[sdiy] Eurorack Grounding Question

KA4HJH ka4hjh at gmail.com
Tue Jan 5 22:28:07 CET 2021

> On Jan 5, 2021, at 1:52 PM, ASSI <Stromeko at nexgo.de> wrote:
> Michael E Caloroso:
>> In my experience I cannot trust ribbon cable interconnects for power
>> distribution.  The wire gauge in ribbon cables is not large enough to
>> handle large currents, and the crimp connection at the plug is not a
>> reliable enough connection.  Ribbon cable interconnects are fine for
>> logic signals where their inherent noise margins make them impervious
>> to flaky connections, but not for for critical voltages such as power
>> supply or CVs.
> These are IDC (isolation displacement contact), not crimp connections (in a 
> crimp both the wires and the contact are plastically deformed to yield a gas-
> tight connection).  No, IDC is not meant for large currents; it was designed 
> for telephone systems originally, which means solid wire, not stranded.  But 
> with that limitation in mind it's still a very reliable contact.  Both are 
> much more reliable than other types of connections when properly applied for 
> their intended applications.

Recently, someone in the DAW-Mac group fried the power supply to his 30" Apple Cinema Display. He wondered why there were so many  small pins on the connectors and so many wires in the cable. Think about it: a 30" LCD with cold cathode backlights and a maximum continuous power rating of 150W?

What do you suppose the efficiency of the HV supply was? Rhetorical question.

This why internal SATA power cables have so many "wires". They have to be small, thin and flexible. The individual conductors are tiny and 3.5" drives use a lot of current while spinning up. I just purchased two 8TB drives that are spec'ed 0.7A at 5V and 0.9A at 12V.

Terry Bowman, KA4HJH
"The Mac Doctor"

Q: Should car stereo speakers be pointed to the rear for more thrust or up for more traction?

A. On long trips, the 20- to 30% improvement in gas mileage you might get with speakers pointing to the rear is certainly worthwhile. On the other hand, if you drive on snow or ice, the extra traction of speakers pointing upward gives you added control.

Don Lancaster

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