Wanna power this laptop since I fried my system today.
The laptop requires 15v, and I've got a car PSU that gives out 20v and another car PSU that gives out 5v. I got thinking, the potential difference between the two PSU's positive wires is 15v. Would this be ok to power the laptop?
I`m thinking of trying it tomorrow, but somehow I get the feeling it's gonna cause ground loops and all sorts of havoc, so it might not be worth bothering.
I'm gonna get a proper 15v PSU eventually, it's just that the E-bay auction doesn`t end for a couple of days, and I`m stuck with silence in my car since I fried my computer this morning.
Here's how it happended:
I powered up my computer today, except it didn`t fully power up. The power LED came on, thats about it. So I tried it in the house, and measured the voltage coming outta my sproggy.... All was good until I found the 5v rail was actually giving out 8v! So, I unhooked the sproggy, and tried a mains PSU on the computer and it did the same thing.... sat there with just the stupid *** power LED on, and nothing else. I reackon the sproggy fried the motherboard.
I tried powering up the sproggy with nothing attached, and it gave out 12v on the 5v rail. So, just for the sake of curiousity, I tried wiring it up to a crappy old quad speed CDROM drive. It appeared to work. Even tho the 5v rail was now giving out 10v. I pressed eject, and the tray shot out faster than i've ever seen in my life. It almost took my hand off.
I gave up after this, thought "sod it", and got straight to work on the laptop. Btw, If anyone has had a similar thing happen to thier sproggy? I'wanna try and fix it for mark 4 (see sig).
Wow..thats a crazy idea. LOL dont bother im sure you can live without music for another 2 days or so.
So you want to connect the 0V of the laptop to the +5V supply and then connect the +15V of the laptop to the +20V of the other supply to give you 15V in total. It can work it just that your laptop 0V is +5V above the cars ground.
Its easy to forget this and connect another circuit that can short your +5V supply.
And how about the current rating of the regulators?
Naah leave it...sound too messy.
Yeah that should work...I guess your laptop battery will never get charged properly but im sure you dont mind that...you got plenty in your car + the alternator =)
I found a circuit that could've saved a lot of trouble. It's the classic crowbar. It's only purpose is to blow the fuse in case of an overvoltage. I have never tried it myself but some say it works.
Thanx, I think I`ll add it to my sproggy when I get it fixed.
Still got lots of other stuff to do before MK4 is ready tho...