power suply

cennar · Post by **cennar** » Mon Jan 24, 2005 6:45 pm

ok i need my 7.2 2amp battry to out put 3.3 5 and 12 volts, i have a bad habit of being compleatly useless with power suplys so im asking here before i do any more rescreach on this one.

HK-47 · Post by **HK-47** » Mon Jan 24, 2005 6:46 pm

Im pretty sure dc-dc converers have something to do with it...

Post by **gannon** » Mon Jan 24, 2005 6:47 pm

I'm not even sure if a boosting dc-dc converter can convert 7.2V into 12V efficiently.

SNESguy · Post by **SNESguy** » Mon Jan 24, 2005 7:11 pm

Let me tell you something about buck/boost converters:

-They are not good for portable application, because your current on the input will be double/triple the rating of your initial current on the 12v line.

-Example: if your 12v requirement is 300mA, (3.6 watts) expect your current on the 7.2v side to be something around 500mA or HIGHER.

-Its best to start at the highest voltage(12v), then go down to 5v and 3.3v.

SNESguy · Post by **SNESguy** » Mon Jan 24, 2005 7:13 pm

What kind of application do you want to use it for?
If you specify, we can probably help you better.

JackFrost22 · Post by **JackFrost22** » Mon Jan 24, 2005 7:18 pm

Post by **gannon** » Mon Jan 24, 2005 7:18 pm

From the voltages he listed I'm assuming he's using them for a DCp

SNESguy · Post by **SNESguy** » Mon Jan 24, 2005 7:26 pm

Then I suggest using a 12v battery for best efficiency, unless it has an onboard 7805 like the N64.
Then you could use regular 7.2v

Post by **gannon** » Mon Jan 24, 2005 7:31 pm

I would use a mini-itx power supply. Not only are they one of the cheapest/efficient dc-dc converters, they output 3.3V, 5V, and 12V using a 11V battery.

HK-47 · Post by **HK-47** » Mon Jan 24, 2005 8:01 pm

http://www.mini-itx.com/store/?c=10

cennar · Post by **cennar** » Mon Jan 24, 2005 8:24 pm

gannon wrote:From the voltages he listed I'm assuming he's using them for a DCp

i also asume that too there... and thanks for the help so far *im realy bad and powersuplys*

also what did brave portables guy use there he was using 7.2s like mine (plus an extra amp) and i dont mind adding an other 7.2 if needed.

Post by **gannon** » Mon Jan 24, 2005 9:19 pm

I thought that he used 2 7.2V batteries in series.

Guest · Post by **Guest** » Mon Jan 24, 2005 9:52 pm

gannon wrote:I thought that he used 2 7.2V batteries in series.

I agree this is what I would do.

mindstein · Post by **mindstein** » Mon Jan 24, 2005 9:58 pm

sorry that was me I forgot to log in

I used 2 voltage converters in my VCSp (one for the LCD and one for the VCP. Looks Like you will need several.

Just make sure to isolate the grounds on each and they should work fine.

cennar · Post by **cennar** » Mon Jan 24, 2005 10:18 pm

vcsp we're talkin dcp here...

ok tell me exactly what the guy who made the first dreamcast portable used as a power suply (i want every thing)