May 14. Inverting Voltage Amplifier

Today  we build an inverting voltage amplifier using an op-amp.  We first calculate the theoretical voltage gain and the phase shift.

Pre-lab
Here we are given the circuit diagram, and used the node to get the relationship between  the Vin and Vout.

theoretical angular frequency, gain and phase angle will be at different frequencies.

the resistance and capacitance of elements are listed on the graph.The built circuit consists of 2 Resistors (10kOhm), 1 Capacitor (1 microF), 1 Op Amp (OP 27)

100Hz, the waveform for Vin(red), and Vout(blue).

 1000Hz, the waveform for Vin(red), and Vout(blue).

5000Hz, the waveform for Vin(red), and Vout(blue)

circuit

post lab calculations
we can see the percentage difference for gain and angle shift are both very small. This experiment is well performed.


Part 2
everycircuit simulating

Prelab calculations.
my last 3 digit is 155, so the resistance need to have f=155 is 29428 ohms.
in order to have this value, we use 2 10K resistor connect in series with a 10K potentialmter.

For the first time, We got the Graphics is not very ideal which is not a perfect square waveform. 

After we reconnect the wires, we get what we want the perfect square waveform. and we can adjust the resistance to change the frequency. Wow

Summary:

Today we go over how OP Amps work in AC circuit, and do labs to see how to see how they can apply in real life. 

For part 2, We learn how op amp relaxation oscillator works and how we can make our desired frequency. 

The main source of error may due to the inaccurate measure of period ( time) from the graph on screen.