Small DC Power Supply

Step 4 Regulation

This step is necessary to take the smoothed out voltage, smooth it out a little further and give you your final, desired output voltage.

Again, you could do this step in a couple of different ways. First you could whip up a zener regulator, if you happen to have zener diode around that fits the output voltage you wanted.

Personally, I prefer another way. More of a 'plug and chug' approach, this method just uses a prepackaged voltage regulator readily available from any number of different companies. Pretty much all you have to do is make sure that it will handle the current you are going to pull from it, and that you are supplying it with a voltage inside of its input range. One of the ones I built needed to have the voltage dropped down a bit further so I figured out the size of the resistor needed to put the input voltage inside the proper range. If you need to do this, just keep in mind the power dissipation.

Also, some regulators need a small capacitor in parallel with the output in order to stabilize it. The datasheet will mention if it requires one or not.

Comments

[raja26]

The regulator here looks like a NPN transistor (2N5294) that I have used for my joule thief, are they same?.

[KT Gadget]

NPN Transistors and voltage regulators are two separate electronic devices. NPNs act as a gate for larger currents to go through when the original output cannot handle the high currents while regulators step down the original voltage to a smaller voltage ( some are fixed voltages and some can be variable).

Like the 7805 regulator which is the 5 volt voltage regulator but there are other ones that can output a lower or higher voltage, but the input voltage has to be higher than the output.

[raja26]

Thanks, but actually I have typed it by mistake.

[pro2xy]

how do you calculate the voltage drop across a resistor?
V=IR??????? But when you cant predict the current???

[KT Gadget]

Take this equation: (original voltage in - the new voltage after the resistor) = (the current through the resistor) * (the resistor value in ohms)

[Mudbud]

you might want to add a heatsink in with the regulator.
 

[Mudbud]

esspecially if your going to use it allot and work it hard. it lengthens its life span

[sara majble]

I want to aske this expremenit have data?