4.7k Ohm between +3.3v (pin1) and signal (pin7 = gpio4) close to the RPI
each one wire sensor gets V3.3, Ground, Signal
If the distance is not too long you can run them in parallel = all wires stop at the RPI (star)
signal wire:
RPI == V+, Ground Signal==> sens1
RPi == V+, Ground Signal==> sens2
RPI == V+, Ground Signal==> sens3
If long (> 5 m) better to do (serial)
RPI == V+, Ground Signal==> sens1 == V+, Ground Signal==> sens2 == V+, Ground Signal==> sens3 == V+, Ground Signal==> ....
And if very long you can add a 1uF capacitor at the last sensor between +3.3v and Ground
+ connector to put on the pins of the RPi (pins 1,7,9)
eg "2.54mm Breakaway PCB Board Female Header Connector" you need a 5 pin wide (pins 1..9 left side)
so in summary
n times 18B20 sensors ~ $1 in qualities of 10
1 time 4.7KOhm
1 time 2.54 mm female connector 5 pins
x feet/ meters of cable eg "Copper Wire 24 Ga" or thinner ... any isolated wires will do
And when I am done, I dunk the sensors into "liquid tape" to isolate everything .. takes 2 hours to dry
You can get everything at amazon or on ebay.
Total cost ~ $15 for 10 sensors with cables, connector, etc (+ liquid tape ..)
Karl
see
http://forums.indigodomo.com/viewtopic.php?f=187&t=15563 for schematics etc