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.