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 overload and thermal protection. 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.
- C1 = 100uF-25V electrolytic capacitor, at least 25V voltage rating
- C2 = 10uF-25V electrolytic capacitor, at least 6-16V voltage rating
- C3 = 100nF-63V ceramic or polyester capacitor
- IC = 7805 regulator IC
IC’s Pinout :
- Unregulated voltage in
- Ground (See Diagram)
- Regulated voltage out
- Gives out well regulated +5V output, output current capability of 100 mA
- Built-in overheating protection shuts down output when regulator IC gets too hot
- Very simple and easy to build
- Very stable +5V output voltage, reliable operation
- Easy to get components, uses only very common basic components
- Based on datasheet example circuit, I have used this circuit succesfully as part of many electronics projects
- Part of electronics devices, small laboratory power supply
- Wide range of input unreglated DC 8-24V power supply
- Few dollars for the electronics components + the input transformer cost
More output current:
If you need more than 150 mA of output current, you can update the output current up to 1A doing the following modifications.
- Change the transformer from where you take the power to the circuit to a model which can give as much current as you need from output
- Put a heatsink to the 7805 regulator (so big that it does not overheat because of the extra losses in the regulator)
More output voltages:
If you need other voltages than +5V, you can modify the circuit by replacing the 7805 chips with another regulator with different output voltage from regulator 78xx chip family. The last numbers in the the chip code tells the output voltage. Remember that the input voltage muts be at least 3V greater than regulator output voltage ot otherwise the regulator does not work well.