscillating circuit or any malfunction in this circuit the sound will be distorted / low.

Click to expand...

Is "piezoelectric sound device" called "buzzer"?

papunblg said:

Maybe the oscillating circuit present on the circuit board.

Click to expand...

Exactly it is on the PCB..

Richman87 said:

By the way, I've gotten another device with good sound, then connected its buzzer to the malfunctioned device and it worked well, so the problem is definitely in the buzzer

Click to expand...

Maybe but not definitely. Still we don't know operating voltage and we'll never find out since no datasheet is available. You could measure operating voltage on both boards, or place the "problematic" buzzer on the other board, or at least observe the driving circuit on both boards. Moreover we don't have a datasheet neither from the second buzzer. I wouldn't jump to conclusions so easilly.
However, there is a chance that the problem could be a weak buzzer.

A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric. A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source.

A pizzoelectrict buzzer may or may not come with an oscillating circuit connected inside a black round housing like the following:-

It looks like the piezo in the photograph has corrosion on it. That would most certainly stop it making sound properly.

They are VERY cheap to buy and no, they are not reparable.

Brian.