Re: X10 woes

On Sun, 18 Jun 2006 13:19:42 -0500, "Karl Townsend"
<karltownsend.NOT@xxxxxxxxxxxxx remove .NOT> wrote:

Our sales barn is in front of the house. There is a driveway alarm for the
sales barn to alert a customer driving up. There is also an X10 sending
device and appliance device to also ring a bell in the house.

sending unit http://www.smarthome.com/4060LV.HTML
receiving unit http://www.smarthome.com/2002.HTML

This worked well for many (12?) years. Last spring it quit, so we bought two
new units. It quit again last fall, two more. It quit again last week, two
more. This time the new ones don't work. What gives, they just don't make
stuff like they used too?

Any suggestions? Is there a better pair of devices from another source?
FWIW, the failure has always been the same - the bell turns on when the
contact closes and then won't turn off when the contact opens - appliance
module stuck on.

X-10 is quite prone to "jamming" by noise because it is an OOK
(on-off-keyed) PLC (power line carrier) system. They were marginal
when they were introduced about 1980, and powerlines have gotten
considerably noisier in the ensuing 25 years. It tries to get some
noise immunity by sending bursts during the zero-crossings of the line
voltage. That sorta worked in 1980, but it doesn't anymore because
most electronic gadgets (computers, TV's, etc) now use switching power
supplies that generate high-frequency noise even during the zero
crossings.

We designed and demonstrated some "bulletproof" FSK
(frequency-shift keyed) and PSK (phase-shift keyed) PLC for bulding
controls but I don't have any of the prototypes anymore. Most of
the building control stuff went to Echelon LON-works comms, which is
cheap to make in volume but I don't know of any low-cost consumer
products using it.

You might consider radio. I recently made a 433-MHz radio control
for a guy's camera. Parts cost about 20 bux. It had a range of
about 800 feet outdoors. (He only needed about 100 feet) That'd
be a "shop season" winter project, though. The radios and little
ceramic antennae are available from Digi-Key and Mouser.

Check out
http://www.mouser.com/radiotronix/


.

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