Engineering 44 initials (Kuo-Hao) Jeff Liao: March 2015

Tuesday, March 31, 2015

Day 10 03/26/2015 Inverting Voltage Amplifier

At the first we have talked about the diff Vout

Then we talk about the more function amplifier which is a simple operational amplifier-based circuit.

At this one we discover the inside of Op-amps and know the Rin will be much smaller than Rout and the ratio of v source and v out will be the ratio of its resistor next to

Since Vo is 20 k and Vs is 10 k the ratio of Vo and Vs is around 2

Also remember the 5 components of circuit

Diode
Current Supply
Voltage supply
Resistor
Transistor

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Another Practice of Op-amps

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Inverting Voltage Amplifier

First this is what we circuit we are using for replace the one on the lab book

And Vout = R1/R2 Vin by we know the Vout and Vsource is base on the ratio of resistance.

To understand the Op-Amps we need to know what its each connection means and in here we use

inverting input 2 connect to R1 = 2k
non-inverting input to ground and R2
-V supplied by -5V
+V supplied by +5V
output by R2

Then we measured

Vout = 3.71 V and Vin=1.73V by plug into Vout = (R1/R2) Vin the Vout is 3.7 V

Here comes the graph that when Vin change and the graph compare Vout vs Vin

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The ratio of voltage is depend on its resistance

If the Op-amp its resistor is zero

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Day 09 03/24/2015 Non-Ideal Power Sources & Maximum Power Transfer

Non-Ideal Power Source

This lab is focus on solving the internal resistance from the power, so we need to reduce the circuit resistance to the point where we can measured the internal resistance

Pre-Lab

In the pre-lab we first calculate the ideal voltage source which means not include the internal resistance, and calculate the non-ideal voltage with internal resistance Rs.

Next the lab begin

we first measured and record the resistor of circuit. You can see we measured a close circuit resistor by simply connect power supply and ground to the voltmeter.

Next step

I made a circuit above and internal resistance is the wave-form generator inner resistance.

Then I come out with this

For the closed circuit Vout we got 0.972 V and we supply the open circuit 0.99 V gave me Voltage out with 1.001 V with 22.3 resistor connect to the power source. To be able to measured the resistance in source we used equation Rs = (R-Vout*R)/Vout (P.S The Vout we used here is closed circuit)

Maximum Power Transfer

This lab main point is to transfer the max power to a 2.2 resistor

Pre-Lab

The formula is easy with Rload given as 2.2k the Pmax = (Vth)^2 / 4*(Rload)

Procedure

we first set up the circuit as the one drew on Pre-Lab

We measured the resistor as 2.18k and Vth = 2.48 so plug into the formula from pre-lab the max power is 2.82mW

Then we compared to the pre-lab the percent error is low as 0.70%

Tuesday, March 24, 2015

Day 08 03/19/2015 Getting Started with EveryCircuit, Thevenin's Theorem

Getting Started with EveryCircuit

Circuit need to set up by

web: everycircult.com/app/

Result

Practice

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Thevenin's Theorem

The main purpose for this lab is to be able to determine the Thevenin resistance and the open-circuit voltage

The circuit must set up

prelab calculation of Voc and RL

On calculation of RL, we need to first ignore all the power source (Hint: on Thevenin Theorem power source can be off if needed to calculate anything) Then we can simply find the RL by combine all resistance by either parallel or series method.

The Voc can be find by first calculate I1 and I2 then solve V1 and V2 by times current I1 and I2 by its resistance then the Voc can be simply solve out by adding to voltage.

circuit set up

Step 2

Voc

Thevenin resistance

On Step two we measure the voltage (Voc) across terminals a-b and Thevenin resistance(Rth) at terminals a-b.

The result come out is very closed to our theoretical value from pre-lab.

Step 3

Voltage across terminal a-b

On step 3 we determine pick a load resistance RL (4k<RL<10k) range.

We picked 7.9 kmo.

We know the Va-b must be Voc / (Rth + RL ) * RL

As the result the experimental value is very closed to out theoretical value.

Step 4

set up Thevenin circuit

The circuit is simplify to a series which transistor is 7.2 kmo and a power supply with RL 7.92kmo.

Then we measure the Va-b again which here is transistor and I got value of 0.28V which is very close to the one I has on Step 3 which is 0.242V.

Step 5

Set up Circuit which one is Rth=7.2kmo and another one is the one for me to simply change resistance.

minimum

maximum

Data Table

On the setup I measure the resistance with different method

On transistor there are three branch and I measure resistance on the center branch and the other one that not connect to the circuit. As the result Rload should equal to Rmax - Rmeasured.

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Class Work

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Day 07 03/17/2015 Time-varying Signals and extra (A BJT Curve Tracer)

Lab: Time-varying Signals

This lab is mainly focus on using waveform generator to general the wave vs. time oscilloscope.

Graph of circuit

Graph of Vin and Vout .Top: Vin Bottom Vout

On this pre-lab we understand with resistor R1 = R2, the Vin pass R1 will appear to be the top graph of second graph with amplitude = A, and since Vout will require current to pass R1 and R2, the resistor for Vout is 2R because R1 = R2. With twice larger resistance the voltage will decrease by half and it lead up to the bottom of second graph with only half of amplitude which is A/2.

Lab Procedures:

V1in Graph

We first set up the figure 1 which is a sinusoidal voltage with amplitude 2V and frequency 2kHz.

V1out Graph

The Vout amplitude is 1V and its frequency is same as 2kHz.

The Vout amplitude is 1/2 of Vin as what I expect from pre-lab.

V2in

Same for the first one we set out figure 2 with triangular wave with amplitude 2V and frequency 2kHz

V2out

The Vout amplitude is 1V and frequency is 2kHz which Vout amplitude is 1/2 of Vin as what I expected to see.

V3in

Last is the square wave which I also put in 2V for amplitude and 2kHz frequency

V3out

The Vout has also provide 1/2 amplitude of Vin which is 1V and still keep the same frequency of 2kHz

A BJT Curve Tracer:

This lab is mainly for use to understand the transistors

On this circuit setup we can see transistor has separate to 3 different path one for Ic to flow in one is connect to ground and one for Ib to flow in.