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so my idea is to create a circuit that when the piezoeletric is pushed, like a switch, but i wanted to make a variable so i can control how much force it needs to acionate the transistorPCB out of paint so when something come in the piezo and knocks it it send a signal to the arduino

sorry my bad drawing, i just need to know the values and if this is wright

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    \$\begingroup\$ I’m voting to close this horribly stated question because it has been abandoned for years without the asker making any effort to clarify the problem or fix the numerous typos. \$\endgroup\$ Oct 20 '20 at 2:09
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If you are pushing or tapping a piezo element, that is a voltage generator. At extremely low currents it can make several volts. This might be enough to turn on a small MOSFET like a 2N7000 or 2N7002. The transistor drain can then drive an Arduino input pin.

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  • \$\begingroup\$ it would be like 3v on the piezo that would generate... just for you to get the idea of the project... the piezo if knocked by a second i wanted to make that that voltage opens the gate of the transistor that is going 5 v from the bat... so the out pin of the transistor is the switch ir will work? like you said here? because it cant go any more than 2 v on the out of the arduino \$\endgroup\$ Aug 23 '17 at 0:13
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The simplified circuit is:

enter image description here

V1 is piezo and output signal is on collector of Q1.

However, if you want to hold the pin on arduino high for a time, you need to add the capacitance to the gate or somewhere else. Or do it by software.

Edit:

A version with stay high for a time can be modified to this:

enter image description here

It will extend the 1ms pulse from piezo to 200ms. For different timing change the C1. D2 is gate protecting zener diode.

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