[oclug] tape drive recommendations
bill at strosberg.com
Thu Mar 28 09:49:24 EST 2002
On Wed, 27 Mar 2002, Brad Barnett wrote:
> 7VDC if you take the reading across those two connectors. However Bill,
> I've yet to see a hard drive that doesn't have a diode after the +5 and
> +12 inputs.
> In short, how is the power going to flow? Until you can respond to this
> point, it doesn't make much sense for me to continue to respond to the
> rest. Even if it is well laid out it is, and politely put. ;)
Unless the drive is floating (gravity-free) in the air, it is usually
touching a computer chassis, your hands, a stack of (conductive) papers
etc. All (even partially) conductive surfaces will form a ground
reference point for the DC voltage. Even air can be somewhat conductive,
depending on the relative humidity.
My point was simple - if you are depending on the power connector ground
reference to be the single point of circuit engagement/disengagement, like
home wiring a light switch, you are taking risks with your equipment.
Also, in today's commodity morketplace for low-end hardware, depending on
the production facility and hardware designer to opt-in circuit protection
devices is risky.
bill -at- strosberg -dot- com
bill -dot- strosberg -at- rcpsc -dot- edu
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