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It is difficult to get the regulators to share the output currentHello, 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?
This one is easier to use.Better to buy a higher current device like an LM323 and modify it to
provide 12 volts.
http://cache.national.com/ds/LM/LM123.pdf
John Popelish wrote:
Better to buy a higher current device like an LM323 and modify it to
provide 12 volts.
http://cache.national.com/ds/LM/LM123.pdf
This one is easier to use.
http://cache.national.com/ds/LM/LM150.pdf
--
John Popelish
Yeah. Digikey socks you with a $5 surcharge for an under $25 order,any idea of where to get these inexpensivly? I always get stuck paying
double for shipping and for only one component it seems dumb.
To let a power-transistor take most of the load:Hello, i'm looking to put together a 12v 3amp power supply. Can i
parallel
multiple regulators to add up to 3 amps or will this not work? Any other
simple suggestions to get this working?
Hello, i'm looking to put together a 12v 3amp power supply. Can i parallel
multiple regulators to add up to 3 amps or will this not work? Any other
simple suggestions to get this working?
Maybe it is just the schematic is hard to read, but the transistor should be aIn article <ck5l7k$d5l$1@services.kq.no>,
Geir Klemetsen <ugyldig@adresse.no> wrote:
-
-"izzi4" <news@rkremser.endjunk.com> skrev i melding
-news:1097205711.wtEIT1cgtBiWOI0WRvgWiA@teranews...
-> 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
-
- .--------- --------------.
- | \ 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)
-
It works if you use equilizing resistors as if you were paralleling BJTs,i wouldn't do that.
because the chance you will get them to share the load equally is
1:1000 and one them will end up doing most of the work and the 2
others just loafing along.