## Design Project for EE 311

The design project is worth 20 % of the course grade

Design a power supply that generates a DC voltage of your choice (between 3 and 12 Volts) from 120 VAC line voltage.

**Design Specifications:**

• The load power at full load must be at least 500 mW.

• The % ripple at the DC output must be less than 1 % at full load and no load conditions.

• The % voltage regulation must be less than 10 %.

• The power supply must use a power transformer to step down from 120 VAC. Several different power transformers are available in the lab.

• No overheating. A person should be able to touch all components (on the low voltage side of the transformer) without injury due to excessive heat. Temperature < 70C for all components on the low voltage side of the transformer at full load and at no load conditions.

• Safety: No exposed high voltage (120 VAC) wires. All components must be properly rated with a margin of safety.

**Design Constraints:**

• The design must select components from this list: AC power cord, power transformer(s), Zener diode(s), silicon diode(s), resistors, capacitor(s), electrical tape, solder, breadboard, connecting wires. It is not required to use all of these components.

• The total capacitance used in the design must be no more than 1 mF.

• The design must employ one of the following rectifiers: full wave center tapped rectifier, full wave bridge, or half wave.

• Size: Prototype must be able to fit in a 6” by 10” by 4” box

• Weight: No more than 2 lbs.

• Cost: No more than $20 for a quantity of 10000.

The final design will indicate the recommended power rating for all resistors and the recommended voltage rating for the capacitor.

The final design will indicate the recommended power rating for all resistors.

The final design must be signed off by the instructor.

Available Diodes in the Labs

A Group Report is due Wednesday Nov. 30

Design Project Report

**Experiment Title: THE BRIDGE FULL WAVE RECTIFIER**

**Objective:**

Equipment List:

• Breadboard.

• Wires.

• 1 Capacitor of

power Transformer 31.7

Zener diode of 6.2

Specify all components.

Include the recommended resistor power ratings and the capacitor voltage rating.

The information above is 10 % of the report grade

Design Description (40 %):

Explain how a Zener diode regulator works.

Draw a schematic diagram of the final design in LT Spice or other software.

Explain how the circuit works.

Show all design calculations steps to solve for the following items:

• % ripple voltage

• % voltage regulation

• Power in the series resistor

• Power in the load resistance at full load

Be sure to add a sentence between each equation.

Provide an Excel spread sheet of calculation results

or provide MATLAB code and values calculated from the code

Make a table for them

VAC = 31.7;

Vp =sqrt(2)*(VAC);% this is teh peak of the secoadary voltage

Vc = Vp – 1.4; % add an equatin for Vc

Vz=6.2;

% need to calculate Rl

% power = 0.5 Watts Pl = Vl ^2 / Rl

PL = .5; % Load power in Watts

RL = Vz^2/ PL;

IL=Vz/RL;

Rs=450;

C=1*10^(-3);

f=60;

Irs = (Vc-Vz)/ Rs;

Prs=(Irs)^2*Rs;

Prl= (Vz)*(IL);

delta=1/(2*f);

Vc_ripple= ((Irs*delta)/(C));

Zz=2;

Rpar = (Zz*RL)/(Zz+RL)

Q= Rpar/(Rpar+Rs)

Vout_ripple= Vc_ripple*(Q);

Ripple=(Vout_ripple)*100;

fprintf(‘THE PERCENT OF RIPPLE IS %.4f \n’, Ripple);

Experimental Data/Analysis (40 %):

Conduct an experiment that will collect all data (DMM measurements and oscilloscope screen shots) to confirm the design specs.

1) Perform and record measurements needed to calculate % ripple.

2) Perform and record measurements needed to calculate % voltage regulation.

3) Perform and record measurements needed to calculate power in the series resistor at full load and at no load

4) Perform and record measurements needed to calculate power in the load resistor at full load

Explain what measurements you made to get the results.

Provides tables and screen shots as necessary to display results. As a minimum, provide a table of all measurements. Include all voltages, currents and resistances measured in the lab. Provide a heading for each table. Number all figures and provide a caption for each figure. Describe what is shown in each figure and in each table.

From your measurements, show the calculations for the following items:

• % ripple voltage

• % voltage regulation

• Power in the series resistor

• Power in the load resistance at full load (500 mW)

Did you meet design specs?

Provide a suggested power rating for RS and RL.

Provide a table of parts, part numbers, supplier, and cost. List the unit cost as if buying a quantity of 10000 to come up with a rough estimate of the manufacturing cost.

Include a solderable breadboard or a solderable printed circuit board (PCB)

Conclusion (10 %):

Provide a summary of the results and indicate if all design parameters were met.

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