At 17:18 1998-01-26 -0500, you wrote:
>>>Maybe a cheap vibrator can me made with a coil and a permanent magnet: The
>>>magnet monted on a spring plate so it swings without friction and noise,
>>>and driving the coil with resonant frequency? *very* cheap at high volume,
>>>but time, consuming to build in small production?
>>
>>Yes, this sounds like it might work, but I'm not looking to design the
>>thing. Does anyone know of sources for such?
>>
>>C. Webb
>
>
>The description fits the Star Micronics buzzers, series YMB et al. But they
>draw dozens of mils, too much to drive with a PIC output directly.
>
>Reg Neale
>
Yes, some kind of power stage must be needed in any case. There are a lot
to choose from. To optimize the drive for most output to least input power,
an H-bridge drive is the best. (When one end of the winding is to + the
other is to - ,and the shifting) To reduce a lot of power, but only a
little output, insert pauses in the shift: ++0--0++0-- and so on.
/Morgan O.