Re: How this circuit works?

John Fields wrote:

> The 155kHz signal from the oscillator is being rectified and smoothed,
> and then if the resultant DC rises to Vcc/2, the output of the second
> comparator will go high and supply DC to the piezo buzzer, which has a
> built in oscillator used to drive the piezo transducer.
> 
> 
> JF

I reckon at a pinch a couple of 555's or a 556 could be used to do the
same !

-- 
Best Regards:
                     Baron.