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Random Source Serge Ground Question
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Random Source Serge Ground Question
harolddonnelly
Hello all,

I'm working on the La Bestia Panel from Random Source and I noticed there are two grounds

+12
GND
GND
-12

I made my connectors using only one of the grounds, as long as I'm consistent in which Pin I connect the Ground, should it work?

For example
+12
NOTHING
GND
-12

Thanks!
SlightlyNasty
The dual grounds are there to decrease the overall resistance of the 0v (GND) return path, to ensure that the 0v reference at the module doesn't move around too much with varying return currents.

It will work with only the one connected, but ideally you'd run two cables - even though they're electrically connected it's all about getting a good cross section of copper going back to the PSU.
harolddonnelly
SlightlyNasty wrote:
The dual grounds are there to decrease the overall resistance of the 0v (GND) return path, to ensure that the 0v reference at the module doesn't move around too much with varying return currents.

It will work with only the one connected, but ideally you'd run two cables - even though they're electrically connected it's all about getting a good cross section of copper going back to the PSU.


Thank you so much for the reply!

If there is too much resistance on the 0V how will that manifest? Through some sort of hum?
SlightlyNasty
It will depend heavily on the circuit - basically it means that any time a part of the circuit draws current, the local 0v will shift according to the amplitude and direction of that current. This will then affect other parts of the circuit as well, many of which often rely on the 0v as a stable DC reference voltage.

A classic example in modular systems is oscillator bleed - when something like the current pulses from an oscillator's sawtooth core resetting show up on the shared 0v line as voltage pulses, that then find their way into the output signal of other modules.

Generally you can filter the +/- power inputs to stop most high-frequency stuff getting into and out of each module, because no well-designed circuit ever trusts the power rail voltage to be stable anyway, but the 0v needs to stay steady regardless of how much current is currently being jammed down it, which means having as low a resistance as possible all the way back to the power supply.
CLee
Any wire in your power distribution has some resistance. It’s easy to think of the wires as perfect conductors, but they’re not. Because current flowing through a resistor causes a voltage drop across it, when current flows in your 0v wires, the point where it connects to the PCB is something more (or less depending on polarity) than zero volts. Like SlightlyNasty says, that can cause signals to bleed around.

Using 2 wires instead of one is an attempt to lower the total resistance of the 0v return to the PSU.
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