AVR-Chat

On May 25, 2005, at 8:58 PM, Ralph Hilton wrote:

> On Thu, 26 May 2005 11:49:45 +1000 you wrote:
>
>
>> Ralph Hilton wrote:
>>
>>>>> Connect it between 2 output pins and switch them alternately.  
>>>>> That effectively
>>>>> doubles the voltage.
>>>>>
>>>>
>>>> How does that work?
>>>>
>>>
>>> If the 2 pins are alternately pulled up then the peak to peak  
>>> voltage is 10.
>>>
>>
>> Not unless you "store" the voltage somehow. ie. you may need some
>> diodes and capacitors. At any one time the voltage measured across  
>> the
>> two pins is always no more than Vcc.
>>
>> Do you do advertisements for amplifiers?
>>
>
> Using pins 1 & 2:
>
> Pin 1 = 0, pin2 = 5v
> then
> Pin 1 = 5v, pin2 = 0
>
> Relative to pin1, pin2 goes from +5 volt to - 5 volt which is 10  
> volts peak to
> peak.

This technique was used in car stereo amplifiers before internal  
power inverters became commonplace.  If you connect an oscilloscope  
(with differential inputs) across the buzzer, it will appear to a 10  
volt peak-to-peak waveform even though only 5 volts is applied in  
each half-cycle.

Mike