Created by
Created February 29, 2012
Last modified March 06, 2012
Tags 1n4007   5v   7805   9v   pp3   tantalum  


How to use a 9V PP3 battery to power a 5V circuit.


This circuit will allow you connect a 9V PP3 battery to supply 5V for your projects. The resistor and LED are optional. The 220ohms allows 23mA to go to the LED. You could use a higher value resistor as long as the current is sufficient to light your LED.

The diode D1 protects the 7805 voltage regulator in case you connect the battery the wrong way round.

The capacitors values are recommended by the voltage regulator manufacturer. They help smooth out the voltage and reduce spikes and oscillations. I used tantalum capacitors because that's what the datasheet said but I've since looked at other datasheets and ceramic ones will do as well.


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