what is the minimum input for a 7805 regulator?

Question

If I use a 7805 (5V regulator) for output of 5V at a constant stream, what do I need to use for input power to get a good output stream?

I know it needs to be a DC motor, (RPM's will be high enough) what is a good motor to use?

Answer 1

Go here : http://www.fairchildsemi.com/ds/LM%2FLM7805.pdf

The input voltage (Vi) is 10 V. See page 3.

Answer 2

The 7805 regulator is commonly used to provide a Steady 5V DC supply typically for TTL circuits. It is often used when the supply is AC mains transformed down to about 9 V AC rectified to DC then the 7805 voltage regulator provides a steady 5 volts DC as long as the input is 5V DC or more. I believe your original answer to be incorrect. Build the circuit with a 6V DC supply and try it if it doesn,t work increase the voltage The problem with AC mains is that it does fluctuate depending on load conditions therefore the reduced AC voltage will also fluctuate so it is best practise to have a higher than required AC voltage then use a rectifier/voltage regulator. If you are using 6V DC input from batteries then the 7805 Regulator should work OK. It is good for up to 35 V DC input. From the tech specs on your own link the max current is 1 Amp

Answer 3

7 volts, but it depends on the current. Download the datasheet and study it. If you are going to use a part, you should be familiar with all it's specs.



For a LM7805, at 1 amp, you need 7.5 volts.



What is all this about "current streams" ?



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