Hi, for a new hardware mod I would need 3,3V 1.5A from extern connectors on a laptop.
USB offers just 500mA per plug, anyone got hints how to e.g. connect three of them to get 1,5A?
Or should I use Firewire? this one got 1,5 Amps but no 3,3V line ...

Anyone got a cheap quick'n dirty wiring? All ideas welcome.

thanks!

ahu

ahu you may use for ex: 3 diodes 1n4007, 1 electrolytic capacitor and LM1086-3.3 regulator for usb port.

Ex diagram:

                                                                                                 ________
usb ports 1 ---------|1n 4007|/|-----|                                         |              |
usb ports 2 ---------|1n 4007|/|-----|------------ (+5v 1.5A)---     |              | ( LM1086-3.3) (3.3V VERSION)
usb ports 3 ---------|1n 4007|/|-----|                                    |    -------------
                                                    ---- (+)    16v/100uf         |    |      |       |
                                                 --------- (-)                           -----      --------------- out +3.3v 1.5A
                                                      |                                      (in)   (adj)  (out)
                                                      |
usb ports (1~3)------------------------------------------------------------------------------ out -3.3 v 1.5A

For firewire you may use only  a regulator lm317 (this regulator have output of 1.5A) and only one port.

Warning this may be damage you laptop if you use it from battery.
For this you should use a transformer connected to AC 220v.

if you tel me what device you try connect to your laptop, i will help-me more.

opensys, thank you very much for your diagram. Your warning insecures me a bit - what is the worst case that could happen? Would it blow up the whole laptop (say e.g. usb chipset) or just the battery? If it would just drain the battery, that would be ok for me.

The device is a w-linx router, stated 3,3V 1,5Amps.
http://www.w-linx.de/products/en/W-Linx … White.html

I have already used some of their usb powered switches (below 500mAmps though) in a switch and a laptop - now I want to replace my mini-pci wifi-card in my laptop with the w-linx router pcb (winnig a hardware build in router and if needed, an repeater). I could attach a pointing antenna to it, raising the range. The ac/dc adaptor says 3,3V - 1,5Amps, maybe 1,0 Amps would do it too. I haven't tested it yet.

ahu,
the worst that can happen is blow the internal usb laptop fuses, damage the laptop power supply circuit and the more probably one is damage the laptop battery.
I not advice you to use the w-linx  router on your laptop seams that the router takes very power 1.5A is too much and the laptop battery will be decrease very quickly.
My experience is with one router connected the laptop by usb, the fonera 2200 works fine, and the transformer is 1A but seams that works fine with one usb port 500ma, i check also with a multimeter, and takes 400, 450 ma with wireless on.
In your case if the problem is substitute the mini-pci wifi-card, buy a new one thats give you what you want , not substitute it with a router.
Other way is get power from a sunny with electric foto cells.

Thank you for your suggestions opensys, I'll try it with some battery packs from my rc cars, did not even thought about that. 3,6V packs in parallel should do the trick. Just have to check how long they will last for mobile issues.