3/31 :Summing Amplifier, Difference Amplifier

 Summing Amplifier & Difference Amplifier

 In this lab, we used an op amp to sum two input voltages.
Practice problem on solving op amp circuits before Lab:  We leaned how to used node to calculate the V0, V2, and Vs.

Buffer Amplifiers, which doesn’t have much change in voltage when there is a big change in output voltage, therefore Vin = Vout.Inverting Amplifier, which produces an output with opposite sign, Vout = -Rf/Ri * Vi. 

Pre-lab for Summing Amplifier : we used the Vout = - R3/R1 * (Va+Vb) to get the R3 should less than 600ohm.  

This is the result table of our data, with Va varying from -4V to +5V, and Va keeps constant at +1V. We do fine on this lab. 

To build the circuit, we used two 1k resistors, one 220  resistor, one OP 27, one Analog Discovery device to provide the two input voltages, and a multimeter to measure the output voltage:

Difference Amplifier: How to used node to calculate the Va, Vb, and Vo.

Pre-lab for Difference Amplifier: We figure out that if we use four identical resistors, the out put voltage is simply Vout = Va - Vb.

This is the set up of this experiment.  We build the circuit with four 10k resistors, one Op Amp 27, an Analog Discovery device to provide +/-5V and two input voltage. 

This is the result table of our data, Va keeps constant at +1V. We do fine on this lab. We get a minimum % difference of 1% and a maximum of 3%,the results were very close to what we expected 

Summary: In this Lab we learn more about about different types of OP Amp and their distinct utilities, and did two labs demonstrating how OP Amps can be used to combine and subtract two input signals.

Lab 10 (03/26): Inverting Voltage Amplifier

 Inverting Voltage Amplifier

Class practice

Per-lab: We use R1=2.2K R2=4.4K.

We built following non ideal op amp circuit.  Measured vout values and compared it with v expected.


Mearsurment for the Vin and Vout

Graph of Vout vs Vin.

Lab 9 (3/24): Maximum Power Transfer

Maximum Power Transfer

Per-Lab: we do a pre-lab finding the power of a source when it is ideal and not ideal.

We  measured  the resistor for R1 and R2, and the voltage, then got the Rs for both.

The circuit set up for the experiment.

To find the R when Pmax,  it is differetial dP/DR, so we got Rth=RL.

So when we used R1=RL=2.2K Pmax=2.8mW


We measured the voltage which across the R.

Wo got the % different for the power.

Lab 8: Every Circuit & Thevenin's Therem

Teaching how to using Every Circui


How to use the Thevenin's Therem to solved for Rt and Vth. 

Using every circuit we solved for Rt and Vth. 

Pre-lab: we got Rth= 7.2K ohm, and Vth=0.4179V. compare with  EveryCircuit to see if we get the right answer.

useing the EQ to solute I=54.4uA

Meatured the Rth=7.10K

Meatured the V(4.7K)=0.17V


Meatured the V(1k)=0.54V

we got % different of V(1K) = 1.9%,  and % different of V(4.7K)=0%

Connect the potentiometer between the terminals a-b.

measurment for the load voltage as a function of potentiometer resitance.

We now can plot a graph for power vs. resistance. We can see that the power increases as the load resistance increases until it reaches a maximum and then starts to fall a bit. The maximum is 8.02 mW, which occurs when our load resistance is 5.24 kΩ. However, This does not corresponds closely to our Thevenin resistance of 7.20 kΩ. 

Lab 7: Time-varying Signals & A BJT curve Tracer

Time-varying Signals

Pre-Lab: a) sinusoidal wave.  b) triangular wave.  c) square wave The amplitude of the output would be half of the input. 

This is the set up of the experiment. 

This is input value. Amplitude is 2v.

This is the graph for the sine wave.  The frequency and period are its original value. The amplitude becomes half which is 1V. 

This is the graph for the square wave.  The frequency and period are its original value. The amplitude becomes half which is 1V. 




This is the graph for the triangular wave. The frequency and period are its original value. The amplitude becomes half which is 1V. 

LAB: A BJT curve Tracer

In this lab, we are going to investigate the collector current, IC vs. collector voltage, VCE characteristics of the BJT. We are going to use a breadboard, a 100K Ω Resistors, a 100 Ω Resistor, and a small signal NPN transistor.

Set up of BJT curve tracer circuit

 

Here are our first input wave (Channel 1) and second input wave (Channel 2).

Here is the oscilloscope of the wave it detected.

Quiz 2

We are asked to use mesh analysis to get the correct answers for the asked value .