ENGR337 Lab 2 2020 Spring
Lab 2 More Spice and the Compensation Probe
Name: Jesse Duran
Email: Duranijesse@gmail.com

1. Title More Spice and the Compensation Probe
2. Introduction
    During this lab we were tasked with building low pass filters and testing them in the lab using a function generator and an occsilloscope. The circuits were compared to LTSpice simulations and hand calculations.

3. Materials and Methods
 

Materials

Oscilloscope

Function generator

100k ohm resistor

1k ohm resistor

100p capacitor

680p capacitor

Bread board

Students followed instructions layed out on Yilectronics.com for tasks 1-3.

4. Results:

Task1

 Task 1.1

   
    Figure 1. Vout doesn't reach the voltage of Vin due to limited bandwith of the circuit.
   
 Task 1.2

   
    Figure 1.2a. Vout does not reach full voltage of Vin. Changing from 2v to 5v did not increase the bandwidth of the circuit.
   
   
    Figure 1.2b. Vout now reaches the full voltage of Vin. This is due to the reduced frequency allowing the bandwidth to have time to reach full voltage.
   
   
    Figure 1.2c. Vout reaches full voltage of 5v. Reducing the cap to 10p allowed for full saturation.

   
    Figure 1.2d. The capacitor reaches full charge due to reducing the resistor to 100ohm.


Task 1.3
   
    Figure 1.3. Time delay mesured on oscilloscope from real circuit. Square wave provided by function generator. (could have shortened time scale to get more accurate td.)
  
Task 2

   
    Figure 2. Simulated circuit of Vin vs Vout using LTSpice

   
    Figure 2b Calulation of Timedelay and attenuation
   
   
    Figure 2c. Oscilloscope measurement of time delay.

	Simulated	Calculated	Measured
Vin/Vout	.2537	0.2289	.24
Time Delay	20.5 μs	21.3 μs	21.2

Table 1. Comparison of simulated, Calculated and Measured values of Vin/Vout and Time delay.
    
   
    Figure 2d. Physical circuit

Task 3

   
    Figure 3.1 Compensation probe simulation with 9Meg ohm resistor.
   
   
      Figure 3.1b. Calulation for R to make 10x attenuation
   
   
    Figure 3.2 Compensation probe simulation with calulated capacitor added in. 10x attenuation was nearly achieved.
    
   
    Figure 3.2b Calculation for unknown capacitor value

5. Discussion
   
    During this lab students learned how to manuipulate capacitor and resistor values to make low pass filters. Additonally they became more familar with the compensation probe used for the oscilliscope.

3.3
     The type of scoped used was a 10x. Changing it to 1:1 reduces the input voltage read to be equal to the output probe, it is no longer amplified.