I want to use the K2572 pre-amp to amplify a weak signal from a piezo sensor. I will use the sensor to make a contact microphone. The kind of piezo sensor that I want to use is shown in this link:
digikey.com/product-detail/e … -ND/412386
This will be a mono sensor, so I only need to use half (left or right) of the inputs/outputs of the stereo pre-amp.
I am confused about the usage of ground for the input and output of the K2572 pre-amp, and I am hoping that you can help explain so I can understand.
Question 1: If I use the left channel, I am guessing that the red lead from the piezo sensor attaches to connection 4 indicated in the assembly instructions. Do I then connect the black lead of the sensor to connection 3 (“ground”)? Note that the sensor is does not have a shielded connection. I have a 2 wire shielded cable wire. If I try to connect the sensor to a shielded cable to reduce noise on the way to the pre-amp, should the negative lead be connected to the ground sheath of the cable? Or should I connect the red and black leads to the two internal wires and separately connect the grounding sheath to the body of the metal box (an Altoid mint tin box - instructables.com/id/Make-a- … TEPS#step3
Question 2: To make the pre-amp very compact, I want to use two 9V batteries in series (18V) to power the pre-amp. Do I then connect the positive lead from the batteries to connection 6, and the negative lead from the batteries to connection 5? Will the preamp still work (with reduced gain) if I only use one 9V battery? The specifications indicate that 10-30V power supply is needed. I did not plan to use a coax cable to input the voltage.
Question 3: For the output, the assembly instructions say that I use connection 2. Does connection 1 then go to the shield of the coax cable that I am using to send the amplified signal to my oscilloscope via a BNC connector?
My goal is to make the very weak signal from the piezo sensor amplified and with improved impedance for analysis by the oscilloscope. I want to analyze the signal via FFT to understand how the sound of trumpets varies with different notes for a science fair project.
Note that I probably could have use the mono pre-amp (K1803) instead of the K2572, but it was not available in my hobby store and I wanted to get working on my project right away. I also noticed that the K1803 shows positive and negative power supply inputs.
Many thanks in advance for your help and advice!