This project is to show how diodes can be used to tell if there a temperature difference using two diodes. The equation to find the voltage across the diode has temperature as one the dependent variables, and it is pretty reliable. The reason why resistors are not used because the TCR, or the variable that measures how much the resistance changes due to temperature, is because it is a linear term, instead as in the voltage across diode where the temperature affects the voltage exponentially and reliable. The TCR of an resistor also can be a positive number or a negative number, which means that a as tool to see if there is a temperature differential. This project idea was taken from the wiki of Analog Circuits, as one of their suggested projects.
Fig 1. Circuit Schematic of the Temperature Differential Voltage Circuit
I used the circuit diagram proved by the wiki of Analog Devices, as shown by Fig 1, with the voltage source being the power supply that was made as the class project for EE 98, the Introduction to Circuit Analysis class at San Jose State University. The project was to use a LM370 linear voltage regulator and voltage division to make a stable, variable voltage source. The way that multiple voltage levels of were achieved by voltage division using multiple resistors that are close to the same value. Using the switches, the voltage supply was around 5 V.
The first way that I measured the voltage difference of the two diodes in the ice water, then outside at room temperature during the summer months of 2018 in Central Coastal California, thirdly using my fingers then my forehead as a human body temperature gauge, and lastly both probes in boiling water. The reason why the both diodes were put in the same temperature and at multiple temperature levels were because there is an voltage offset. After finding out the voltage offset, the next step was finding the voltage difference between ice water and boiling water. The reason why these two values were important because of the fact that 0 C is the freezing point of water and 100 C is the boiling point of water, which was used to create the Celsius scale. After these steps, then I tested the other temperature differences, and the bigger the difference, the bigger the voltage.
Related Links:
Analog Devices Wiki Link: https://wiki.analog.com/university/courses/electronics/electronics-lab-25
EE98 Final Lab Report: https://www.dropbox.com/s/aiohbdxfk050lj9/EE%2098%20Final%20Report.pdf?dl=0
Fig 1. Circuit Schematic of the Temperature Differential Voltage Circuit
I used the circuit diagram proved by the wiki of Analog Devices, as shown by Fig 1, with the voltage source being the power supply that was made as the class project for EE 98, the Introduction to Circuit Analysis class at San Jose State University. The project was to use a LM370 linear voltage regulator and voltage division to make a stable, variable voltage source. The way that multiple voltage levels of were achieved by voltage division using multiple resistors that are close to the same value. Using the switches, the voltage supply was around 5 V.
The first way that I measured the voltage difference of the two diodes in the ice water, then outside at room temperature during the summer months of 2018 in Central Coastal California, thirdly using my fingers then my forehead as a human body temperature gauge, and lastly both probes in boiling water. The reason why the both diodes were put in the same temperature and at multiple temperature levels were because there is an voltage offset. After finding out the voltage offset, the next step was finding the voltage difference between ice water and boiling water. The reason why these two values were important because of the fact that 0 C is the freezing point of water and 100 C is the boiling point of water, which was used to create the Celsius scale. After these steps, then I tested the other temperature differences, and the bigger the difference, the bigger the voltage.
Related Links:
Analog Devices Wiki Link: https://wiki.analog.com/university/courses/electronics/electronics-lab-25
EE98 Final Lab Report: https://www.dropbox.com/s/aiohbdxfk050lj9/EE%2098%20Final%20Report.pdf?dl=0
Comments
Post a Comment