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Comment on Frankenstein power supply

Hi. I've attached a circuit diagram. The schematic is for a dc power supply. It's purpose it to charge nicad batteries. However, we are having trouble locating the transformer.

The transformer has been omitted, and the power is just represented by an AC power source.

I'm a little unclear about the C-L-C portion of the circuit (Pi network?), the purpose of the transistor, and how the zener diode is operating in its current position.

If you could spend a little time, please walk me through how the current and voltage are changing through these portions of the circuit, how the filtering is working, how the ripple is being affected, and how the voltage is being regulated.

Also, if you could point out significant features that would be nice too.

It's not a complicated circuit. There are just some features I don't understand. Thanks.

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In general we can summarize the functions of the blocks of the circuit as follows:

Rectifier - converts AC to DC, but the DC output is varying. I will assume that you know how this works.
Smoothing LC filters- smooths the DC from varying greatly to a small ripple.
Regulator using Zener diode and transistor - eliminates ripple by setting DC output to a fixed voltage.

Now, we will see detailed description of these blocks.

The bridge rectifier outputs not pure DC but ripple voltage of double the supply system frequency. But most electronic circuits including the NiCad charger you mentioned require almost pure dc voltage and the pulsating output of ...

Solution Summary

This solution is provided in 457 words. It discusses rectifiers, smoothing LC filters, and regulators as the main features of the system, as well as further explaining each.

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