Powering a computer without inverting. - Electronic Circuits Projects Diagrams Free

Darfk · 29th October 2007, 04:11 AM

I know this is possible I just need some help/advice with it.

I want to power my computer from my 12 volt car battery. I do not want to use an inverter. I do not need to use a monitor just a motherboard (w/CPU,RAM,GFX card), hard drive, and a sound card. The CPU is an old AMD Socket7 1.63GHz. Hard drive is a 80GB Seagate.
Anyway I want to know if I can regulate voltages accurately and efficiently enough to keep my system stable with several LM337s and LM317s (negative and positive voltage regulators)? At first I only want it running off a battery ie. no car attached.

Can anyone suggest a better regulator for my application?
Is there an existing project that solves my problem?
Or is it more affordable/easy to invert?

Help would be very appreciated.

kchriste · 29th October 2007, 04:30 AM

Quote:

Or is it more affordable/easy to invert?

You don't have your location filled in, but where I live you can buy a 800 watt inverter for under $100 CDN. This is the method I would use myself. Linear regulators, such as the LM317 etc, would generate too much heat and you would still have to "invert" for the -12V line though your motherboard may not use it for anything other than serial IO.

Darfk · 29th October 2007, 04:51 AM

I have been looking around for power inverters and they are fair expensive about $180AUD for a modified sine wave @ 600W. I can't afford this at them moment as I am a student

I am aware that I will have to use several regulators to spread the load across.
And I am under impression that the LM337 outputs a negative voltage using a positive input. <<-- correct me if I am wrong.

mvs sarma · 29th October 2007, 05:07 AM

If you try to generate +5V from 12V battery with HiGH current demand, you will be wasting lot of power as heat.

once the battery -ve has been used as common for the PC, you will not be able to to use LM337 etc for generating -ve voltages (-5 and -12V) unless the switch mode techniques are used.

I presume thatyou only wanted to to avoid going to 12V DC to 230V AC conversion!! Perhaps you areaiming for a DC-DC converter with input 12V battery (13.8 to 10.8 on the lower side) and with normal outputs that are required for a PC mother board and HDD etc. It is possible and there are some manufacturers supplying such DC-DC converters.

One such psu is M2-ATX manufactured by www.mini-box.com

By such a method you may reduce losses that arise due to double conversion.

pasanlaksiri · 29th October 2007, 05:33 AM

R u trying to make a CAR PC. Awesome

Ambient · 29th October 2007, 05:38 AM

Great website man! They have some really nice stuff.

mvs sarma · 29th October 2007, 05:39 AM

Quote:

Originally Posted by Darfk

I know this is possible I just need some help/advice with it.

I want to power my computer from my 12 volt car battery. I do not want to use an inverter. .............................
Can anyone suggest a better regulator for my application?
Is there an existing project that solves my problem?
Or is it more affordable/easy to invert?

Help would be very appreciated.

Try LM25 series switching regulators . you may google for details or datasheets at www.alldatasheet.com

Gordz · 29th October 2007, 06:35 AM

You need -12v and -5v for most PC's so you will have to invert somewhere along the line and the current required for the +5 will be pretty high. The Simple Switcher series from National Semiconductor will be good for this project as they will allow 'simple' inversion as some can be configured as buck/boost/invert.

**Nigel Goodwin** · 29th October 2007, 09:28 AM

Quote:

Originally Posted by Darfk

I have been looking around for power inverters and they are fair expensive about $180AUD for a modified sine wave @ 600W. I can't afford this at them moment as I am a student

Remarkably good value, if you can't afford it you probably can't afford to build anything either!.

Quote:

I am aware that I will have to use several regulators to spread the load across.
And I am under impression that the LM337 outputs a negative voltage using a positive input. <<-- correct me if I am wrong.

Sorry, but you are completely wrong, it's a negative regulator for a negative supply.

Super_voip · 29th October 2007, 09:34 AM

http://www.mini-box.com/s.nl/sc.8/category.13/.f is the first site on a google search

ericgibbs · 29th October 2007, 09:37 AM

Quote:

Originally Posted by pasanlaksiri

R u trying to make a CAR PC. Awesome

Hi Pasan,
Its already been done,, it called a 'Laptop'!

ericgibbs · 29th October 2007, 09:46 AM

Quote:

Originally Posted by Darfk

I know this is possible I just need some help/advice with it.

I want to power my computer from my 12 volt car battery. I do not want to use an inverter. I do not need to use a monitor just a motherboard At first I only want it running off a battery ie. no car attached.

If you used a 2nd 12V battery, you could get the +12v/5V and -12v/-5v supplies required.
The negative supply requires less current than the positive supplies to your motherboard etc..

Without using SMP'S, a linear +5V would not be efficient.
Also the +12v psu for the PC, from a 12v battery would not be regulated.

How much current on each power rail, is the PC going to require?

IMO, a SMPS would be the best way to go.

mvs sarma · 29th October 2007, 10:55 AM

Simple concept Eric, now he should have two chargers for the battery maintenance, I fear.

ericgibbs · 29th October 2007, 11:23 AM

Quote:

Originally Posted by mvs sarma

Simple concept Eric, now he should have two chargers for the battery maintenance, I fear.

Hi Sarma,
As they say 'there's no such thing as a free lunch'

Thats why man invented the SMPS and mains invertor!

pasanlaksiri · 29th October 2007, 04:50 PM

Quote:

Originally Posted by ericgibbs

Hi Pasan,
Its already been done,, it called a 'Laptop'!

. But where is da fun

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29th October 2007, 04:11 AM	(permalink)
Darfk	Powering a computer without inverting. I know this is possible I just need some help/advice with it. I want to power my computer from my 12 volt car battery. I do not want to use an inverter. I do not need to use a monitor just a motherboard (w/CPU,RAM,GFX card), hard drive, and a sound card. The CPU is an old AMD Socket7 1.63GHz. Hard drive is a 80GB Seagate. Anyway I want to know if I can regulate voltages accurately and efficiently enough to keep my system stable with several LM337s and LM317s (negative and positive voltage regulators)? At first I only want it running off a battery ie. no car attached. Can anyone suggest a better regulator for my application? Is there an existing project that solves my problem? Or is it more affordable/easy to invert? Help would be very appreciated.

29th October 2007, 04:51 AM	(permalink)
Darfk	I have been looking around for power inverters and they are fair expensive about $180AUD for a modified sine wave @ 600W. I can't afford this at them moment as I am a student I am aware that I will have to use several regulators to spread the load across. And I am under impression that the LM337 outputs a negative voltage using a positive input. <<-- correct me if I am wrong.

29th October 2007, 05:07 AM	(permalink)
mvs sarma	If you try to generate +5V from 12V battery with HiGH current demand, you will be wasting lot of power as heat. once the battery -ve has been used as common for the PC, you will not be able to to use LM337 etc for generating -ve voltages (-5 and -12V) unless the switch mode techniques are used. I presume thatyou only wanted to to avoid going to 12V DC to 230V AC conversion!! Perhaps you areaiming for a DC-DC converter with input 12V battery (13.8 to 10.8 on the lower side) and with normal outputs that are required for a PC mother board and HDD etc. It is possible and there are some manufacturers supplying such DC-DC converters. One such psu is M2-ATX manufactured by www.mini-box.com By such a method you may reduce losses that arise due to double conversion. __________________ Regards, Sarma. Last edited by mvs sarma; 29th October 2007 at 05:15 AM.

29th October 2007, 05:33 AM	(permalink)
pasanlaksiri	R u trying to make a CAR PC. Awesome __________________ Digital Voltmeter PIC16F877 Audio CD Player My home made 2.1 System Nokia 3310 Lcd & Pic12F629 3 channel IR remote Controller Project using 12F Pic Pasan...

29th October 2007, 05:38 AM	(permalink)
Ambient	Great website man! They have some really nice stuff.

29th October 2007, 06:35 AM	(permalink)
Gordz	You need -12v and -5v for most PC's so you will have to invert somewhere along the line and the current required for the +5 will be pretty high. The Simple Switcher series from National Semiconductor will be good for this project as they will allow 'simple' inversion as some can be configured as buck/boost/invert.

29th October 2007, 09:34 AM	(permalink)
Super_voip	http://www.mini-box.com/s.nl/sc.8/category.13/.f is the first site on a google search

29th October 2007, 10:55 AM	(permalink)
mvs sarma	Simple concept Eric, now he should have two chargers for the battery maintenance, I fear. __________________ Regards, Sarma.