Lab 6

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.

Non-Inverting Input (V)	Output (V)
-5 < X < 0	-4.09
0	0
0 < X < 5	4.49
Inverting Input (V)	Inverting Output (V)
-5 < X< 0	4.49
0	0
0 < X < 5	-4.09

Table: Both inverting and Non-Inverting outputs hit a stable max and min value when above zero

Picture: Non- Inverting inputs with respective outputs

a. Apply 0 V to the inverting input. Sweep the non-inverting input (Vin) from -5 V to 5 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?

        When plugging in voltage values for the Non-Inverting input, all of the values below zero became a max value of -4.09 volts. While anything above zero became 4.49 volts. The ideal plot would have both the negative min and positive max of negative five and positive five.

Picture: Inverting inputs with respective outputs

b. Apply 0 V to the non-inverting input. Sweep the inverting input (Vin) from -5 V to 5 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?

        Much like the Non-Inverting input, the Inverting hit stable max and min values, however when a voltage lower than zero was plugged in the reading was 4.49. When a voltage above zero was plugged in the reading was -4.09.  The ideal plot would have both the negative min and positive max of negative five and positive five.


2. Create a non-inverting amplifier. (R2 = 2 kΩ, R1 = 1 kΩ). Sweep Vin from -5 V to 5 V with 1 V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.

Input (V)	Output (V)
-5 < input < -2	-3.77
-1	-2.57
-0.74	-1.89
-.50	-1.23
0	0
0.05	1.9
0.70	2.43
1	3.78
2 < input < 5	4.24

Table : This table shows values for Non-Inverting amplifier when varied from -5 to 5 volts

Figure : Plot of Non-Inverted Opamp Output Voltage Versus Input Voltage

3. Create an inverting amplifier. (Rf = 2 kΩ, Rin = 1 kΩ). Sweep Vin from -5 V to 5 V with 1 V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.

Input	Output
-5 < input < -2	4.21
-1	2.23
-0.73	1.80
-0.48	1.30
0	0.10
0.50	-0.62
0.74	-1.15
1.10	-1.84
2	-3.645
3 < input < 5	-3.70

Table; This table shows values for the Inverting amplifier when varied from -5 to 5 volts

Figure : Plot of Inverted Opamp Output Voltage Versus Input Voltage

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?

An op amp works by amplifying the difference between the two input terminals to potentially supply a high voltage to the output terminal, which is limited by the supply voltage. This amplification, otherwise known as the gain is usually extremely high in open loop operational amplifiers (around 100,000). This means that even a small input voltage going through the circuit will result in an output voltage that is close to the value of the supply voltage. In inverting and non-inverting op amp set-ups, however, a portion of the output voltage is connected back to the negative input voltage. This reduces the potential difference between the input terminals and thus decreases the gain of the op amp dramatically. 

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).

     When measuring the resistance between pin four and pin one, the multimeter gave a reading of 1.3 Ohms while when connected to pin three and pin one the multimeter displayed a reading of being overloaded.

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).
          The multimeter shows at first a reading then once the relay makes a clicking sound, the meter immediately displays a reading of overloaded. The clicking of the relay can be heard twice when the voltage is increased to eight and then decreased back down to zero. These clicks were measured at six volts and going down to two volts. 

Video 1: Relay "Click" Explanation

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).

Video 2: This Video explains how the relay works and shows how the added 5 volts affects pin 3 and 4

         For Pin four, when the voltage hits about six volts for the input the relay makes a clicking sound and switches the reading on the multimeter to overloaded. When decreasing the voltage from eight back down to zero the same sound can be heard when around two volts and the mulitmeter gives off a reading. When the multimeter is plugged at pin three, the relay once again clicks at six and going down at two volts however it starts off as overloaded then clicks and goes down to a readable number.

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

Video 3: Relay as an LED Switch explained

Picture: schematic for the circuit with a relay

1. Connect the power supplies to the op-amp (+10V and 0V). Show the operation of LM 124 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= 100 Ohm	R2= 100 Ohm
Input (V)	Output (V)
10 < X< 3	7.06
3	6.26
2	3.75
1	2.05
.5	1.02
0	0

Table: With both resistors at 100 ohms

R1= 47 Ohm	R2= 100 Ohm
Input (V)	Output (V)
10 < X < 2	6.63
2	6.43
1	3.045
.5	1.484
0	0

Table: One resistor is 47 Ohm and the other is 100 Ohm

R1= 1.2 k Ohm	R2= 100 Ohm
Input (V)	Output (V)
10 < X < 7	8.64
7	7.44
6	6.38
5	5.33
4	4.27
3	3.33
2	1.95
1	1.18
.5	.7
0	0

Table: One Resistor is 1.2k Ohm the other is 100 Ohm

      When the resistance was increased the change in voltage affected the reading much more than when there was only a small resistance. This data helps show how the resistance plays a vital role in the max value that the circuit can go up to. For example, In the first table, there are only five unique values while the third table (largest resistance) had ten unique values.

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

Figure: LED Relay Schematic Using Heat Sensor and Opamp

Although we were not able to build this circuit, we created this schematic based on earlier parts of the experiment and some hypotheses. As usual the Opamp will have a set maximum value, which is shown as 10V in the diagram, and the output of the Opamp is connected to the relay input. In the relay, the resistance can either be very high thus limiting the flow of current, or very low, allowing the LED to be lit. The temperature sensor will limit the amount of voltage that enters the opamp and thus the amount of voltage that enters the relay and thus the power in the LED.