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Am a hobbyist beginner with no prior electrical engineering knowledge (though can follow a basic circuit), so please bear that in mind when giving your valued advice! am following an instructable to build a piezoelectric circuit project.

The instructions say that the piezo elements generate AC and not DC so a bridge rectifier made of four diodes needs to be added, since the piezo elements will cancel each other's output if these diodes are not included.

6 piezo elements and 1 bridge rectifier is called for per piezo element to prevent this, however only one bridge rectifier is shown for 3 piezo elements in the instructions.

So far, I've followed the circuit below with 3 piezo elements and one bridge rectifier:

Circuit example from instructable with bridge rectifier shown

However, I'm aware that another 5 bridge rectifiers to be added (the other 3 piezo elements are underneath the white board I think). I'm looking for the following:

1) Can anyone describe the circuit diagram I should follow to include the additional 5 bridge rectifiers? here's the current circuit

enter image description here

I realize that each bridge rectifier should be connected on the silver wire connecting the piezos in the jpg, but then does that mean I need to connect all six wires from the rectifiers back to the - and + of the battery?

2) Can anyone describe/explain how to connect the circuit diagram with the rectifiers, capacitor + switch

3) An idea of what type of capacitor is best to use here (maybe a ceramic capacitor that can handle 100V, as it should be x3 the potential highest output which is around 27V? but may be incorrect)

Thanks for your help

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  • \$\begingroup\$ What is it you are actually trying to make? And does the instructable have a schematic? \$\endgroup\$ – uint128_t Mar 5 '16 at 16:55
  • \$\begingroup\$ Hi I am trying to build the project from here instructables.com/id/Electricity-Generating-Footwear/?ALLSTEPS. The schematic is the same as in the pictures (couldn't post the link before since it only allows you to post two links max on basic account) \$\endgroup\$ – uvolt Mar 5 '16 at 17:55
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Without reading through the Instructable I think what you want is this:

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. Multi-piezo rectification.

The piezo output will exhibit a very high internal resistance. Once they are loaded the output voltage will collapse. In practice the capacitor loads the piezo so that each piezo pulse will add a little charge to the capacitor. The max voltage the capacitor sees will depend on the rate of charge versus the rate of discharge.

schematic

simulate this circuit

Figure 2. Six-piezo rectification. All rectified outputs joined in parallel.

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  • \$\begingroup\$ Hi transistor, thanks for the schematic, however 6 piezo elements are required (the same circuit connected on the opposite side, the above shows the top side but not the bottom). How can I join these two circuits? Following the above diagram, would the opposite circuit be connected at points D3/D4, D1/D2 etc (obviously with diodes facing the correct way)? To clarify, there should be another piezo element under each one shown in the diagrams \$\endgroup\$ – uvolt Mar 7 '16 at 5:55
  • \$\begingroup\$ The other side of what of the white board? See Figure 2. \$\endgroup\$ – Transistor Mar 7 '16 at 7:35
  • \$\begingroup\$ Underneath the white board shown in the post there were more piezo elements. Thanks for the updated schematic. \$\endgroup\$ – uvolt Mar 11 '16 at 20:06

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