Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!motcsd!mcdcup!mcdhup!mcdchg!laidbak!obdient!vpnet!cgordon
From: cgordon@vpnet.chi.il.us (Gordon Hlavenka)
Newsgroups: sci.electronics
Subject: BSR Remotes and Touch Lamps
Message-ID: <26fe300c-435.1sci.electronics-1@vpnet.chi.il.us>
Date: 24 Sep 90 17:55:05 GMT
References: <1486@vitec.UUCP>
Lines: 29


/* Stuff about touch-switches interfering with BSR system */

These systems work by coupling a high-frequency (relative to 60 Hz) signal
onto the power line.  Usually this frequency is in the 100KHz to 150 KHz
range.  This additional frequency is then modulated to carry on/off/address
information.

The easiest solution is to use an isolation transformer on your CTL devices.
The transformer will pass the 60 Hz, but not the control signals.  This
should provide a fix for you.

"Real" isolation transformers can be expensive and hard to find, but you
can fudge one by putting two standard transformers back-to-back.  Get two 24
volt transformers (or whatever).  Connect the low-voltage sides together. 
Plug one high voltage side into the wall, and the other high voltage side
into the lamp.  Watch your power ratings, though!  a 100W lamp draws .83
amps at 120 volts.  This means that your 24 volt transformers will need to
be rated for at least 5 amps.  This may not be any easier to find than an
isolation transformer, depending on the depth of your junk box...

The "clean engineering solution" would be to determine what's "wrong" with
the CTLs and "fix" them.  A compromise would be some kind of parallel trap
to filter high-frequency stuff at the lamp.  The first solution is going to
be a lot of work, and the second would _still_ require isolation, otherwise
it will likely clobber the whole BSR system.

-----------------------------------------------------
Gordon S. Hlavenka            cgordon@vpnet.chi.il.us
Disclaimer:                Yeah, I said it.  So what?