What Does This Mean? Regards Decoder Amp Ratings

[KisNap]

Hi Everyone,

     What does the phrase below mean?  I saw it when looking for a decoder for a locomotive.  Is .8 Amps the max draw for the decoder?  It sounds high considering it's N scale and doesn't have sound.  Thanks.

MRC AD330 N Scale DCC Decoder 0.80 Amp

 

[da1]

0.8A is the maximum current that can be delivered to the locomotive's motor.

To find the maximum current your loco will draw apply full DC (usually 12Vdc) and hold the wheels so the motor is stalled.  (Needless to say this isn't good for the motor so be fast!)  The current measured here is the loco's 'stall current' and must be less than the maximum current rating of the intended decoder.

 

[richg1998]

There are other brands of sound and non sound decoders that are 1 amp limit and are N scale decoders but useable for HO. 

Sound has nothing to do with current rating. Current rating is only for the loco motor and lights. With some HO locos, real light bulbs, not LED's are used and draw more current than LED's.

Rich

[rrinker]

 The amp rating of something that supplies power - DCC booster, power supply, decoder - is how much power it CAN supply. A 5 amp booster does not 'push' 5 amps on the track, it supplies whatever power the load is drawing, up to 5 amps.

On a consuming device, like a motor or light bulb, it is how much current is needed to run that device. In the case of a motor, it's at maximum load on the motor. So if the motor says it draws .5 amps peak, it will draw between 0 and .5 amps when running. It a light bulb is rated for 30ma, ir draws 30ma (.030 amps) when on.

LEDs are an exception. They are driven by current not voltage, so the current rating for an LED is the maximum you can allow it to consume. This is what the resistor in an LED circuit does, limits the total current flow to the LED.

                         --Randy