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-"izzi4" <
[email protected]> skrev i melding
--> Hello, i'm looking to put together a 12v 3amp power supply. Can i
-parallel
-> multiple regulators to add up to 3 amps or will this not work? Any other
-> simple suggestions to get this working?
-To let a power-transistor take most of the load:
That's one way to go. You size R1 so that the transistor
starts to conduct (Vbe of 0.6V) when the current across the small regulator
rises to a set point (say 200ma for a standard 1A 78XX part).
So using Ohm's Law:
R = V/I = .600V/.200A = 3 ohms
As the current demands of the load increases the small regulator will
cause more current to be drawn across the pass transistor.
Also note in the modified version below, there is a 7812 instead of a 7805.
BAJ
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- .--------- --------------.
- | \ v |
- | --- |
- | | |
- | | ____ |
- V_in | ___ | | | | V_out
- o-----o-|R1_|----o----|7812|-----o--------o
- |____|
- |
- |
- |
- ===
- GND
-(created by AACircuit v1.28 beta 10/06/04
www.tech-chat.de)
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