have another quick read:
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html

In this case your will defeating the ground in the laptop power supply which means any engery being shunted to ground in the event of a fault or spike will have no where to go. You will fry the laptop or burn some wire. Worst case things explode under you fingertips.

Anyway, not a good idea. Instead of the removing the ground, just run the laptop off the battery.

RocknRollover,
You are missing the point. If the transformer fuses, then the high voltage half will be connected to the low voltage half. This will put 120v AC on what should be 12V AC. When the regulator fuses from the high voltage you now have 120V AC where you would normally have 12V DC. If you have a ground this high voltage would go out the ground lug on the transformer instead of out you and your lap top. (Path of least resistance)

I hate to pull rank on you but seriously you are spreading some bad information. I have a BS in electrical engineering, and have been working in the field for almost 10 years. Although you don't need anything more that high school physics to figure this one out.

In the blown laptop power supply case V=120, R~500 ohms => A=0.24 Amp P=IE => P=28.8Watts.

In the car battery example:
V=12, R=500 => A = 24mA
P=IE => P=0.288W
The "elements making up Ohm's law" are always in effect.

Hey another ENG, nice to know!

I bet that laptop power supply is just on 'offline' switcher too. Tiny little flyback transformer in there.

GeckoMusic wrote: RocknRollover,
You are missing the point. If the transformer fuses, then the high voltage half will be connected to the low voltage half. This will put 120v AC on what should be 12V AC. When the regulator fuses from the high voltage you now have 120V AC where you would normally have 12V DC. If you have a ground this high voltage would go out the ground lug on the transformer instead of out you and your lap top. (Path of least resistance)

I hate to pull rank on you but seriously you are spreading some bad information. I have a BS in electrical engineering, and have been working in the field for almost 10 years. Although you don't need anything more that high school physics to figure this one out.

In the blown laptop power supply case V=120, R~500 ohms => A=0.24 Amp P=IE => P=28.8Watts.

In the car battery example:
V=12, R=500 => A = 24mA
P=IE => P=0.288W
The "elements making up Ohm's law" are always in effect.

I agree the potential for problems could be there just not likley, but still there non the less so I surrender.
(honest to goodness, I've been doing it for years on a multitude of laptops, that doesn't make it right, just tried)

Anyway, (not to go off topic but to go off topic.... :D ) I'm still in absolute Awe over the fact that it seems a lot of people around here really dig a basic old Shure 57 or 58 over some of the cheaper LDC's.
I hate most of the LDC's I own on my voice and only recently tried (for the heck of it) my 57. My eye's crossed at the fact that it seems to translate my voice better in the mix....at least during a quick test anyway.
Not that I record or mix very well in the first place but still....who'd a thunk it ? I never even heard anyone say that before.

Sorry, back on topic now...

Sorry to crack down so much, but that is not a thing you want people to think is ok.

Yep SM57 is great mic

qwerty,

It's been nearly a month, are you making any progress on this yet?