Custom NXT^® cables

Once you master NXT plug synthesis, it's easy to create cables with custom length, as exemplified in the short cable above. You can also choose more flexible cables, round instead of flat cables...

Only one thing is really important: NXT cables are "straight" cables. That means that the same wire must be connected to matching contacts at both ends of the cable. With a flat cable, the connectors latches are thus placed on the same side, and on opposite face:

December 2006 update: several cables kits are available:

• LEGO 8529 kit contains 7 cables, identical to those in 8527 NXT kit: one 20cm (8.5”) cable, four 35cm (14.5”) cables and two 50cm (18.5”) cables.
• HiTechnic NWS1000 kit contains 4 cables with different lengths:12cm (4.75"),16 cm (6.3"), 70cm (27.6") and 90cm (35.4"). These long cables can be handy!
• Mindsensors Flexi-Cables kit contains 4 cables with the same length as the LEGO ones: one 20cm (8.5”) cable, two 35cm (14.5”) cables and one 50cm (18.5”) cables. Especially noteworthy - and useful! - is their flexibility, much greater that regular NXT cables.

Compatibility cables

A more interesting application of synthesized plugs is to build "compatibility cables" that allows you to use your old RCX sensors and motors with the NXT. LEGO sells these cables through its education channel (see here), but they are not yet available as of this writing.

Warning: as of this writing, programming software of the retail version of NXT kit (8527) doesn't support the use of some RCX sensors such as rotation sensor, light sensor or temperature sensor. The old touch sensor will work fine when used with NXT touch sensor block. RCX motors will work too with NXT motor block but of course all advance features that depends of the built-in rotation encoder can't be used.
 

	We need one piece of NXT cable, obtained as explained here, and one half 9V cable.
	Only wires 1 and 2 of NXT cable are used for RCX stuff conversion. These wires are the ones on the NXT connector latch side. The other 4 wires are not used and are cut flush to the cable (warning: take care to make a clean cut to avoid short circuits between these unused wires). All ends of wires are stripped and pieces of insulating heat-shrink tubing are prepared. The order of wires is not very important since the 2x2 9V connector allows changing the orientation.
	Wires are soldered together. Heat-shrink tubing is ...heat shrunk.
	Heat-shrink tubing helps isolating wires and provides some strain relief.

December 2006 update:

As of this writing, programming software of the retail version of NXT kit (8527) doesn't directly support the use of some RCX sensors such as rotation sensor, light sensor or temperature sensor. You will have to download and install the Dynamic Block Update and the Legacy Block Library. The conversion cable (8528) is available from LEGO.