[sdiy] Powering a second bit of kit from same PSU (wiring options)

[ChristianH]

I've always been reluctant to to this at all. If you don't know what's
going on in the two units, you never know how a common signal ground
will relate to each unit's power input.
Say for example, both units use a voltage regulator for an artificial
center ground between both power pins, and use that as a signal ground.
If both centers are not at the same voltage, you may have kind of a
short circuit via signal ground.
(Well, I'm assuming a simple 2 pin PSU - if you have a "real" PSU with
+/GND/-, things are looking much more benign.)

Ok, a DI box may be about *NOT* sharing a signal ground, so this may not
apply here anyway.

Since I never have done this, it may very well that I'm just overly
cautious. Or a coward...

But then, I do hate those ladders of wall warts too, occupying oodles of
power strips. I have to admit, it's tempting.

Chris



On Wed, 18 Feb 2015 13:46:14 +0000 random variate
<randomvariate at hotmail.co.uk> wrote:

> Seeking some advice  please - I have a question on how best to modify the secondary side of a psu to drive an additional piece of kit...
> 
> > I have a well over specified PSU that is currently in use powering a Synth Driver DI rack. Lets call it Synth Driver (A)
> 
> Note: I am pretty proficient in project studio maintenance. In this case I had select a suitable PSU and build necessary cable and 5pin plug assembly for the Synth Driver as it did not come with a PSU.
> 
> > I have just acquired another Synth Driver (B) that has the same power supply requirement, and also did not come with a PSU.
> 
> > However, the PSU I already have can provide enough current to drive the second unit.
> 
> Questions please:
> 
> 1. How best could I wire in another cable to power Synth Driver (B) Can I simply solder on a new cable to the same outputs that are powering Synth Driver (A)
> 
> 2. Are there any issues with regards to any sort of power rail crosstalk/feedback between the Synth Driver units that means I should isolate the power wiring between Synth Driver (A) and (B) in some way?
> 
> 3. Any other issues I should consider?
> 
> 4. Should I just buy another PSU and save the bother, as I should not really mess with the PSU if I am asking these sorts of questions?   :)
> 
> Thanks
> 
> Tim