The search for a better DC-DC

**surfer6262** · 03-04-2002, 01:14 AM

In the on going search for a better DC power supply i thought of the following in the shower the other day.

1. Laptops can be pluged directly into a cig. lighter and then into the computer. So there is 12v going in

2. Laptops run on some of the same voltage as a full system. ie 12v, 5v

3. Laptop batteries! Why not place several laptop batteries under the floor boards and never have to worry about killing the car battery agian?

4. Laptop Powersupply, If the laptop can charge while in a car then why not just charge the batteries, or just use the laptop powersuppy to step the 12v, 5v

Im in no way an electrical engineer so i dont know exactly how to do it but I think i may have to try to do so!

**Raas** · 03-04-2002, 05:13 AM

Most laptops require 17->19vdc input to operate properly.
You cannot simply plug it into the cig.lighter.
There are some converters you can use for laptop.
They will give you say... 18v @ 2,5a, which is enough to charge it, and work with it.
But no laptop takes the filthy 12v in our cars unregulated.
There has to be some kind of circuit between your car's battery and the laptop.

Greetz

**THEMP3KID** · 03-04-2002, 06:22 AM

He He He, my old Black and White 486 did..

it died..

Nah, I just used a 12volt regulator to stop it from going over 12volts.. It worked for about 12hours, maybe.. Then stopped, dead!! after trashing it, I discovered that the CPU board had come loose, and there was nothing wrong with it.. hmm, ohh well..
Anyways, just saying that older laptops to work from lower input voltages, and this is what is used by some people.. (not me)

**Arby** · 03-04-2002, 10:52 AM

I have a "power supply" that came out of an old laptop. it takes 10-16V DC and converts it to 12V and 5V. It the size of a credit card and about 1/2" high.

all I have to do it get the 3.3V elsewhere, and I have a great supply for my FV24.

**CrazyLittle** · 03-04-2002, 02:42 PM

Originally posted by Arby
I have a "power supply" that came out of an old laptop. it takes 10-16V DC and converts it to 12V and 5V. It the size of a credit card and about 1/2" high.

all I have to do it get the 3.3V elsewhere, and I have a great supply for my FV24.

Well heck, all you need to do to get that is to wire up the 3.3v rail from the Sproggy design using one of the Maxim chips and you're setup to go.

**surfer6262** · 03-04-2002, 06:19 PM

AH HA!
I knew it! Arby, where did you get the PSU you speak of, any specs/info is great! Thx!

**Fosgate** · 03-04-2002, 08:43 PM

Guys what you are forgeting is the current...most laptop supplies only give out one or two amps on +5 and +12 rails...
With this sort of current you could only power up a laptop MB and laptop HD if you lucky...

**CrazyLittle** · 03-04-2002, 09:32 PM

That's true... I'm thinking in terms of the setup I'm building which will be pretty low consumption... I'm just doing a K6 mobo, LCD, HD and keypad/irman so I only need about 50-60w of power. Running a TFT/DVD or more toys would definately put me over the top.

**hornet** · 03-04-2002, 09:51 PM

Also, you would have to find a very old laptop, as the newer they get, the more intergrated they become. meaning that the power supply may not be seperate from the main system board.

**THEMP3KID** · 03-06-2002, 06:44 AM

Originally posted by Arby
I have a "power supply" that came out of an old laptop. it takes 10-16V DC and converts it to 12V and 5V. It the size of a credit card and about 1/2" high.

all I have to do it get the 3.3V elsewhere, and I have a great supply for my FV24.

Any idea of how much power it will give you?? wouldn't be more than a few amps on the 12volts, like 1.5ish.. and the 5volt wouldn't be more than about 3amps??

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