I am currently involved in an academic project which the topic is to design a Digital Tuner for Electric Guitars. My knowledge of electronic is very basic, so here I am.
I need to pre-process the signal that goes out from the pickups of a common electric guitar, let's consider passive pickups so....we have an output voltage from 200mV up to 1V of peak, with also negative peaks (of the same magnitude).
I have to use the STM32F4 (Discovery Board), so I need a very simple circuit that drives the On-Board 12-bit ADC, that takes, as inputs, signals with voltage between 0 and 3.3V. So I have to design a pre-amp circuit that amplifies and clamps the guitar's output.
I want to underline that I have never realized an electronic circuit (a real one, not in the simulator) before. I am wondering about:
- STM32F4 provides some voltage sources (5v or 3v). Shall I use these sources or is it preferable to go with an external voltage source (e.g., batteries)?
- I have chosen an opamp that is not, let's say, "handy" because it needs 2 voltage sources: the TL082. What op-amp do you suggest me to use? (maybe with only 1 voltage source)
- I have tried to design a circuit by using LTSpice, but I don't know if it is correct at all. You can also notice that I have inserted a filtering stage (LP w/ cutoff freq. 2,2 KHz) and a "protection" Schottky diode before entering in the pin of the board.