30-05-2012, 04:25 PM
DC Power Supply
Project 1 Power Supply.doc (Size: 49.5 KB / Downloads: 454)
In this project you will construct and analyze a DC power supply. An example circuit is given in Figure 1. You may implement an alternate circuit with the permission of the instructors. All component types in the example circuit are available in PSpice libraries for simulation.
I. Performance Specifications:
Your circuit must meet the following specifications:
Output Voltage: 9, 10, 11 or 12 Volts (select one), accurate to ±50 mV
Output Power ≥ 1.0 Watt
Output Ripple ≤ 50 mV (peak to peak)
Load Regulation * ≤ 0.2%.
Line Regulation * ≤ 50 mV/V
No capacitors larger than 1.0 mF (1000 µF)
* Load regulation is defined as (unloaded voltage – loaded voltage)/(unloaded voltage). Loaded voltage will be tested at 1 Watt output.
* Line regulation will be tested by varying the AC input by 10% and measuring the change of the dc output voltage. It is calculated as (output voltage – varied voltage)/(output voltage).
Simulation
1. Your output voltage level will be assigned in lab. Determine the component differences between your circuit and the example circuit. The provided transformer will provide either 20Vpp or 40Vpp depending on your configuration. A list of active components available is on the last page. You are free to use other components, but you must purchase them yourselves. Resistors are available in the lab.
2. Simulate your power supply in Microsim PSpice. Drive your circuit with an ac source(Vsin) having a frequency of 60 Hz and an amplitude which matches your transformer design.
Fabrication
0. Obtain characteristic curves for each of the active devices you actually use. Determine the beta of the transistors and the Vz of the zener diodes. If possible use this information to improve the accuracy of your Spice models.
1. Construct your circuit on a breadboard. Assemble your circuit carefully - you will only be given one set of parts. Again, work block by block. This is easier that trying to debug the entire circuit.