Chassis Grounding

[buffo]

Steve, you know better than that. You're invited to SELEM whether or not you ground your kit!

As for grounding the arc lamp - well, that's pretty pointless, don'tcha think? The thing was already dangerous as hell!

Actually, grounding it wouldn't do a whole lot to make it safer. (There wasn't even a metal case to tie the ground to...) Still, it was cool to watch that thing - even if it was a nasty source of UV. Wonder what Steve Roberts has been doing with it? (Vaporizing samples of hair tonic maybe?)

As for the issue of grounding a projector... The safety issues aren't really the primary driver here. Yes, you can safely insulate your projector against any of the 110 getting to the case. I think the real reason people are harping on the grounding issue is that you want that ground to provide a solid signal ground for your lasers (specifically the blanking circuit) as well as for your scanners, and since those devices are all located inside your projector you need the ground there.

Yeah, you could isolate the whole projector and then rely on the signal ground on the ILDA cable to be a good ground. But I'd rather have a big, fat copper wire grounding everything in the box instead of relying on a strand of # 28 wire in the ILDA cable. But hey - that's just me!

If you are worried about ground-loop issues and are thinking of lifting a ground to eliminate the loop, I think it would be preferable to lift the ground on the host PC that is talking to your DAC.

But yeah, this thread did get a little out of control. Some people are pretty passionate about safety I guess. And to be fair, it's a bit more of an issue in Europe with their 220V mains... Still, you *can* run some electronics without grounding the chassis. I just don't think it's a good idea here.

Adam

PS: I didn't notice that your argon was un-grounded at SELEM. That *is* risky... An ion laser is a completely different animal from a VCR or a George Foreman Grill (or a laser projector even). Between the several amps of DC flowing in the head and the multi-kilovolt starting pulse, I know I'd prefer to have the case grounded in case something went wrong.

[steve-o]

Oh, 'Shielding' against noise (electronic) and 'Ground' as in electrical safety - osha, UL , CE etc.. I see... Thanks Adam, I just dont think I'm a safe kinda guy (although I would never put anybody else at risk--If you noticed at SELEM, I guarded my table pretty well..) unless I wasnt there..
and left my lasers running... well....

Just got yout PS-
-edit- I use a spst momentary contact switch and a 'bug zapper' xfmr for the igniter ckt on that argon and the KV is only present while my finger is on the (insulated) switch. It cannot come on accidentally as with auto-start circuitry on normal ar psu's.

(Vaporizing samples of hair tonic maybe?)

Ha-LOL Steve, what are you doing with that thing?Something fun I hope!

[steve-o]

Adam, As far as analog and digital noise issues go, 2 separate grounds are recommended for each , and a single termination point is best for each one.

[JimBo]

I didn't even think about the ground on the ILDA, putting safety to one side, if you had a fault just think of the cost of repairing your DAC and PC.

Jim