I hate the AC-to-DC transformers (wall warts) that come with my ethernet hub, USB hub, scanner, printer, speaker etc.

My computer has a 300W PSU, of which I'm only using 115W (my CPU << 1Ghz).

I propose a DC-to-DC convertor that draws power from my computer, that has programmable DC voltage/current.

It can be programmed via InfraRed interface (i.e., PDA), or via computer software.

I know that ATX PSU is supposed to provide a little standby current for Wake-on-LAN/Ring etc., so those can be used to power my ethernet hub.
-- breadlover, Jan 04 2003

Greenplug http://www.greenplug.us/
I think this has been done.. [dannystaple, Dec 13 2008]

i think i barely understand this but the word "conversion" means that something changes into another thing, how can DC convert to DC? its like a red ball converting to a red ball...
-- Pipucho, Jul 01 2005


He means a DC voltage convertor (similar to a transformer, but it works with DC).
-- Basepair, Jul 01 2005


Even so, it's not very clear to me. Do you mean to have a DC power supply in your computer that provides additional DC power feeds to power external devices? If so, then I think it a good idea.
-- bristolz, Jul 01 2005


Most modern electronic devices, even though plugged into the wall (alternating current of various voltages), actually run on direct current of a different voltage. Somewhere, for each device, there is a converter package. First, a transformer that mucks with the AC to change the voltage, then a widget that clips and smooths the AC to DC (diodes, capacitors and resistors, IIRC).

The converter is hidden inside most computers, but it is there. Many other devices leave it outside, at the wall end of the cord: the wall wart.

Breadlover here is trying to say that the converter hidden inside his computer is bigger than it needs to be, and he wants to use the excess to power all his other devices so he can throw away those aggravating wall warts. He points out that the DC that would be coming out of the computer is not the same voltage and current as the DC his different devices need.

The trick is that direct current cannot be 'transformed' from voltage to voltage like alternating current can be. It can be fed through a resistor or something, and variously tweaked, but there will be some wasted power. I think the power losses will be less than the wasted heat of a dozen wall warts, and I think this is a good idea.

The computer will have to have a dozen DC outlets, and as he says, it will have to be programmable for voltage and current for each one, but that can be done.

More likely, someone already has made a DC power station with multiple outlets. [Later: I just Googled, can't find anything very close.]
-- baconbrain, Jul 02 2005


I think I sort of baked this... I just brought out a 5v (and ground) lead from the PC power supply, and use it for a wifi router, the DSL modem, charging my kids DVD player, cell phone charger, and I used a 12 volt tap for the LCD monitor. 5 wall-warts eliminated.
-- n81641, Dec 12 2008


As for calling them wall warts....try plugging it into the bottom outlet.
-- quantum_flux, Dec 13 2008


I have been thinking about building something like this for a while. I know at least one person who uses a PSU in this way for a bunch of 12V DC devices.

Can I suggest an enhancement - instead of programmed via IR - have a plug/socket interface, with extra pins - the extra pins provide some sort of signalling as to what voltage to provide on that socket. Perhaps a resistor or perhaps a digital signal.

Perhaps I can then suggest greenplug - http://www.greenplug.us/
-- dannystaple, Dec 13 2008


PC power supplies are good; we hooked one up to an oscilloscope and found the output to be rock-solid, at 12V, with barely a hint of AC. In contrast, my 12V wall wart puts out a voltage up to 21V or so at zero current, with a few volts of AC. It apparently relies on internal resistance to produce roughly 12V at some nominal current draw. Pathetic.
-- spidermother, Dec 17 2008


All the electronics I have purchased in 2008 had a wall PSU that was actually a nice little switching power supply. I think the transformer-rectifier wall wart may be on it's way out, In my opinion, a nice step in the right direction. Smaller, lighter, and much more efficient. Most of them are narrow, so they only take one spot on a power strip. (Items: router, baby monitor, cell, phone, Lithium battery charger, IP cam.)

Another cool thing about these is that they will run on 100 to 250v AC or DC.
-- n81641, Dec 17 2008



random, halfbakery