3/17/2015

Pre-Lab

We began the day with a lab that required the use of a function generator and oscilloscope. We used the Analog discovery for both. Before we started the lab we predicted what would happen if we were to use a voltage divider on a time varying voltage source. We predicted that the voltage will be cut in half.

Circuit

We built the circuit and connected the Analog Discovery to supply a time varying voltage of different shapes (triangle, sinusoidal, square) tot the circuit. We then used the oscilloscope to record the result.

Square Generator

Triangle Generator

Sinusoidal

As can be seen by the results from the oscilloscope, the amplitude (voltage) was halved with the voltage divider, from 2V to 1V. 

Circuit Diagram

The next lab required the use of the analog discovery as well. To build the circuit above the use of a NPN transistor (2N3904), a 100 Ω, and a 100kΩ resistor. Using the oscilloscope, we graphed the voltage from the 100 Ω resistor and the NPN transistor.  Using Waveforms, we were able to create a step function and send it through the base. We also sent a triangle function through the collector.

Circuit

Above is the circuit built.

Graph using oscilloscope

Saturation with a NPN transistor.

Summary:

Today, we focused primarily on labs. The first lab consisted of getting to know how to use the Analog Discovery and Waveforms to act as both a function generator and oscilloscope. The other lab required the knowledge from the previous lab in order to complete it.Towards the end of the class we learned three new methods of circuit analysis. The three new methods are linearity property, superposition principle, and source transformation. The linearity property can only be applied to linear circuits, which is a circuit whose output is linearly related to its input.The superposition principle applies to circuits where the voltage across an element in a linear circuit is the sum of the voltages across that element due to each independent source. Source transformation allows us to  replace a voltage source in series with a resistor by a current source is in parallel with a resistor. This also applies to current sources.