Hi all. I am using this circuit (not mine) to amplify the signal output by this piezo element. The circuit works fine for my purposes, but I've been using it to learn some basic electronics and had a few questions. Not pictured is the 5v power supply, and the 100uF capacitor between the positive and negative outputs of it.
1) R1 and R5 are in a configuration that I recognize as a voltage divider, but R5 is so big compared to R1 that it looks like there will effectively be no change in voltage. I assume it's either not what I think, or it's serving a different function in this case. What is the purpose of these resistors in this configuration?
2) If I understand correctly, the piezo outputs AC, but when I hook the output of the second op-amp up to an oscilloscope, I only see pulses in one direction. Although this is what I want, I'm confused about how this transformation is happening.
3) What purpose does the 100uF cap bridging the power supply inputs serve. What about the .1uF cap before the second op-amp?
I apologize for linking to the image. For some reason flash crashes every time I try to upload a file here. Thanks for your help!
1) R1 and R5 are in a configuration that I recognize as a voltage divider, but R5 is so big compared to R1 that it looks like there will effectively be no change in voltage. I assume it's either not what I think, or it's serving a different function in this case. What is the purpose of these resistors in this configuration?
2) If I understand correctly, the piezo outputs AC, but when I hook the output of the second op-amp up to an oscilloscope, I only see pulses in one direction. Although this is what I want, I'm confused about how this transformation is happening.
3) What purpose does the 100uF cap bridging the power supply inputs serve. What about the .1uF cap before the second op-amp?
I apologize for linking to the image. For some reason flash crashes every time I try to upload a file here. Thanks for your help!