ADC has a 5V reference, then you will only get to use
about 1/5th of your total resolution to describe the signal.
But, if you could amplify that signal to a higher voltage,
then you will get much better resolution of that signal.
This means you can use more numbers to represent the
signal if the signal is larger. The way to get this amplified
signal is by using an op-amp. The one that works best — in
my opinion — for hobbyists is the LM324. The LM324
requires only one voltage supply; many op-amps require a
positive and negative supply. Figure 4 details how you
would use the LM324 to scale a voltage up for your
microcontroller. The gain of an op-amp is determined by the
bias resistors using this formula:
Vout = Vin(1+(Ra/Rb))
You can use a variable resistor in series with Ra to
tweak your amplifier to get the value that is just right. SV
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