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piezo buzzer etc

Protecting circuit from piezoelectric disc voltage spike

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I have a piezoelectric disc, and I’m trying to use to build a primitive sonar. I connected the disc to an oscilloscope and if I press very hard on the disc, I see that the voltage can spike pretty high. I’m not sure how much current there is.

In an application with a piezoelectric device, should I use a voltage regulator on the output of the piezo, and would that protect my circuit on the other side? I want to connect it to an ATTiny85 without frying the chip.voltage-regulatorattinypiezoattiny85shareedit  follow  flag asked 3 hours agomj_28722 silver badges77 bronze badges

  • 4No, you wouldn’t use a voltage regulator you’d use a series current limiting resistor. – Andy aka 3 hours ago
  • 1If you want to transmit a SONAR pulse to get the piezo to ring strong, you want to have a HV transistor to drive it high then open and ring then clamp shut to 0V to discharge the energy fast (blanking) pulse then the Rx echos can be measured except for the tbd xxx ns or us delay time to stop transmitting the ringing pulse. So adding a series resistor makes that less sensitive for the transmission pulse. otherwise a step up pulse transformer can be attempted for Tx with a high side PNP current source then an NPN clamp clamp to gnd with a small deadtime using a half bridge BJT driver. – Tony Stewart Sunnyskyguy EE75 2 hours ago 
  • 1If you define your design specs in good detail and any component spec links, then a good answer is possible – Tony Stewart Sunnyskyguy EE75 2 hours ago 
  • @mj_, the usual quick and dirty trick is to use a zener diode. But I found that zener is not very effective. – tlfong01 58 mins ago   
  • You might like to read my measurement of piezo spike with and without the protective zener: “Piezo sensor to pick up acoustic instrument signal using Rpi and ADC Asked 1 year ago Active 1 year ago Viewed 569 times”: raspberrypi.stackexchange.com/questions/103868/…. Cheers. – tlfong01 37 mins ago   

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2 Answers

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Question

Protecting circuit from piezoelectric disc voltage spike


Answer

The voltage spike might be as high as 30V. You can use a zener to clamp the spike. See appendices for more details.


References

(1) tlfong01’s piezo experiment, Rpi SE 2019

(2) Piezo Pickup Transducer 27mm Contact Microphone Trigger – Discs Elements for Acoustic Instrument: Guitar, Drum, CBG etc. with Leads $6.99/12Pcs

(3) MCP3008 SPI 8 Channel 10 Bit ADC Datasheet – MicroChip


Appendices

Appendix A – Characteristics of piezo used in this experiment

Piezo Pickup Transducer 27mm Contact Microphone Trigger – Discs Elements for Acoustic Instrument: Guitar, Drum, CBG etc. with Leads $6.99/12Pcs

Resonant frequency: ***4.6 +/- 0.5 KHz***

Resonant impedance (ohms): ***300Ω max***

Plate material: Brass

For: Acoustic Instrument Pickups, Stomp Boxes, Contact Mics, etc...


Appendix B – Piezo toy schematic


piezo toy schematic

Appendix C – Voltage spike without Zener protection


zener protection

Appendix D – Detecting (Electromagnetic Buzzer) flyback voltage and current spike experiment


Detecting (Buzzer) flyback voltage and current spike experiment 1/2


Detecting (Buzzer) flyback voltage and current spike experiment 2/2


buzzer voltage spike

shareeditdeleteflagedited 3 mins agoanswered 29 mins agotlfong011,17411 gold badge44 silver badges77 bronze badges

  • 1Could you please, please try to post straightforward answers that simply make your point without all this division into less relevant appendicies and links? – Chris Stratton 3 mins ago 

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Please post a circuit when asking questions. A parallel resistor with a proper value is what you need. The current isn’t high. The first circuit is with Arduino. The second circuit is recommended.

You can check the circuits:

http://www.learningaboutelectronics.com/Articles/Piezo-knock-sensor-circuit.php http://www.robotoid.com/appnotes/sensors-piezo-disc-touch-bar.html https://www.homemade-circuits.com/simplest-piezo-driver-circuit-explained/ https://www.homemade-circuits.com/diy-contact-mic-circuit/shareedit  follow  flag answered 3 hours agoCFCBazar com44011 silver badge88 bronze badges

  • Parallel? No. Questions on Stack Exchange sites must have stand-alone value, they cannot rely on links for the entirety of any accurate content. – Chris Stratton 1 hour ago

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