Hi all,
I was learning the circuit design before implementing to Arduino. I browsed widely in textbook and journey paper, but here is some circuit design I can't understand. It is either filter or amplifier. Is anyone know the function/purpose of this circuit?
The OPAMP is LM358 and FG is the voltage source.
With one input of the opamp grounded, it looks like a transimpedance amplifier. (Current to voltage converter.) But the 500M resistor between the inputs seems a bit odd.
Agree with Transimpedance amplifier but same confused about the 500M resistor.
It could be worse. Circuit diagrams on the instructables website are usually completely wrong and sometimes burn-your-house-down dangerous.
Very obviously(*) its an integrator - opamp with capacitor feedback. R2 is to stop long-term drift. R1 may be to deal more gracefully with recovery from output saturation perhaps.
The equation for a capacitor is dV/dt = I/C, so V is proportional to the integral of input current in this circuit.
(*) obvious if you learn the common and basic opamp circuits.
I am guessing that R1 is added for Impedance matching but not sure though.
It looks like an amplifier for a dynamic microphone which would supply a differential output at 600 ohms or thereabouts.
Good Luck & Have Fun!
Gil
Whether the circuit makes sense depends on the nature of FG.
"Voltage source" is not helpful, and does not make sense.
It will be some sort of current source, since its a virtual ground.
