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I am currently working on a project in which I am using piezoelectric material to charge a battery. The voltage output of the piezoelectric material is variable depending on how much mechanical energy is applied to it. I don't want there to be too much voltage or it will fry the battery, and if there is too little, the battery won't charge well. I am using a 9V battery. How can I limit the voltage input to not be too high or too low?

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  • \$\begingroup\$ simplistic suggestion: how about a zener regulator? it's just a zener diode to clamp the voltage, and a resistor to limit the current once the zener starts conducting. \$\endgroup\$ – Matthew Di Nardo Sep 12 '18 at 16:48
  • \$\begingroup\$ How much voltage and current are you realistically expecting to get from this piezoelectric material? \$\endgroup\$ – Finbarr Sep 12 '18 at 16:52
  • \$\begingroup\$ The piezos I have come across so far usually are quite high impedance. Without a proper harvesting circuit I doubt you will get anything usable into a battery if you just connect it with some voltage protection. \$\endgroup\$ – Arsenal Sep 12 '18 at 16:59
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You can try using a buck boost converter circuit. I am posting this schematic only as an example. This IC can take only 5.5V as input voltage, so use this just to get an idea.enter image description here

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  • \$\begingroup\$ And a piezoelectric source will drive that without any problem, will it? \$\endgroup\$ – Finbarr Sep 13 '18 at 8:53
  • \$\begingroup\$ More mechanical energy gives an high voltage right? So if it exceeds the 5.5V it will damage the chip. \$\endgroup\$ – Arosha Dissanayake Sep 13 '18 at 8:56

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