* Posts by dwarmstr

3 posts • joined 28 Jun 2010

HP ProLiant power supplies 'may die when dormant'

dwarmstr

Electrolytics need voltage

The electrolytic capacitors need a voltage to maintain the Al2O3 layer that acts as the dielectric between the aluminum and the conducting paste that are the two plates. You can reform the layer by gradually increasing the DC voltage applied on startup. This is a standard technique when examining old antiques.

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Silicon to stop next-gen powerline standards war

dwarmstr

Regarding the radiating interference

X10 runs at 120kHz, low enough not to radiated well and in a band that is not widely used. The other uses are fairly intermittent use and aren't in 2-30MHz. Power-line networking, since it's using 2-30MHz, is using the shortwave band used by 1. amateur radio users 2. international broadcasters 3. ocean-crossing airplanes 4. ocean vessels and 5. a myriad of other users. 2-30MHz is radiated very effectively from house-sized wiring as it matches roughly the right antenna length. All the other users of this band have the allocation and authority to use it free of interference, and here's where PLC causes problems--it breaks this authority and allocation.

Hmm.. I was going to point out the PLC could have spent the time to get an allocation somewhere and then no one would complain about interference, but now I wonder if you could utilize the ISM bands for the PLC frequencies. No one would have an issue with that, except the cable loss would be rather high and I wonder if it would "interefere" (you technically can't interfere in an unallocated band) with wifi.

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Power line tech could crash aircraft and shut down the Archers

dwarmstr

much more than amateurs "down there"

"Existing PLN equipment operates between 2MHz and 30MHz - right at the bottom of the dial. The only things down there are the amateurs, who've been complaining for a while now, and a few vertical users who don't operate near the homes where PNL is being deployed"

And long-distance over-ocean aircraft, international broadcasters, many federal agencies, the military, shore-to-ship comms, etc.-- PLN affects it all. Having much higher frequencies involved is a mixed bag; using them and dropping the under 30MHz spectrum would keep intact the world-wide nature of the shortwave; but higher frequencies would radiate better out of the power line wires. A better approach is to drop the whole thing and stick to technologies that don't radiate outside of prescribed frequencies.

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