1st meeting: brief idea

Today my partner and I went to meet our supervisor for the first time in order to get a better understanding of the puepose and check some details of the project. The supervisor introduced the main functions of the project and the basic structure of the circuit to us. He also made it clear to us about what to do to prepare for the project which will come in the first 5 weeks of next semester. He suggested us to search google for some circuits, and simulate them on computer to see whether it can meet the requirements of the project. After the determination of the circuit, we should come up with an electronic component list of what we may need to build out circuit, ad hand it in to the technicians in the lab.

An ideal constant voltage power supply would have zero output noise at all frequencies. Thus, as shown in the figure below, the output would remain perfectly constant in spite of any changes in the output current demanded by the load.

A simple unregulated power supply consisting of only a rectifier and a filter is not capable of providing a ripple free DC output voltage whose value remains reasonably constant. In this project,to obtain such a approximation of the ideal output with characteristic of the figure, some type of control element (regulator) must be included in the supply.

In practical, a transformer can drop a high user-voltage to a low AC signal, and then a bridge circuit can rectify such a small AC signal to a DC input, but there is still some rest AC wave cannot be rectifies to affect the output. Thus now, through discussion and analysis, our supervisor suggested us ignore the transformer and bridge circuit. What we need to design is a regulator circuit works with a DC input provided by the power supply on lab bench along with a small AC signal as the input noise, so that we can check whether the output voltage can be regulated to a constant DC voltage regardless of the AC ripple in the input. For the sake of offsetting the noise (the small AC signal in the figure), we can invert the AC signal to a completed opposite direction AC signal. And then the original and inverting AC noise are able to counterbalance each other, so that only the constant DC voltage can be left and output.

What is regulated linear DC power supply?

When we received this project, firstly we should know the definition and functions of the regulated DC power supply.

A regulated DC power supply can be also named a (voltage) regulator. It consists of a embedded circuit which may be a simple "feed-forward" design or may include negative feedback control loops. The circuit should use some electronic components, like resistors, capacitors, zener diodes, diodes, transistors, operational amplifier and so on.

Depending upon the designing of the circuit, a regulated power supply can be used to regulate one or more AC or DC voltages. However, this project only focuses on the regulated linear DC power supply. The designed circuit of this project should be able to power the load which must be operated within certain power supply limits. The output from the regulated linear DC power supply should be able to be adjusted linearly within a certain range and nearly always DC voltage regardless of the AC ripple from the input.

Actually, voltage regulators have been widely applied in variety of fields, from electronic products to electrical systems. For instance, if without voltage regulators in the computer power supplies to stabilize the DC voltages, the processors of the computers will make bugs and generate error and irregular signals to the following system units, then the system of the computer will be in disorder and the whole computer cannot work normally.