Re: X-10 RF home automation being overwhelmed by M2 OFF, C2 OFF and Gxx DIM signals

[bud-- <remove.budnews@xxxxxxx>]

On 8/29/2011 8:48 PM, The Daring Dufas wrote:
> On 8/29/2011 3:01 PM, Robert Green wrote:
>> "The Daring Dufas"<the-daring-dufas@xxxxxxxxxx> wrote in message
>> news:j3gi0g$89e$1@xxxxxxxxxxxxxxxx
>>
>> <stuff snipped>
>>
>>>
>>> Back in the late 1980's I was working and living in the country of
>>> Californiastan when the community I was in at the time started having
>>> problems with their electric garage doors opening and closing as if
>>> possessed by some evil door opener. It turned out that the US Navy
>>> was testing the big search radars on some ships in the bay. Those big
>>> powerful radars were producing an RF harmonic signal that was just right
>>> to screw with the RF remote controls for a lot of openers. :-)
>>
>> Yes, I was aware of them. Lutron's Radio RA system had to add a second RF
>> channel in NYC because of interference from a source that wasn't going
>> away.
>> Read: government.
>>
>> We just had a round of that a few years ago near DC at Andrews AFB and
>> others in Denver had the same problem. I know that two military research
>> labs nearby (I live between the two on almost a perfect straight line are
>> tasked with IED jammer development so I wouldn't be surprised if the
>> signal
>> correlated with elevated threat levels. The DC area is as the Pentagon
>> says
>> "target rich environment."
>>
>> But in reality I think Dave is probably onto the real source: The local
>> power company has just instituted a program where they hook a
>> receiver/relay
>> between your AC and the powerline. In brownouts, they can shut your AC
>> off
>> remotely. I was going to apply for it because we don't use our CAC
>> anymore
>> and have switched to window ACs, but that seemed to be cheating so I
>> decided
>> not to.
>>
>> The "blips" started appearing a month or two ago, when summer began. They
>> are not there today, with the temps in the cool, dry 70's (the benefit
>> of a
>> hurricane - wonderful, cool, clean air for a day or afterwards). Now I
>> have
>> to download some temperature data and try to correlate that with the
>> times
>> the bogies appear in my Homevision log file (records all externally
>> generated commands to log file). The days of endless bogies generate huge
>> log files, 100 to 1000 times the normal size.
>>
>> --
>> Bobby G.
>>
>
> I'm an old broadcast engineer/two way radio tech and I had to track down
> RF interference all the time. My friend who worked for the local
> power company as an electrical engineer in charge of their
> communications told me that back in the 1970's they were tracking down
> a lot of RF interference caused by doorbell transformers. I have an
> idea that today's proliferation of "Wall Warts" could be responsible
> for a lot of RF and power line borne interference. It's something to
> consider.
>

Doorbell transformers sound really bizarre as a source of RF. Somebody
at a.h.r tracked down a source that says it is from contacts that
disconnect the transformer when the current is too high for a class 2
(limited energy) transformer. (Or something like that.) Contacts would
repeatedly open (with arcing) and close.

My guess is that class 2 AC-out wall warts are "impedance protected",
which most doorbell transformers probably are now. At too high a current
the voltage just droops.

My guess is that DC wall warts are the same, or the DC side has a
current limit circuit. Are they switch-mode these days? Wouldn't think
switch-mode would be worse than other switch-mode power supplies found
all over the place.