PC and Laptop Power Supplies (Very weird project)

[rightmirem]

Hey Folks,

I am a net engineer and an A+ tech, but I am delving into new realms of electronics and could use some advice for a "bet" project I am working on.

Here is the scoop, I am trying to run a regular PC system (albeit limited PC system) from a laptop power supply. I think it can be done, although might require me to build a power board to convert the laptop output into something the PC board can use.

First, any general suggestions regarding this would be bueno. I sure could use any ideas you have (other than "give it up and don't be an idiot.")

Second, a specific question. The laptop power supply (cord with the transformer on it) I am using is for an IBM thinkpad 600X. It's rated output is 16V up to 3.3 Amps. I have stuck my multimeter on the output and it is coming in at slightly above 16V. I am already working on a board to step the voltages down to +3.3, +/-5 and +/-12 volts for the different equipment.

My question is this. Does anyone know to what level the output of a laptop power supply is conditioned. I.E. Does it come out clean enough to dump right to the motherboard (after stepping it down) or do I need to build a transformer and some power protection into the power board?

In a PC power supply, the power from the wall goes through protection circuits, and transformers and all sorts of other rigamoral before being stepped down to avoid fluctuations in the power. I know that the power supply for a laptop goes right into the laptop motherboard, but there are power circuits on the motherboard. Do they just step the voltages down, or do they condition?

Any thoughts on this would be greatly and cheerfully accepted.

Thanks in advance and I look forward to hearing your ideas!

Mike

[Hpro]

My suggestion would be - to chop this again.. like this - so you don't actually need to make a new board but you could use a board of a old PC POWER DUPPLY - if you hook up the +16 volts "converted to Square Wave" just on th input of the SECONDARY Trnasformer stage with a few modifications you would have all the OUPUTS you need as for the rest of the PSU of which you borrow from the the PC would do for you - there are cirquits of easy and cheap choppers - CONVERTORS - but I fear that 3.3Amp output on that PSU of yours isn't quite enough - So what you have to do then is taking the acutal PULSE from the Primary output stage of the LAPTOP PSU and feed it into the Secondary input stage of the PSU of the PC - making a FEEDBACK or a loop back for regualtion of the line and there it would actually be possible to work -

May TOASTER have some better Ideas on this subject but I'm sure it can be done..
Hopt this helps..

[UTR Enterprises]

HPRO,

Thanks a million for taking a look at the post. I greatly appreciate it. To be sure I am understanding you correctly, what I am to do is basically run the final output from the laptop power supply into the secondary transformer of a PC power supply. Once input into the PC power supply circuit, the existing components of the PC power supply (from the point of the insertion on) should allow me both the voltages and the amperes to run the PC board.

One of the stipulations of this experiment is I cannot modify the laptop power supply. I can make any modifications necessary starting from the normal output of the laptop power supply as it comes out of the plug (the plug which usually plugs into the laptop) onward.

Also, do I need to do a conversion between the laptop plug and the secondary transformer to convert the laptop output to "square wave" or is it a square wave as it comes out from the power supply?

Thanks again. I owe you one!
Mike

[Hpro]

Note:
YOu will need a steady 12*1.414= 16.973 Volt to have a STEADY REGULATION on the secondary side of the PSU output..

Yes if you make a invertor - then it has to contain a PWM - Pulse Width Modulater like the chip SG2535 or TL494 can do and those ones are inexpenive and easy to use and to configure - meaning to build the cirquit - I would go for a 486 on that issue as I don't belive that 16 V* 3.3A will be enough power to actually feed a pentium...In Laptops inside Power regualtor the Currents will be increased and voltages will be decreased and for sure that those devices taking less Power than devices on a regular PC>> anyway 16*3.3 =52.8 is a little bit low to get a PC up and running that's why a convertor invertor would be advisable..then there is the question of how much the overhead of the LAPTOP PSU can handle without to get knocked down..with overhead I mean Maximum RATINGS ..it will not be 3.3 but something like 3.3*1.414(Square root) =4.6662AMPS * 16 volts = 74.6592WATT looks quite a lot better..but still if you hook up a Current Booster then it will draw more than you have availbable - but if designed well - it is possible to at least get the PC started --.. just make sure that the monitor is turned on before you start apply power to the unit as a not started up monitor will cause the MOTHERBOARD to ask for more current that it actually would take..to get it running and we need every little bit of the available current..
Hth