[sdiy] From a commercial standpoint -- has Eurorack "won"?

[rsdio at audiobanshee.com]

On May 1, 2016, at 1:13 PM, Vladimir Pantelic <vladoman at gmail.com> wrote:
> On 01.05.2016 21:32, neil harper wrote:
>>> BTW, I liked how the Oberheim SEM used +/-18 V and then regulated it
>>> down individually to +/- 15V. Also like how -15V is mirror-regulated
>>> from +15V, which has its merits.
>> 
>> Can I ask what "mirror-regulated" is and what the merits are?
> 
> as I understand, mirror regulated means that the negative rail is tied to the voltage of the positive one, so if for whatever reason the positive supply goes away, the negative goes to zero too - and vice versa. the benefit would be to never asymmetricaly supply a circuit that needs a symmetric power supply and thus kill less 2164s.

There's one problem here. If the negative supply goes out, what makes the positive supply shut down? I've never seen a mirror supply circuit that actually has protection in both directions. If someone has a link to such a doubly-protected circuit, I'd be very interested to see it.

Some supply chips have a "power good" output and "enable" inputs. I suppose that a mirrored negative supply could feed its "power good" output into the "enable" input of the positive supply, but that seems like it would create a chicken-and-egg problem. Which supply starts up first? If they both shut down when the other one fails, then how does the pair ever get started?

Brian