Thursday, February 11, 2010

5V power supply

5V power supply

Simple 5V power supply for digital circuits

Summary of circuit features

Brief description of operation: Gives out well regulated +5V output, output current capability of 100 mA

Circuit protection: Built-in overheating protection shuts down output when regulator IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit succesfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unreglated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input transformer cost

Circuit description

This circuit is a small +5V power supply, which is useful when experimenting with digital electronics. Small inexpensive wall tranformers with variable output voltage are available from any electronics shop and supermarket. Those transformers are easily available, but usually their voltage regulation is very poor, which makes then not very usable for digital circuit experimenter unless a better regulation can be achieved in some way. The following circuit is the answer to the problem.

This circuit can give +5V output at about 150 mA current, but it can be increased to 1 A when good cooling is added to 7805 regulator chip. The circuit has over overload and therminal protection.
  Circuit diagram of the power supply
The capacitors must have enough high voltage rating to safely handle the input voltage feed to circuit. The circuit is very easy to build for example into a piece of veroboard.

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