Our experiment today was to build an Operational Amplifier that lets us amplify audio or other AC signals with a positive power supply. We didn't really figure out exactly how this is possible, but I do know that it somehow allows us to also amplify the negative half of the waveform. Here is the completed circuit. The potentiometer dictates the gain of the signal.
In the schematic we were told that for this circuit, V Out = Vin * (-R(f)/Rin). In this case, Rin = 2.2 kOhms, and R(f) ranges from 1 Ohm to 10 kOhm. If we talk about gain in decibels and use the ratio of V Out and Vin, then the maximum gain would be 20log(-2.2kOhms/1Ohm) or 66 decibels, and the minimum gain would be 20log(-2.2kOhms/10kOhms) or -13 decibels. (Something seems off here, the calculator wouldn't let me use a negative value for the R(f)).
Final Project
Here is a diagram of my user interface. It's going to be pretty simple, with just a few pads and knobs.
Here is a flowchart for my controller
Materials List
2 Bowls, preferably wooden ($10)
Drum Pad surface, probably just colored tape. ($5)
Box, with some way to suspend bowls, might need to rig some crazy rubber band deal. ($10?)
4 Piezo Diaphragms ($15)
3 555 Timers (If I use these for noise) ($5)
3 LM58 Op Amps ($10)
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