ENGR337 Lab 2020 Spring
Lab 2
Name: Humberto Arredondo Perez
Email: harredondoperez@fortlewis.edu

1. Title:     More Spice and Compensated Probe

2. Introduction
In this lab we will do simulations in LT Spice to get more familiar with the software building a few circuits and understanding the mechanism of the compensated scope probes.

3. Materials and Methods

LT Spice	Resistors	Function Generator
Breadboard	KompoZer	Multimeter
Capacitors	Oscilloscope	FileZilla

First, for task 1.1. We built the circuit using symbols showing in Figure 1, used transient analysis to simulate the voltages at Vout and anylized the results. For task 1.2a on Figure 2, we changed the voltage to 2v, for 1.2b, we change V to be 5v, Ton and Tperiod to 1u and 2.1u separately, then on 1.2c, we reset everything to original and replaced the 100p with a 10p capacitor, and dfinally, we reset it and change the resistor for  ohm.
In task 1.3, we built the circuit showing on Figure 6 on the breadboard, we displayed the signal on the osilloscope and measured the time delay .
For task 2.1 we built the circuit in Figure 7 on the breadboard and also in LT Spice, We calculated, simulated and measure the time delay and Vo/Vin of this circuit.
In task 3, we learned about the circuit model of the oscilloscope probe we used in lab.
In task 3.1, We used circuit from figure 8 to attenuate the DC voltage first, we built the circuit in LT Spice, design the unknown resistor value to make Vo/Vin = 1/10, in DC.
And finally, in task 3.2, We took the circuit from Figure 9 and design the capacitance value.

4. Results


Figure 1 Original circuit and behave.


Figure 2 Circuit  with a reduce voltage from original, from 5v to 2v.


Figure 3. 5v, 1u, 2.1u and .tran 1u. changed.


Figure 4. Original parameters, now using 10p for Capacitor.


Figure 5. Original parameters, now using 100 resistor instead of 1k.

Figure 6 Schematic for task 1.3, breadboard,oscilloscope square signal shoing the cap fully charged and calculations.

Figure 7. Circuit for task 2.1, schematic, breadboard, oscilloscope, function generator and calculations for a 10x attenuation.


Figure 8 Circuit for task 3.1 Compensated probe for 10 DC Attenuation.


Figure 9 Circuit for task 3.2 Compensated probe for 10 DC and AC Attenuation.




5. Discussion

In this lab we used LT Spice to keep getting to know how powerfull tool it is. We saw the different changes that affect a RC circuit and how the signal changes while changing the components for better ability for charging to the full capacity, and the other circuit we can see how all the different methods match just fine. and we learned to attenuated the DC and AC signals. Defenally a great Recap for LT Spice.