1.    Introduction

The objective of this assignment is to design and evaluate a stabilised discrete linear power supply. The power supply requires to be designed according to the specification outlined below and evaluated using a circuit simulator.

2.    Specification
A stabilised discrete linear power supply requires to be designed. The power supply can only use discrete components, e.g. transformer, resistors, diodes, transistors, etc. The only exception is Operational Amplifiers (opamps) which may be used. The power supply requires to conform to the following specifications:

• Input Voltage: mains 230V, 50Hz
• Output Voltage: 7V
• Maximum output current: 1.5A
• Short-circuit protection
• Current limiting
• Low quiescent current.

The power supply requires to be able to cope with input voltage changes as well as with load current changes (Line regulation & Load regulation).
Using the circuit simulator, calculate the performance of your design with respect to:

(i)  Power consumption (based on quiescent current)

(ii) Dropout voltage

(iii) Ripple rejection

(iv) Load regulation (as %)

(v)   Line regulation (assume ±10% variation on mains voltage).

Compare your results with a simulation of a standard IC linear regulator of your choice (e.g. 7805).

3.    Report

Your report for this assignment should contain,

• schematic diagrams,
• calculations for all component values,
• a description/justification of your component choices,
• the simulation results
• a critical evaluation of your design