I've just got back to thinking how to drive piezo sounder, and was wondering if something like the Natsemi LM4908 headphone amp working in bridge mode would be ok. The piezo has a 18nF capacitance The lm4908 seems a lot easier and smaller than brewing my own
Any potential gotcha's?
martin
Martin Griffith wrote in news: snipped-for-privacy@4ax.com:
Can you pass on the spec sheet for your piezo buzzer?? Many of these have on-board stuff that works just fine with a TTL signal.
-- Scott Reverse name to reply
It's this, the kpe130
I'm just trying to make it a bit louder with a push pull drive
martin
If you want louder, put an inductor across it ( 10-100mH - yes milli, not micro) and drive it with an open-collector transistor at the sounder's resonant peak. Use a HV transistor (e.g. MPSA42) if there is any risk of the piezo getting disconnected as it will swing over 100V off-load.
Bourns do some nice cheap axial inductors that work a treat.
micro) and drive it with
transistor (e.g. MPSA42) if
off-load.
Great, thanks for that tip, I have a go when I put the scope back together, (fuzzy focus)
martin
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