EECE 315, Design HW 01

NameAndrea Coetzer

Student ID005639830

Due Date02/27/2015

CollaboratorsNo collaborators

Title: Full Wave Bridge RectifierIntroduction: The purpose of this design is to input sinusoidal ac voltage with an 8V peak-to-peak voltage at a frequency of 2000 Hz and convert it to a DC output voltage. The design of the circuit includes four 1N4148 diodes, a resistor greater than or equal 2k, and a capacitor. PSpice was used to aid in the design as well as simulate the generated output function.Design Analysis:In order to design this circuit, all component values must be known. The purpose is to decrease the ripple voltage ( to as close to zero as possible. According to our textbook, Microelectronics Circuit Analysis and Design, 4th Ed., ripple voltage is defined as (equation 2.9), where is the peak output voltage (8V), is the input signal (2kHz), and RC is the resistance and capacitance respectively. This leaves us with three unknowns: , R, and C. Since the ripple voltage needs to be as small as possible, we can assume . According to the design parameters, the resistance has to be at least 2k, so we can assume this value in order to find the capacitance. The circuit can then be rearranged to determine the capacitance:. After plugging in all the known values, we can determine that the capacitance required is 1000.Using PSpice to simulate the design, the following graph was generated:

This simulated output confirms that the design and calculated values are satisfactory. There is a very low ripple in the output voltage shown in red.

Apparatus Diagram:

Experiment Procedure:1. Set the oscilloscope to generate an 8V p-p voltage at a frequency of 2kHz.2. Using the apparatus diagram, model the circuit on a breadboard.3. Capture the output voltage of the circuit on the oscilloscope.4. Take a screen capture of the Vin v. Vout. 5. The output voltage should look very close to linear.

Data:Discussion:The experimental results are mostly what were expected. The input ac voltage gets cut off at the negative peak. This could possibly have been due to the capacitor being connected to ground along with the input voltage and therefore smoothing the peaks. The output voltage shown in blue, is as expected. The results show that the RC values chosen in the rectifier are correct since it smoothes the ac voltage into a linear DC voltage.

1The diode bridge in the circuit directs the current to flow into the direction of the capacitor and the load resistor. While the ac voltage input is in its positive half cycle, D1 and D2 (refer to apparatus diagram) are in forward bias mode while diode D3 and D4 are in reverse bias mode. The two diodes in forward bias mode allows the current to flow and causes a voltage drop, while the two diodes in reverse bias acts as a short, therefore prohibiting current to flow in that direction. In the negative half cycle of the input voltage, D1 and D2 are in reverse bias while D3 and D4 are in forward bias. This orientation of the 4 diodes, allow the current to flow in the same direction during both the positive and negative cycle of the input voltage.Conclusion:The design of this circuit has taught me how to use diodes to ensure current flows in the desired direction. Its purpose was to learn how to transform a sinusoidal voltage into a steady state. In addition, it taught me how to filter the input by using a capacitor and resistance by determining the appropriate RC constant to reduce the ripple of the voltage.