Use a 7809 Voltage regulator

Maybe a little heatsink should be used also, there will be generated 3W of
heat


Brian

The 7809 might not work well with only 3v of drop. Look for a low dropout
type regulator. They can work with lower in-out voltage difference. For
3 watts dissipation, look for a 10 deg C per watt or less heat sink.

"Lawrence Lucier" wrote in message
...

Howdy all..... :-)

Has anyone a suggestion for a 3 terminal voltage regulator that
will take 12vdc input and output 9vdc @ 1A?

Any suggestions would be much appreciated...thanks! :-)

Brian Lund wrote:

Use a 7809 Voltage regulator


Maybe a little heatsink should be used also, there will be generated 3W of
heat


Brian


there is no 7809
your choice is 7805, 7808, 7812
rw

there is no 7809

"there is no spoon" - sorry i had to do the matrix

your choice is 7805, 7808, 7812

The datasheet from SGS Thomson says that they produce the 78 series
regulator in the following voltages;
5, 5.2, 6, 8, 8.5, 9, 12, 15, 18 and 24V


Furthermore i have been working with the 7809 and others that you didn't
mention so i am sure they exist... Try google next time!


Brian Lund

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The LM317, not a very good choice;

Not Low Dropout, requires a three volt difference in i/o voltages,
however it does handle around 1.5A. Try this part #: KA278R09TU, it can
be ordered from Fairchild Semi or any one of their agents, and the good
news, is they offer free samples of it, so you can probably hook
yourself up with 5 - 10 for free . Dropout is rated at "below 0.5V"
and can handle around 2A -- This regulator has various functions such as
peak current protection, thermal shut down, overvoltage protection and
output disable function.

Datasheet: http://www.fairchildsemi.com/ds/KA/KA278R09.pdf
Product Page: http://www.fairchildsemi.com/pf/KA/KA278R09.html

wpa wrote:

| use LM317 with 2 resistors calculated for 9V.
|
| "Lawrence Lucier" schreef in bericht
| ...
|
|Howdy all..... :-)
|
|Has anyone a suggestion for a 3 terminal voltage regulator that
|will take 12vdc input and output 9vdc @ 1A?
|
|Any suggestions would be much appreciated...thanks! :-)
|
|
|

- --

Regards,

Sean Coyle
President
Greenroom Networx
Ph: 604.941.7832
Fx: 604.941.7803

"Working to create teleports for economic and business development,
Intelligent City, information and communications technology"
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I see all these posts wanting to go from 12v to 9vdv

I would just use 2 resistors to split the potential difference? What am I
missing why are "LM317" etc a better chocice?


"@ spam]grnetx.com" ""sean.coyle[no \"@ spam]grnetx.com" wrote in message
. ca...
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The LM317, not a very good choice;

Not Low Dropout, requires a three volt difference in i/o voltages,
however it does handle around 1.5A. Try this part #: KA278R09TU, it can
be ordered from Fairchild Semi or any one of their agents, and the good
news, is they offer free samples of it, so you can probably hook
yourself up with 5 - 10 for free . Dropout is rated at "below 0.5V"
and can handle around 2A -- This regulator has various functions such as
peak current protection, thermal shut down, overvoltage protection and
output disable function.

Datasheet: http://www.fairchildsemi.com/ds/KA/KA278R09.pdf
Product Page: http://www.fairchildsemi.com/pf/KA/KA278R09.html

Jason ,

Firstly , 2 resistors are a waste of watts , secondly any appreciable
current draw at the split will change the voltage at the split .

If I want 9v from 12v , I just use one of my 100 5v regs i got free
off parts boards---I put some cheap generic diodes in the reference
leg of the reg ( they are 7805s good for at least 1 amp .

Am LM317 to me is only worth the bother and cost$ for Variable Voltage
output power supplies . I think its only good for about 1 or so amp
anyway , if I need more current I use a power junction transistor PNP
, NPN whatever works .

tim CET MD-238

"Jason" wrote in message ...
I see all these posts wanting to go from 12v to 9vdv

I would just use 2 resistors to split the potential difference? What am I
missing why are "LM317" etc a better chocice?


"@ spam]grnetx.com" ""sean.coyle[no \"@ spam]grnetx.com" wrote in message
. ca...
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

The LM317, not a very good choice;

Not Low Dropout, requires a three volt difference in i/o voltages,
however it does handle around 1.5A. Try this part #: KA278R09TU, it can
be ordered from Fairchild Semi or any one of their agents, and the good
news, is they offer free samples of it, so you can probably hook
yourself up with 5 - 10 for free . Dropout is rated at "below 0.5V"
and can handle around 2A -- This regulator has various functions such as
peak current protection, thermal shut down, overvoltage protection and
output disable function.

Datasheet: http://www.fairchildsemi.com/ds/KA/KA278R09.pdf
Product Page: http://www.fairchildsemi.com/pf/KA/KA278R09.html

Yes, 7809s are the easiest , but not cheap$ or easily buyable...except
MABE the high$ shack . Definately use a heat sink it approaches hot to
touch when running under full load !!! ( whatever reg or xsistor you
use )

tim

"Brian Lund" wrote in message . dk...
Use a 7809 Voltage regulator

Maybe a little heatsink should be used also, there will be generated 3W of
heat


Brian