Power supply question

Thread Starter

Talguy

Joined Aug 17, 2009
14
I'm working on building a power supply for my first project. My question is I need three voltage outputs 3.3, 5 and 12 volts to power my pic and peripherials, so long story short can I use a voltage regulator to get 12v and voltage dividers off the 12v to get the two other outputs

Evan
 
This might help you:



It depends on the current of each rail, but I would use a 7812 for the 12V rail and a 7805 for the 5V and any old 3V reg for the 3.3V.

Make sure your heat is less than 0.5W to keep everything from cooking. heat can be worked out from: (Input voltage - output voltage) x load current

Bill Naylor Electronic kits for Education and Fun
 
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jj_alukkas

Joined Jan 8, 2009
753
If you need light output per source like below 100mA, you can use a voltage divider with zenners from a 12v, but that is not feasible with minimum efficiency and hot divider resistors.

Better and standard way would be to use 7805 and 7812 and get the 3.3 with a voltage divider with zenner. If current is below 100mA, you can even use the 'L' series in a small TO-92 plastic case.
 
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