Never buy a DS18B20 from eBay! Its a premium priced sensor and the scammers are all over it now. Scammers quote lower prices than the legitimate sellers and make it unlikely you'll find a legitimate seller for such devices.
Buy a genuine 3-lead TO92 Maxim (Dallas Semiconductor) DS18B20 from a reputable supplier.
Read the datasheet and make sure you read the bit about pull-up resistors (the device works by pulling down lines).
Get that working - they do work very well - then experiment with two wire set-ups.
If you don't need the small cable cost savings by using two wires instead of three, always go for the two wire set-up.
You can get cheap multicore cable by buying say, 100-metres of Cat5e which will keep you in 1-Wire cable for years.
This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.