I have been trying to understand the theory of why my
buzzer is not working as it is suppose to be*at least
to my understanding*.

I managed to salvage a buzzer from a PC. It looks some
thing like this.

http://www.rdiusa.com/products/Audio/DMT-12%20Srs.html

On the component it does not state the manufacturer so
I was left to identify the type of buzzer. Magnetic or
piezo. I applied the buzzer leads across the PIC i/o
pins PORTA 0 and ground. I checked the current
consumption during Q and it was draining about 32mA.
That was when I concluded that it was a magnetic
buzzer like the link above due to the coil. 


I measured the resistance of the buzzer which was 15
ohms. Now I pulse my i/o pin and there was no audible
sound. When I place a resistor in series with the
buzzer I can  hear an audible sound from the buzzer.
Now comes the question. Why do I need a resistor in
series? It is due to the time constant of the coil
that I need to reduce it?  t = L/R? Currently it does
not make sense here.

Can anyone help me understand the theory behind this?

Thanks,
John


 
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