Building a DC-DC power supply

**mariushm** · 07-22-2012, 09:44 PM

Re: Building a DC-DC power supply

You won't be able to power anything straight from car's 12v, at least without some serious filtering... That voltage will oscillate between 9-15v or something like that, when you start the car, when you break, depending on the weather conditions (starting car during winter etc).

power supplies...

http://www.jonnyguru.com/modules.php...Story&reid=207

BUT... not really wise to power it from car's 12v - as you can see in the roundup above, some of those don't really filter the 12v and the one that does (the winner) is designed for actual car usage and works on wide voltage range but had very poor 12v output (2-4A if I remember correctly) if input was not within a voltage range.

That board in the other post is heavy on the 12v, and the p4 cpus are also power hungry... might wanna use that board for a home tv kind of build and spend 60$ on something like this:

http://www.newegg.com/Product/Produc...82E16813157324

The e-240 has a 18w tdp so the whole board is probably gonna use less than 30 watts so one of those picoPSU may have enough juice to power the lcd as well.

This 25$ one might be enough (80watter): http://www.mini-box.com/picoPSU-80

A quality 150-300w inverter may make more sense in the end if you want to reuse lots of parts you already have around.

ps. -12v and -5v are no longer required for modern boards. -12v is currently optional in atx 2.something, most new boards (including probably the one i linked to) don't use it, as they don't have com/serial ports anymore. Your CFI board, being the industrial kind, most probably still needs them... another negative point for it.

**shovenose** · 07-22-2012, 10:22 PM

Re: Building a DC-DC power supply

Alright. Would that AMD E-240 be faster than the Pentium 4?

Edit: would it be smarter just to use my laptop? Core i5 Quad 2.3GHz, 4GB RAM, 64GB SSD, Windows 7 Ultimate. Wouldn't be as fun or cool though

How can I add touchscreen to my Asus laptop?

**mariushm** · 07-23-2012, 05:53 AM

Re: Building a DC-DC power supply

http://cpubenchmark.net/cpu_list.php :

AMD E-240 297 points

Intel Pentium 4 1.90GHz 229
Intel Pentium 4 2.00GHz 247
Intel Pentium 4 2.20GHz 278
Intel Pentium 4 2.26GHz 282
Intel Pentium 4 2.40GHz 313

So in theory it would match with a p4 2.4 ghz. But remember, you're actually pairing it with ddr3 ram AND the integrated video card is a monster compared to whatever could be inside that old board so it will FEEL much faster. The integrated video card can do youtube videos, hd videos, most games at low resolutions, whatever you throw at it. Yeah, on a 8" lcd screen it doesn't matter much but still..

Hmm... No... that laptop, no. Too powerful for what you probably need in the car and then you'd have to worry that maybe one day you'll forget to take it out and someone's gonna steal it.

Laptops do have the advantage that they take one voltage in so it's potentially easy to adapt that to work in a car environment but you'd still need to convert the unreliable 12v to 12-19v the laptop would need. There's also the second advange that you flip open the screen and have keyboard under it.
Maybe if you find at Goodwill or whatever stores you have around an eepc or something similar it would be worth it.

If you decide to go this route, there are converters such as this one which does 9.6-17v to 19v in case your laptop is 19v based: http://www.bixnet.com/12vdcto19vdc.html

**shovenose** · 07-23-2012, 05:10 PM

Re: Building a DC-DC power supply

Cool, but one issue: I still need to buy DDR3 then

and a SATA SSD
and a case
but I might still do it because it's a good idea

**ben7** · 07-24-2012, 04:49 AM

Re: Building a DC-DC power supply

You could easily build some voltage regulator circuits with bucking-SMPS chips.

But what are your power requirements on the voltage rails?

Building a DC-DC power supply

Building a DC-DC power supply

Comment

Comment

Comment

Comment

Comment

Related Topics