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I want to measure the charge displaced by a force acting on a piezoelectric sensor. The problem is I don't know the sensor so I have no idea how big the current generated by the sensor may be nor what the sensor parameters are (leakage Resistance, parallel Capacitance of sensor).

Does anyone know if there are some pre-made solutions like an IC or something, that can measure the charge and produce an output signal? It does not matter if the output is analog or digital, all I want is a good measurement of my charge and then get an idea how big the applied force is.

I know this is usually done with a charge amplifier, but since I don't know much about the sensor, I would like a already made solution so I can make sure there are no errors in my circuit that influence my measurement.

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    \$\begingroup\$ So, you want a solution the works for any piezoelectric sensor? I would either build the charge amplifier myself and tweak the capacitor values in order to get a reasonable output, or buy 1 or 2 (spare) break out boards with an amplifier on it and tweak those. \$\endgroup\$ – Huisman Feb 20 '19 at 8:20
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    \$\begingroup\$ BTW, how would you relate the gained 'good measurement' to 'how big the applied force is' if you don't have any data of the sensor? Calibrating it with known weights? \$\endgroup\$ – Huisman Feb 20 '19 at 8:22
  • \$\begingroup\$ Pretty much calibrating and hoping for the best... My first goal is to get a running circuit and then work from there. And since I don't know much about the sensor I want a very good circuit so I can assume that the effects I measure are from the sensor and not my circuit \$\endgroup\$ – Robert Reichel Feb 20 '19 at 8:51
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    \$\begingroup\$ Put a 100,000 ohm resistor across the piezo. Hang a 10MegOhm scope probe on that, set to 10 volts/division and 1milliSecond/division. Start tapping the sensor. \$\endgroup\$ – analogsystemsrf Feb 20 '19 at 17:58
  • \$\begingroup\$ This also worked when I just connected the piezo to the oscilloscope with a 10MOhm probe. Can I now calculate the current with Umax/10MOhm ? \$\endgroup\$ – Robert Reichel Feb 25 '19 at 6:20
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The charge amplifiers I have used before with accelerometers were sold with the sensors. But there seems to be generic charge amplifier instruments on the market. E.g. this. If you don't want to build a circuit, you can characterize your sensor with an instrument, and build the circuit after you determined the parameters.

Otherwise, if there is no budget for an instrument, I think the only solution is to build something adjustable yourself.

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