Add Fritzing circuit

Author: maxgerhardt

libraries/OPAMP/README.md

@@ -51,6 +51,8 @@ Connect A1 to 3.3V, the output should be 3.3V.
 
 For an amplifier circuit, see https://www.electronics-tutorials.ws/opamp/opamp_3.html. A simple 2x amplifier can be built by using e.g. two 10K resistors: Connect one resistor between "Minus" and GND. Then use the second resistor to connect the output and "Minus" together. Any signal input at the "Plus" will now appear with double the amplitude at the output pin. Of course, the input signal and the Arduino Uno R4 should share the same GND and the amplified output signal should not go above ~4.7V, otherwise clipping will appear.
 
-Below is a capture of an oscilloscope in which a circa 2V square-wave (green, channel 2) is amplified to 4V square-wave (yellow, channel 1) with the aforementioned circuit.
+Below is a capture of an oscilloscope in which a circa 2V square-wave (green, channel 2) is amplified to 4V square-wave (yellow, channel 1) with the aforementioned circuit. The input signal was generated by a function generator (and shared GND was connected).
 
-![amp](amp_screenshot.png)
+![amp](amp_screenshot.png)
+
+![amp_circuit](amp_circuit.png)