Week 6, 2/15/2016 - 2/19/2016:
Operational Amplifiers

Explanations of the pin numbers are below:

This picture explains how to set up the amplifiers

1. You will use the OPAMP in open-loop configuration in this part, where input signals will be applied directly to the pins 2 and 3. a. Apply 0 V to the inverting input. Sweep the non-inverting input (Vin) from -10 V to 10 V with 1 V steps. Take more steps around 0 V (both positive and negative). Create a table for Vin and Vout. Plot the data (Vout vs Vin). Discuss your results. What would be the ideal plot?

In the open loop, the OPAMP has a very large gain. When the input is positive, output will reach the maximum value very quickly. When the input is negative, output will also reach the minimum value fast. Around you can see the line is almost perpendicular. In this condition, the OPAMP is hard to control so that it will not help us get the ideal voltage value.  I deal plot is really similar to this, when the input is 0, the output is 0. The line is perpendicular. However, in this graph, the line is a little bit inclined.

This graph compares the input to output voltage on a non inverting OPAMP

Input	Output
-5.1	-3.84
-4.2	-3.84
-2.5	-3.84
-1.3	-3.84
-0.067	-3.84
-0.33	-3.84
-0.28	-3.84
-0.19	-3.84
0.25	4.5
0.36	4.5
0.45	4.5
0.7	4.5
1.15	4.5
2.3	4.5
3	4.5
4.1	4.5
5.15	4.5

This chart displays our input and output values

We had results similar to an ideal plot. Our amplifier worked as expected.

 b. Apply 0 V to the non-inverting input. Sweep the inverting input (Vin) from -10 V to 10 V with 1 V steps. Take more steps around 0 V (both positive and negative). Create a table for Vin and Vout. Plot the data (Vout vs Vin). Discuss your results. What would be the ideal plot?

Same to the question 1.  in this OPAMP, the gain is really hih. And the output will reach the maximum and minimum value very quickly. It's hard to control and lack precise so that we could not use it in real to get the voltage what we want. the ideal plot for this graph is when the input is 0, the line will be perpendicular. In the graph below, the line has a little bit inclined, which means that the output is 0 when input is 0.

This graph compares the input to output voltage on an inverting OPAMP

Input	Output
5.03	-3.84
4.15	-3.84
2.98	-3.84
1.3	-3.84
0.53	-3.84
0.32	-3.84
0.25	-3.84
0.14	-3.84
-0.22	4.5
-0.39	4.5
-0.54	4.5
-0.73	4.5
-1.17	4.5
-2.34	4.5
-3.02	4.5
-4.18	4.5
-5.09	4.5

This chart compares our input and output values

We had results similar to an ideal plot. Our amplifier worked as expected.

2. Create a non-inverting amplifier. (R2 = 2 kΩ, R1 = 1 kΩ). Sweep Vin from -10 V to 10 V with 1 V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.
The gain here is three. We used resistor to control the gain so that the maximum  and minimum value will not be reach very quickly.

Input (V)	Measured (V)	Calculated (V)
-4.98	-3.58	-5
-4.01	-3.58	-5
-3.05	-3.58	-5
-2.53	-3.58	-5
-2	-3.58	-5
-1.59	-3.58	-4.77
-1.1	-3.3	-3.3
-0.99	-2.97	-2.97
-0.69	-2.08	-2.07
-0.5	-1.5	-1.5
-0.24	-1.17	-0.72
0.22	0.67	0.66
0.3	0.92	0.9
0.45	1.36	1.35
0.59	1.78	1.77
0.8	2.7	2.4
0.96	2.9	2.88
1.57	4.13	4.71
1.9	4.13	5
2.53	4.13	5
3.02	4.13	5
4.04	4.13	5
4.99	4.13	5

This chart compares our input and output values

This graph compares the voltage values of a non inverting amplifier

3. Create an inverting amplifier. (Rf = 2 kΩ, Rin = 1 kΩ). Sweep Vin from -10 V to 10 V with 1V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.

The gain here is two. We used resistor to control the gain so that the maximum  and minimum value will not be reach very quickly.

Input (V)	Measured (V)	Calculated (V)
4.76	-3.51	-5
3.71	-3.51	-5
2.8	-3.51	-5
1.55	-3.1	-3.1
2.01	-3.45	-4.02
1.06	-2.58	-2.12
0.67	-2.1	-1.34
0.55	-1.9	-1.1
0.47	-1.66	-0.94
0.36	-0.77	-0.72
0.27	-0.65	-0.54
-0.27	0.54	0.54
-0.3	0.6	0.6
-0.51	0.92	1.02
-0.62	1.21	1.24
-0.98	1.45	1.96
-1.58	2.6	3.16
-2.28	3.52	4.56
-3.27	3.52	5
-4.45	3.52	5
-4.96	3.52	5

This chart compares the input and output voltage values

This graph compares the voltage values of an inverting amplifier

4. Explain how an OPAMP works. How come is the gain of the OPAMP in the open loop configuration too high but inverting/non-inverting amplifier configurations provide such a small gain?

OPAMPs set voltage to two specific levels. Any value before 0 it will set to X and any value after 0 it will set to Y. OPAMP gains can be too large when there is a very small amount of voltage being bumped up to a higher voltage. Inverting and non inverting amplifiers can have a smaller gain because their gain is based off of a ratio between two resistors. Depending on the resistors you may not have much gain at all.

Temperature Controlled LED System:

This picture labels the pins in the temperature sensor

Using a voltage meter, measure the output voltage from the VOUT. Now put your finger (or cover the sensor with your palm) on the TMP36 temperature sensor for a while, observing how the output voltage changes. Check Fig. 6 in the data sheet (EXPLAIN).

As you increase the temperature on the sensor, the voltage passing through increases. The video below explains this and shows our results.

This video shows how the temperature sensor allows more voltage as its temperature increases

Relay

This s a diagram of the relay we used
1.    Connect your DC power supply to pin 2 and ground pin 5. Set your power supply to 0V. Switch your multimeter to measure the resistance mode; use your multimeter to measure the resistance between pin 4 and pin 1. Do the same measurement between pin 3 and pin 1. Explain your findings (EXPLAIN).

The resistance between pin 1 and pin 3 will be ideally infinite because there is no connection there so that the current will not flow. The resistance between pins 1 and 4 was measured at very small difference values ranging anywhere from 50-100 Ohms.

2.    Now sweep your DC power supply from 0V to 8V and back to 0V. What do you observe at the multimeter (resistance measurements similar to #1)? Did you hear a clicking sound? How many times? What is the threshold voltage values that cause the switching? (EXPLAIN with a VIDEO).

When you sweep the voltage you will hear a clicking sound at around 5V and then again after you drop down to 2V. This clicking sound is the relay switching between the two pins. The video below explains in further detail and will show you the relay in real time.

This video shows the relay switching over while we sweep the voltage

3.  How does the relay work? Apply a separate DC voltage of 5 V to pin 1. Check the voltage value of pin 3 and pin 4 (each with respect to ground) while switching the relay (EXPLAIN with a VIDEO).

The relay switches over between the two connections. Before the relay switches over, pin 4 will read at 5V and pin 3 will not read any voltage. When it switches over, pin 4 will not read any voltage and pin 3 will read at 5V. A video describing this is below.

This video shows the results of the relay switching over with a voltage source on one of the pins.

LED + Relay

Turn LED on/off by switching the relay. Explain your results in the video. Draw the circuit schematic (VIDEO) 

This video shows us powering the LED using the relay system 

This is the circuit that we drew to power the LED. The voltage source is applied to the relay and when the relay switches over it will go to an OPAMP that will power the LED.

Operational Amplifier

.

1.  Connect the power supplies to the op-amp (+10V and 0V). Show the operation of LM124 operational amplifier in DC mode with a non-inverting amplifier configuration. Choose any opamp in the IC. Method: Use several R1 and R2 configurations and change your input voltage (voltages between 0 and 10V) and record your output voltage. (EXPLAIN with a TABLE)

R1 = 1 kilo Ohms, R2 = 3 kilo Ohms

Vin (V)	Vout (V)
.236	.905
.96	3.8
1.94	7.8
2.98	8.38
3.94	8.38
4.01	8.38
4.98	8.38
6.08	8.38
7.02	8.38
7.94	8.38
9.03	8.38
9.98	8.38

This chart compares 

R1 = 1 kilo Ohms, R2 = 2 kilo Ohms  

Vin (V)	Vout (V)
.216	.64
.98	2.95
2.01	6.03
3.04	8.38
3.99	8.38
5.02	8.38
6.03	8.38
6.95	8.38
8.12	8.38
8.87	8.38
9.96	8.38

     2. Use your temperature sensor as your input. Do you think you can generate enough voltage to trigger the relay? (EXPLAIN)

No, the temperature sensor has too much resistance we we do not have enough heat to allow enough voltage to trigger the relay. We would need to use an operational amplifier to step up the voltage in order to trigger the relay.

3.     Design a system where LED light turns on when you heat up the temperature sensor. (CIRCUIT schematic and explanation in a VIDEO)

This video shows 

4.     BONUS! Show the operation of the entire circuit. (VIDEO)