In need of circuit: 12V Car Battery - > 22V 2A Laptop - Electronic Circuits Projects Diagrams Free

Aldo · 25th July 2003, 04:42 AM

Hi,
Does anyone know where to get a circuit diagram of a DC DC converter,
I ve been looking for this for several weeks, without any result.
I have a laptop that draws lots of amps, and I am trying to use it while
working out of home (its litium battery is death :cry: )
Thanks in advance

Al

john1 · 25th July 2003, 05:26 AM

Hi Aldo,

Sierra Solar Systems do a 12 to 24 volt step up
converter for $54

http://www.pyacht.net/cgi-local/Soft....htm?E+scstore
These are pricey, four to six hundred somethings,
probably dollars.

http://www.powerstream.com/DC_PC.htm
these are all over a hundred dollars.

just put this:
"12 to 24" volt
into google, 1710 hits

If you want to build your own, see:
http://www.acs.comcen.com.au/12_24reg.html

A 12 to 24 volt unit which was made for a solar panel,
but looks about right for a laptop.

Best of luck, John

stevez · 25th July 2003, 12:49 PM

Aldo - I was surfing thru the National Semiconductor website and stumbled on to their design area. It would appear that they have a way to help select a device and from the applications guide there are schematic diagrams. I was left with the impression that for many common applications the on-line design center would literally give you the values and sources for all of the critical parts. I was pleasantly surprised that with one design (similar to your needs) that the most critical part was the inductor and it was a 2 dollar item.

Aldo · 25th July 2003, 04:24 PM

Hi guys,
thanks for your replies,
I ve been looking at the diagram that you John provides,
it looks not so difficult, I m gonna search for the IC the author
uses,
Thanks you Stevez for your help, I m gonna take a look on that
web site,
Thanks a lot guys,
Have a great day

Aldo

Jaw174 · 27th July 2003, 03:42 PM

HAHAH i dont know HOW manny times i see this on forums all over... and everyone edns up spending way to much time, money, and headaches trying to figure itu out! and it can cost you somewhere between 20-40 dollars! not $600 dollars. just get a simple DC-AC inverter, then just use you rAC adapter in the car.. i got my 60 watt inverter at Walmart for just $22 dollars. my friend got a 300 watt for a measly $60 dollars at a computer fair... its alot cheaper, and has WAY more uses! (IE radios and small Tv's, full computers and LCD monitors..ect..)

john1 · 27th July 2003, 05:15 PM

Hi Jaw174,

That sounds like a very practical suggestion.
I have a small inverter,
but i have never tried it on any computer stuff,
ive always thought the output was a bit too rough.

As for running it through the laptops charger-pack
or AC-adapter that comes with the laptop,
i am a little wary of doing that.

I may put a dummy load on the adapter, to see how
it behaves from the inverter.

Certainly worth checking out,

Cheers, John

Sebi · 27th July 2003, 07:46 PM

This is a possible solution...

TheDisturbedOne · 27th July 2003, 10:20 PM

Isn't that problem related to sine waves or something? (I have no clue thats why I'm asking)

john1 · 28th July 2003, 01:26 AM

Hi there TheDisturbedOne,

Yes, its that sort of thing.
An inverter (typically)gives a square wave into a transformer
from a battery, and the transformer steps up to mains voltage.

Its ok for lots of stuff, but it can upset some electronic goods.

Maybe they do units now that give better waveforms.

Regards, John

Klaus · 28th July 2003, 03:50 AM

I use an inverter to power the laptop from 12V (boat) batteries. It is about the simplest solution for this application. The cheaper inverters (like my 150W unit) output what's called a modified sine wave, it looks like a stepped square wave. Since this is fed into the laptop's mains power supply, which is usually of the switching variety, it is this and NOT the laptop that gets the modified sine wave. There appears to be no problem with my inverter to power the laptop's power supply. My laptop is a 18V unit, so it draws about 1/3rd more Amps than stated on its power supply from the boats 12V batteries.
Klaus

Aldo · 29th July 2003, 05:21 AM

Hi ,
you guys are posting very good ideas,
porbably an inverter is not that expensive, but
what 's going to happen if I like to keep the laptop on while
turning off and on the engine?
I know there is always some surge from the alternator,
Is there any way to eliminate most of the surges and provide safe
operation to the laptop even with frequent on and offs?
Thanks a lot 8)

Aldo

Sebi · 29th July 2003, 06:37 AM

I'm sure, no need inverter. If You build the boost converter ( my previous post ) with serial diode and high capacitor on input, it will work.

Jaw174 · 30th July 2003, 03:21 AM

why would you spend the time on a circuit if u can get an inverter much faster, as well as cheaper. ypu dont need to worry about the sine wave issue, as its going into another transformer to the laptop, which is further smoothed out by the capacitors in the AC-adaper. if you are worried about back surges and the like, most if not all inverters are prepared to handle that, as my cheap one even is, but if you witsh, you could add a surge supressor/ UPS and further lengthen the ability to supress teh minute surges that MAY occur. i have been using my inverter for 2 years with several cars, in a 97' mercury villager, an 87' honda civic, and a 74' ford pickup. iv had No problems whatsoever in any of these vehicles, and neither should you... and if you DO then its probably because you are exceding the wattage ratings, if ur using like a oven or somethijng, not becasue of surges of not the correct wave forms. AC out of the wall isnt always perfect either, the wave forms can be "deformed" as well. i know my friend lives in an old are of town and needs this box thing hooked up to his monitor to reconvert the signal from whatever it is to a since/square wave otherwise he gets lots of "fuzz".
USE AN INVERTER!

Aldo · 30th July 2003, 03:46 AM

Hi guys,
I can see that the circuit posted by Sebi is not that difficult to build,
the problem is where I live, I don't have any electronics shop to go and buy the components, even the IC ( I think is a National Semicond) this one is not expensive, but like Jaw says, yeah, is faster to get one from Walmart,
I m gonna take a look there,
now I have another question, but it s related to the laptop lcd,
I m gonna post it in the right forum,
Thanks a lot guys, very useful ideas....and don't get mad!! be :wink: :lol:

Aldo

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25th July 2003, 04:42 AM	(permalink)
Aldo	In need of circuit: 12V Car Battery - > 22V 2A Laptop Hi, Does anyone know where to get a circuit diagram of a DC DC converter, I ve been looking for this for several weeks, without any result. I have a laptop that draws lots of amps, and I am trying to use it while working out of home (its litium battery is death :cry: ) Thanks in advance Al

25th July 2003, 05:26 AM	(permalink)
john1	Hi Aldo, Sierra Solar Systems do a 12 to 24 volt step up converter for $54 http://www.pyacht.net/cgi-local/Soft....htm?E+scstore These are pricey, four to six hundred somethings, probably dollars. http://www.powerstream.com/DC_PC.htm these are all over a hundred dollars. just put this: "12 to 24" volt into google, 1710 hits If you want to build your own, see: http://www.acs.comcen.com.au/12_24reg.html A 12 to 24 volt unit which was made for a solar panel, but looks about right for a laptop. Best of luck, John

25th July 2003, 12:49 PM	(permalink)
stevez	Aldo - I was surfing thru the National Semiconductor website and stumbled on to their design area. It would appear that they have a way to help select a device and from the applications guide there are schematic diagrams. I was left with the impression that for many common applications the on-line design center would literally give you the values and sources for all of the critical parts. I was pleasantly surprised that with one design (similar to your needs) that the most critical part was the inductor and it was a 2 dollar item. __________________ stevez

25th July 2003, 04:24 PM	(permalink)
Aldo	Hi guys, thanks for your replies, I ve been looking at the diagram that you John provides, it looks not so difficult, I m gonna search for the IC the author uses, Thanks you Stevez for your help, I m gonna take a look on that web site, Thanks a lot guys, Have a great day Aldo

27th July 2003, 03:42 PM	(permalink)
Jaw174	HAHAH i dont know HOW manny times i see this on forums all over... and everyone edns up spending way to much time, money, and headaches trying to figure itu out! and it can cost you somewhere between 20-40 dollars! not $600 dollars. just get a simple DC-AC inverter, then just use you rAC adapter in the car.. i got my 60 watt inverter at Walmart for just $22 dollars. my friend got a 300 watt for a measly $60 dollars at a computer fair... its alot cheaper, and has WAY more uses! (IE radios and small Tv's, full computers and LCD monitors..ect..) __________________ Do no meddel in the affairs of dragons, for you are tasty and go good with ketchup.

27th July 2003, 05:15 PM	(permalink)
john1	Hi Jaw174, That sounds like a very practical suggestion. I have a small inverter, but i have never tried it on any computer stuff, ive always thought the output was a bit too rough. As for running it through the laptops charger-pack or AC-adapter that comes with the laptop, i am a little wary of doing that. I may put a dummy load on the adapter, to see how it behaves from the inverter. Certainly worth checking out, Cheers, John

27th July 2003, 10:20 PM	(permalink)
TheDisturbedOne	Isn't that problem related to sine waves or something? (I have no clue thats why I'm asking) __________________ IT IS I!

28th July 2003, 01:26 AM	(permalink)
john1	Hi there TheDisturbedOne, Yes, its that sort of thing. An inverter (typically)gives a square wave into a transformer from a battery, and the transformer steps up to mains voltage. Its ok for lots of stuff, but it can upset some electronic goods. Maybe they do units now that give better waveforms. Regards, John

28th July 2003, 03:50 AM	(permalink)
Klaus	I use an inverter to power the laptop from 12V (boat) batteries. It is about the simplest solution for this application. The cheaper inverters (like my 150W unit) output what's called a modified sine wave, it looks like a stepped square wave. Since this is fed into the laptop's mains power supply, which is usually of the switching variety, it is this and NOT the laptop that gets the modified sine wave. There appears to be no problem with my inverter to power the laptop's power supply. My laptop is a 18V unit, so it draws about 1/3rd more Amps than stated on its power supply from the boats 12V batteries. Klaus

29th July 2003, 05:21 AM	(permalink)
Aldo	Hi , you guys are posting very good ideas, porbably an inverter is not that expensive, but what 's going to happen if I like to keep the laptop on while turning off and on the engine? I know there is always some surge from the alternator, Is there any way to eliminate most of the surges and provide safe operation to the laptop even with frequent on and offs? Thanks a lot 8) Aldo

29th July 2003, 06:37 AM	(permalink)
Sebi	I'm sure, no need inverter. If You build the boost converter ( my previous post ) with serial diode and high capacitor on input, it will work.

30th July 2003, 03:21 AM	(permalink)
Jaw174	why would you spend the time on a circuit if u can get an inverter much faster, as well as cheaper. ypu dont need to worry about the sine wave issue, as its going into another transformer to the laptop, which is further smoothed out by the capacitors in the AC-adaper. if you are worried about back surges and the like, most if not all inverters are prepared to handle that, as my cheap one even is, but if you witsh, you could add a surge supressor/ UPS and further lengthen the ability to supress teh minute surges that MAY occur. i have been using my inverter for 2 years with several cars, in a 97' mercury villager, an 87' honda civic, and a 74' ford pickup. iv had No problems whatsoever in any of these vehicles, and neither should you... and if you DO then its probably because you are exceding the wattage ratings, if ur using like a oven or somethijng, not becasue of surges of not the correct wave forms. AC out of the wall isnt always perfect either, the wave forms can be "deformed" as well. i know my friend lives in an old are of town and needs this box thing hooked up to his monitor to reconvert the signal from whatever it is to a since/square wave otherwise he gets lots of "fuzz". USE AN INVERTER! __________________ Do no meddel in the affairs of dragons, for you are tasty and go good with ketchup.

30th July 2003, 03:46 AM	(permalink)
Aldo	Hi guys, I can see that the circuit posted by Sebi is not that difficult to build, the problem is where I live, I don't have any electronics shop to go and buy the components, even the IC ( I think is a National Semicond) this one is not expensive, but like Jaw says, yeah, is faster to get one from Walmart, I m gonna take a look there, now I have another question, but it s related to the laptop lcd, I m gonna post it in the right forum, Thanks a lot guys, very useful ideas....and don't get mad!! be :wink: :lol: Aldo