On Oct 3, 2005, at 8:42 AM, Stephen R Phillips wrote:

>>     I am currently using a PIC to generate tones on
>> the speaker. It runs on 5Volts. The speaker produce a
>> tone which is too soft to hear after 5 meters away. Is
>> it possible to increase the volume of the speaker
>> using a 5Volts setup?
>
> Yes you would want to use a bridge setup to drive the speaker. Driving
> it with 5V gives you a 5Vpp signal or a 2.5V and a bit smaller RMS wise
> in a bridge configuration you have 10Vpp which is a much larger signal
> (and thus louder).   To do this however you need 2 PIC pins and 4
> transistors in a full bridge setup.

The original poster doesn't say what the hardware looks like now.  A
typical setup drives the speaker through a current limiting resistor
directly from an output pin, carefully staying within the 25mA that
a PIC pin is allowed to output.  Since "full volume" in an 8ohm speaker
requires well in excess of 25mA, you have a lot of room for improvement
without going to a full-bridge setup; a simple transistor will get you
a lot more volume...

BillW
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