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I have the circuit below, and I am wondering how the resistors and capacitor alter / determine the frequency that the piezo element vibrates at. I am assuming that they make a difference but I can't find any information pointing me in the right direction.

schematic

simulate this circuit – Schematic created using CircuitLab

Note that the values currently there were given and no explanation as to why they are so. Any guidance as to what controls the frequency of the oscillation would be greatly appreciated!

EDIT
That datasheet / catalogue for the piezo can be found here.
Additionally, the product page with more specifics is here.

I don't know what properties play a part in this calculation so any guidance in this would also be appreciated.

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  • \$\begingroup\$ Here's a starting point: electro-tech-online.com/attachments/… \$\endgroup\$
    – Andy aka
    Commented Jun 15, 2017 at 13:15
  • \$\begingroup\$ @Andyaka Well it certainly knowing that is called a CMOS oscillator! But would the case of R2 << R1 be valid in this case as it's only just under half? Also, does the feedback of the piezo not play a part in it at all? \$\endgroup\$
    – MrPhooky
    Commented Jun 15, 2017 at 13:19
  • \$\begingroup\$ I just fed you a starting point. Without a data sheet for the three terminal device you have in your picture it's guesswork. \$\endgroup\$
    – Andy aka
    Commented Jun 15, 2017 at 14:58
  • \$\begingroup\$ @Andyaka I have added datasheet and links to the question. \$\endgroup\$
    – MrPhooky
    Commented Jun 15, 2017 at 15:14
  • \$\begingroup\$ Not much to go on realistically - not enough information to model in a sim I'd say. \$\endgroup\$
    – Andy aka
    Commented Jun 15, 2017 at 17:14

1 Answer 1

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This type of piezo devices are made for building sounders with minimum extra parts. They have appeared about 45 years ago when one transistor and a couple of resistors were the maximal affordable extra parts. The frequency is determined by the mechanical resonance of the piezo element, it can be forced off very little from that frequency by adding more parts, say a capacitor.

No possiblities to estimate the frequency of your circuit without a reasonably accurate math model of the piezo part, if you need something more fine than piezo manufacturer's statement 2kHz with 0,5kHz tolerance.

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