Digital temperature sensors

Some ideas for temperature sensors, probably using Dallas/Maxim's 1-wire sensors.

Current sensors

The current sensors and cabling I use were ‘designed’ back in 2002 when I lived in Sydney.

The wiring consists of a twisted pair of wires, taken from a Cat5 cable. The Cat5 cable is pretty cheap, and there's four pairs to every cable, so it's super cheap. Power to the sensors is purely parasitic because of this arrangement, which can be a problem for long cable runs. As pointed out by Brian Lane, Dallas Tech brief 1 recommends connecting a schottky diode across the wires at the end of long cables.

My sensors are simply soldered to the wires of a twisted pair, covered first in Selley's® All Clear (a clear water-proof sealant), and then white shrink-wrap tubing.

My cables are attached using mono 3.5mm ‘phono’ inline plugs and sockets. These seem to have been the cause of some reliability issues.

Better cabling

Better software

Other types of connections

Ways of building 1-wire sensor networks without dedicated cabling.

Internet

Using owserver from the OWFS project, 1-wire networks can be access over any IP network, either local or even global.

Power-line

Wireless

Various options for accessing the 1-wire sensors wirelessly.

Individual sensors

Individual hosts/networks

Small transceivers such as this could be connected to the DS2480B 1-wire host adaptor. This could then drive a whole network of sensors.

Wifi

802.11a/b/g (a.k.a ‘Wifi’) could be used to connect small linux systems into a network, each hosting several networks using DS9490's (USB) or DS9097U's (RS-232). Just a specific type of ‘Internet’ connection which also happens to be wireless.