Hi, yeah...i'm sure this question is super-ignorant, ultra-beginner level, and i'm showing my drastically limited understanding of electrical devices...but here goes
Why does my power supply module (which is the uZeuz power unit of the Tiptop Happy Ending 19" rack kit, but I presume this applies to many such units) have one supply for ribbon cable that is +12v and another for -minus 12v
I'm powering my modules off the + 12v, but can someone explain what the minus - 12 v is all about, and what that would be used for?
In electrical circuits you always have a +Plus and a -Minus, think of it as turning on a light swtch to join the two and you get light.
Connecting your power cables the correct way around is important.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.
Eventually i messaged Tiptop's tech support asking about what modules should be attached to the positive bus, what should be attached to the negative.
They just said that it doesn't matter, because all of the busses supply all of the types of current.
I've certainly had no blow outs or functionality issues with any module. I did dutifully connect the one module i have that says it wants neg to the neg bus. Why not? But then again, why? since all busses carry all polarity combinations?
As a person who likes to imagine i'm vaguely logically minded (albeit , i admit, with limited knowledge), this does leave me wondering why the different busses are defined as positive and negative polarity? Whatever the answer is to that (if there is one), it certainly isn't to do with the polarity of then current that the busses deliver, since all the busses deliver currents of all polarity.
Guess I may never know.
And it apparently makes no practical difference
The bus current is polorised +/-
Pretty sure their modules will be made to correct their own polarity whichever way you plug them in.
Not all manufacturers do that.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.
This is a dead thread but because the question was never properly answered:
Each power bus/ribbon cable on the uZeus (or any Eurorack power supply) contains wires carrying all of 0V, 5V, 12V, and -12V. This is what TipTop meant when you asked which bus to use: Either one, because both buses contain all of these voltages. There isn't a "positive" and "negative" bus in that way. Sometimes people may refer to any one of the voltage supplies within the ribbon cable as a bus, which is reasonable if you're drawing up a schematic for a single module, but less so if you're connecting multiple modules in a case. Personally, I'd use "Power Bus" to refer to the entire ribbon cable's worth of power supplies.
It is important to always connect your modules to the ribbon cable correctly: There should be some indication which side of the module's power connector lines up with the red wire on the ribbon cable (which indicates the -12V side of the ribbon). If not, call the manufacturer and chastise them for not making that clear.
A common use case for the -12V supply is amplifiers: if you want to amplify a signal that goes below 0V, it's helpful to have a negative-voltage power supply to make that happen. This could mean VCA modules, or just op-amp components (which appear in almost any analog circuitry).
