Thursday, May 14, 2015

AC op amps day 23

Today we started the class learning about AC circuits with op amps
 two important properties of an ideal op amp:
1. No current enters either of its input terminals.

2. The voltage across its input terminals is zero.

Following is AC circuit problem with op amp


LAB:  Inverting voltage ampliflier lab

Purpose of this lab is to see the amplitude gain and phase difference between the output and input signals of a inverting voltage amplifier circuit. Here is how we calculate gain and phase shift:

Following is our circuit set up


The circuit consists of 2 Resistors (10kOhm), 1 Capacitor (1 microF), 1 Op Amp (OP 27), and a Analog Discovery device to provide input and measure output:Based on the formula above, we can generate theoretical gain and phase shift values with three different input frequencies.


Following is graph of input of 100 HZ at 2V


Following is graph of input and output. input is in red and output is in blue



Following graph of input of 1Khz at 2V




Following graph of input and output at 1Khz



Following is the graph of input output at 10Khz at 2V


Calculation and % error was calculated and shown in previous picture.

 Op Amp Relaxation Oscillator Lab

In this lab we constructed a relaxation oscillator, which is a type of device that will act as a switch when a certain voltage is applied to one of its terminals. 

Following is the every circuit set up of the circuit


Following is the set up of our circuit on bread board.consists of 2 Resistors (3 kOhm), 1 POT, 1 OP 27, 1 Capacitor (0.1 microF), and an Analog Discovery device to provide input and measure output:

Following is the output graph of 733 Hz input at 2V



This voltage is usually the voltage across a capacitor that is being charged or discharged. 

Percent error was due to obtaining data. we might not have read the data correcly or exactly.

Summary: we learned about op amps in AC circuit and did 2 labs to see how it works. 

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