Need more 5v....

sq_geek · 05-12-2004, 11:26 PM

With my new setup, I am going to have to power:

* Slimline DVD (+5v, right?)
* USB 4-Port Hub (+5v)
* USB IDE Adapter (+5v, or does it power off USB bus?)

Plus the stuff in my PC already.

Assuming my PC's PSU's 5v rail is maxed just for powering my motherboard and laptop Hard Disk, I need more 5v I think.. How do I go about doing this? I'm scared to put too much draw on my 55w DC-DC PSU (Morex Cubid 2799 Case/PSU)..

Any ideas?

Can I pull it directly off of my ITPS (12v output) and use some kind of circuitry to drop it down to 5v??

Or will the 55w DC-DC be enough? After all, I won't be using my DVD player and USB Touchscreen (uses USB hub) at the same time very often..

Thanks!

darkhalo · 05-12-2004, 11:43 PM

dude thats why you just use an inverter

pip · 05-13-2004, 12:12 AM

Get a second dc-dc power supply?

sq_geek · 05-13-2004, 12:24 AM

No inverter, thanks..

Hmmm, 2nd DC-DC, I hadn't actually thought about that.. interesting...

Do you think this is too much load for my current DC-DC, then?

Squid · 05-13-2004, 12:34 AM

I have the same devices as you... but I'm running a laptop in my truck...
and I had to make my own 5 volt dc-dc power supplies. The load on my one
supply is a tad over .6 amps.. and thats powering a slotload dvd player... a
usb2.0 hub which is then powering a dlink radio, usb2ide adapter, lilliput
touchscreen, and deluo gps.

That .6 amps comes out to about 3 Watts of power if my brain remembers right...
as far as what ur pc is pulling.. I have no clue.. but adding up ur watts will tell u if
your overloading your ps.

bgoodman · 05-13-2004, 12:37 AM

might want to pickup a keypower dc-dc atx supply instead.

jusatry · 05-13-2004, 12:38 AM

add up the "factory reccomended" amperages on the 5V devices to get an idea of how much you are using/need. I would just buy a cheap pw60 or something and hack it up. you could probably come up on one in the FS forum here.....

i was wondering the same thing about circuitry though....ill bet someone here could tell us how to use voltage regulators to build a REALLY cheap 5v converter (for those of us with trunkmounted PCs and slimlines/hubs upfront, too)

EDIT apparently im a slow typist - squid beat me too it. squid - how did you make your own? for those of us who are not already electonically inclined pelase

Bgoodman: good call on the keypower....that arise you posted about works well too (i have one), and it is only $79!

sq_geek · 05-13-2004, 12:59 AM

But how do I figure out what the power needed for each of these is?? It doesn't say it anywhere that I could find:

* 7" StarVision Touchscreen - USB
* 4-Port USB 2.0 Hub
* Matsu****a SR-8185-C
* GPS eventually
* USB Thumb Drive eventually
* USB Game Pad eventually
* Via M10000 w/Audigy 2zs sound card

I found:

* 40GB Laptop HD needs 2.7 @ +5v

Squid · 05-13-2004, 01:25 AM

Here it is..... I'm a Mechanical Engineer.. not Electrical... so I just stole
this from the typical applications sheet of the IC

The circuit is super stable... only downside is it creates a fair amount of
heat. I used 5 amp heatsinks on the IC's but still too hot to touch.
So I used thermal paste and bolted to an alum radioshack box also.
Still hot... but u can touch it. Just have to have them mounted with space
around them.

I got all the parts from Jameco

LM350T - IC (used in place of LM150) p/n: 23940
Heat Sink - p/n: 164734
Diode - p/n: 76961
240 Ohm Resistor - p/n: 30568
.1uF Cap - p/n: 33486
10uF Cap - p/n: 10882
1uF Cap - p/n: 154860
5k potentiometer - p/n: 95450

You use the pot to set the output voltage... I found that for 5.15 volts I
needed 750 Ohm resistor p/n: 31561, but I'd recommend getting the pot
also to test for your needs.

Total Price: $10.93 (but most parts are qty 10... except IC.. 1.75 each.. so
add 1.75 for every one after the initial money up to 10 ps)

My final results:

The second one I did was alot prettier... since I worked out all the bugs on
mounting the circuit inside the case. But I have no internal pics of 2nd one!
And these pics are before the mounds of hot-glue to support the board

Hope that helps some!

Squid

jusatry · 05-13-2004, 01:26 AM

any USB device that does not need external power should be no more than .25 amps (could be .5, not sure). the hub/sound card should have the rating on them. if not, check their AC adaptors. whatever the amp limit is should be what you count for that.

so all we have left is the hub, assuming its externally powered, the DVD drive (should be on it), the M10000, and the audigy. check via's site/epia's site or manual about the mobo, and check the power adptors rating for the audigy.

EDIT: our posts keep crossing on the internet - damn you're fast

squid, how much were all the parts? you said it puts out .6 amps.....my slim dvd drive is rated @ 1.8 amps.....is that WAY overrated, or did i mis-understand what you were saying?

.....maybe i could build two of them

....

Squid · 05-13-2004, 01:34 AM

Oh.. sorry about that.. yea.. when the cd/dvd spools up.. it pulls 1.3 amps.. sometimes 1.5... but we're talking split second...
maybe .5 to 3/4 of a second... at normal spinning speed it was only .3 amps
if I remember correctly.. maybe lower.

These circuits are good for about 2 amps... so I figured with the .6 of the hub and
all the other parts mentioned earlier... it was fine....

And I built another for the audigy 2 nx in the back.. it pulls .83 amps constantly when
on.. no variation.

ps... I added price to above post.. sorry

jusatry · 05-13-2004, 02:01 AM

SAWEEET!!! Next project

so for every extra IC i get i can make another board - ie after the first one it is $1.75 a piece to make these bad boys?

awesome

1 question - im not too good at schemo's yet, are the red and black wires the 12V in and the 2 black wires the 5v out?

Squid · 05-13-2004, 02:13 AM

I updated the schematic with the +12 and +5....
Yes on my build... the heavier wires are the ones to the car.. the smaller black
wires is the audigy plug i just hacked off

As far as the price.. yea... most of the small parts are 10 or more pieces...
Can't recall right now.. buy IC is 1 per as are the heatsinks I think....
So yea.. for a few bucks you can build one after the initial parts buy.

Get a small prototyping breadboard.... I always prove all my circuits out before I
waste time soldering...

jusatry · 05-13-2004, 02:41 AM

but soldering is so fun

thanks so much for the advice - squid, you're the man!

Defiler · 05-13-2004, 09:45 AM

Quote: Originally Posted by darkhalo

dude thats why you just use an inverter

AMEN BRUTHA!!!!