On 18/05/2011 06:32, IVP wrote:
>> I'm probably missing something here, but how were you thinking the
>> SMPS would solve this?
> Aw, dirty pool, making me think on an empty stomach ;-))

I do apologise  - on the other hand I've just this minute finished a=20
very tasty special chow mein + fried rice.. :-)

> And now that I do, it probably doesn't solve anything wrt to a mains
> fault. I suggested it as Michael mentioned the possibility of a 48V
> shock. Making a controlled 48V within the mic with an SMPS from
> LV was just a thought. It is just as possible to have a fault on a LV
> supply. But, specifically, if the current-limiting of a 48V supply was
> somehow bypassed, it would be more likely to shock than unlimited
> 5V
>

Ah, I see - I thought that might have been what you were thinking of=20
after more consideration, which makes sense as <12V is very unlikely to=20
cause problems compared to 48V (unless you apply directly across the heart)
You can get also get condenser mics which work okay on these low=20
voltages if you didn't want to roll your own.

> For any situation to become hazardous it would take more than one
> factor. eg if the chassis became live there and was no good ground,
> RCD and/or fuse, the mic was not insulated, in the left hand etc

Yes, unfortunately Murphy often conspires to find just the right=20
circumstances for these things to occur.
I know from experience that it happens more than it should do,=20
especially in the case of the music industry where you have a lot of=20
(often badly maintained) old equipment still being used. There are so=20
many links in the chain with something like a live/studio setup, it only=20
takes one or two to be flaky and you have problems.

> To be absolutely safe every potential (no pun intended) failure point
> should be addressed

Yep - I think if it was me standing in 3 feet of water I would probably=20
opt for something that ran on a couple of AAs :-)



--=20
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