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SR8249 Locomotive Decoder VS. R8245 Sapphire Decoder


9 posts


I have read a lot of infomation that i dont understand regarding these decoders, i understand what the R8249 Locomotive Decoder does as i have installed them in my locos, but im trying to work out what i get with the R8245 Sapphire Decoder for the higher cost?



8259 posts

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Firstly the Sapphire is a 21 pin (MTC21) decoder as opposed to an 8 Pin (NEM 652) decoder. The Sapphire when brand new comes with a convertor harness to allow the native 21 Pin decoder interface to physically connect to a NEM 652 8 Pin socket as used in many Hornby locos.


Secondly, the Sapphire has much higher output current ratings compared to the cheaper 8 Pin R8249 decoder. The four function outputs are individually 200 mA each (aggregated to total decoder maximum function output of 500 mA) as opposed to 100 mA per R8249 output**, and the Sapphire motor output is 1 Amp continuous (1.5 Amp peak) as opposed to the R8249 0.5 Amp continuous (1 Amp peak) currents.


Note** the four function 100 mA outputs are a shared current resource with the motor current. The total current for the whole decoder i.e all four functions plus motor must not exceed 1 Amp in total (info taken from R8249 datasheet).


Thirdly, the Sapphire has additional CV controlled lighting dimming and special effects features not provided on the basic R8249.


Fourthly, the Sapphire supports 'Railcom' the R8249 doesn't. Railcom in essence, supports two way communication between the decoder and a 'Railcom' compliant controller (usually non Hornby controllers).


Fifthly, the Sapphire supports 'Asymmetric DCC' the R8249 doesn't. The main use of Asymmetric DCC, allows diode circuits built into the track design to bring locos to an automatic stop at set locations (say for example at the end of a Station platform) independently from the DCC controller being used. This can be used to give a small element of layout automation independently from the DCC controller.


Sixthly, the Sapphire supports advanced 'consists control', 'extended addressing' and 'low speed gear for shunting operations'. Not supported in the basic R8249 decoder.


Seventhly, the Sapphire has a 'fuel simulation' capability where fuel consumption is used in a 'virtual reality' scenario. Thus you the operator, has to make 'fuel stops' on the layout to replenish fuel stocks in the loco else it will run out of virtual fuel and come to a standstill. Not supported in the basic R8249 decoder. Note that the 'On/Off' button only provided on the Hornby Elite controller is used specifically to control this Sapphire feature.


Eighthly, you can program a certain amount of automation into the decoder to perform repetitive functions i.e stop, start etc based on timers without user control using the DCC controller. Not supported in the basic R8249 decoder.


There are a number of other minor differences, read the Sapphire manual for details.


PS - Hardly any of these higher function Sapphire features will be available to you, if you are using the current Hornby Select controller or any other controllers that do not have full CV reading / writing support.

Chris........ Making the wood in the trees visible.

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