[sci.electronics] random brightness blinking Xmas lights on your tree

rfc@briar.philips.com (Robert Casey;6282;3.57;$0201) (11/04/89)

random bright xmas lights  

Here's a simple circuit to create a nice effect with those small xmas
light strings on the tree.  Get an even number of light strings, some
with blinkers.  Getting pairs of sets would be good, but not critical.
Get a pair of 120V outlet sockets, and wire them in series.  Plug in
half of the strings into one of the sockets, and the other half into
the other socket.  Connect the series wired outlets to the powerline.
Any one string of lights will have about 60V across it.  When some of
the blinkers start working, some of the lights will vary in brightness,
some brighter, some dimmer, and of course some go out!  The
time-brightness pattern will be random.  Of course, the lights will
always be dimmer than when you plug them in directly to 120V, but
they're still plenty bright enough.  And they will last much longer.
It works best with 8 or so strings.  You may want to swap around
strings to fine tune average brightness levels.

   +-string--+  +--string-+
   I-string--I  I--string-I
   I-string--I  I--string-I
   I-string--I  I--string-I
   I-string--I  I--string-I
   I         I  I         I
   I socket  I__I socket  I
   I  ____________________I
   I  I
   120V


ckt detail    _________________
   __        /                 \
--I  \------+  socket socket   /
--I__/----------I I----I I----+
120V plug

73 de WA2ISE
(you got lots of time to do this! :-)