Hi,
I need an opamp to amplify the signal from a piezoelectric transducer (piezoelectric disc - 35mm), and I noticed in your document “AN-31 Op Amp Circuit Collection” that you have a circuit for a piezoelectric transducer with an opamp that is now discontinued ( LM108 )… So I started looking for others, and I found INA125, TLC251, TL082, LMC660, LM335, OPA353 – which one would you recommend, or are there other better solutions?
Another doubt I have is that after pre-amplifying the piezo, it will be connected to a sound card (http://www.roland.com/products/en/UA-25/) having a maximum Nominal Input Level of +4 dBu. I’ve searched about how to convert dBu for mV, in order to know the maximum I can amplify with the opamp, and I realized that +4 dBu = 1,23V = 1230mV. My problem is that I don’t know the maximum mV of the sensor, so that I can calculate its gain. How could I solve this issue?
I have one last question… I gathered these data from the sensor: Resonant Frequency: 2.6KHz ±0.3KHz; Resonant Impedance: 250R; Capacitance: 400nF. Are they relevant for the opamp choice?
thanks,
Carlos Esteves