In article
,
DaveC wrote:

http://imgur.com/Trvs5mk

This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the
piezos pads and... nothing.

An inverter (from the CD4069) is connected across the piezo. Guess I dont
understand anything about driving piezos.

Is this a standard practice?
Cheers.

Piezo drivers have a high impedance so they need high voltages. One
side of that piezo element is driven with the signal source and the
other side is driven with the inverted signal. That doubles the drive
voltage so it's loud enough to hear.

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