The Flying Scotsman

QUOTE (qweasdzxc @ 18 Feb 2008, 08:18) <{POST_SNAPBACK}>Yer well whats a decoder cos im like 14 and im new 2 it. so um yeah. btw it OO same as HO like will an OO loco run on HO track
A decoder is an electronic controller that can be installed in a loco to run it on Digital Command Control (DCC). There are two commonly used methods for operating electric model railways. Either use a controller to put a variable output 0-12volts DC on the rails, which drives the motor in the loco directly: this is referred to as DC or analogue. Alternatively, there is a Digital Command Control (DCC) system which has power permanently on the rails, and uses commands encoded on the power supply to instruct decoders installed in each loco, what speed and direction the loco is to run. Most locos are still supplied ready to run on DC, so if you want to run a loco on DCC it is necessary to fit a decoder.

OO uses the same track gauge as HO, so anything sold as OO will run on HO track. HO is a true scale/gauge ratio system at 3.5mm/ft or 1:87, and is the dominant scale for model railways globally. But in the UK a hybrid system is used, called OO. This uses a slightly larger scale, 4mm/ft 1:76.2 but sticks with the HO track gauge, which is undersize at 16.5mm: at 4mm/ft it should be nearly 19mm. The reason this came about is due to the very small size, and some awkward design features of UK steam locos, compared to the rest of the world. To enable UK steam models to fit around the commercially available mechanisms of the 1930's, the body size was effectively expanded by the larger scale, to give a little more 'wiggle room' when fitting mechanisms.

QUOTE (34C @ 18 Feb 2008, 09:50) <{POST_SNAPBACK}>A decoder is an electronic controller that can be installed in a loco to run it on Digital Command Control (DCC). There are two commonly used methods for operating electric model railways. Either use a controller to put a variable output 0-12volts DC on the rails, which drives the motor in the loco directly: this is referred to as DC or analogue. Alternatively, there is a Digital Command Control (DCC) system which has power permanently on the rails, and uses commands encoded on the power supply to instruct decoders installed in each loco, what speed and direction the loco is to run. Most locos are still supplied ready to run on DC, so if you want to run a loco on DCC it is necessary to fit a decoder.

OO uses the same track gauge as HO, so anything sold as OO will run on HO track. HO is a true scale/gauge ratio system at 3.5mm/ft or 1:87, and is the dominant scale for model railways globally. But in the UK a hybrid system is used, called OO. This uses a slightly larger scale, 4mm/ft 1:76.2 but sticks with the HO track gauge, which is undersize at 16.5mm: at 4mm/ft it should be nearly 19mm. The reason this came about is due to the very small size, and some awkward design features of UK steam locos, compared to the rest of the world. To enable UK steam models to fit around the commercially available mechanisms of the 1930's, the body size was effectively expanded by the larger scale, to give a little more 'wiggle room' when fitting mechanisms.
Thanks that was a very clear answer.