Getting the Most out of Back EMF Decoders

Lenz GmbH has always felt that the most important control for DCC is precision motor control of locomotives. Control of the motor's rotational speed (load compensation) means that regardless of the load, the motor's rotational speed is kept nearly constant. During extremely slow movement (For instance through sharp curves and over a series of turnouts), these decoders always provide the motor with enough voltage. This results in very even and smooth performance.

Often people think the purpose of Back EMF is for grade changes. This is only one purpose. Our back EMF irons out all sorts of seen problems and unseen problems making locomotive  movement as smooth as possible. Unseen problems could be gearing snags, track slightly out of gauge, etc.

The biggest seen operating improvement is the smoothness when coupling and uncoupling. Back EMF reacts much faster then a hand on a throttle, it is as if an engineer is sitting in the cab, increasing speed as the load changes.

The Current List of Lenz Back EMF decoders is :  This is our 7th generation of Back EMF development. We believe we lead the way in Back EMF  with our long history of precise motor control.

STANDARD+  1Amp, 3 functions, the flattest decoder available (.12" thick), mounted on a one side flat board
Silver+ Series 1 Amp, 4 functions, the flattest decoder available (.12" thick), mounted on a one side flat board, delivered with several  pin set ups:
Gold+ Series  1 Amp, Our premiere Software equipped decoder


Getting the most out of your Back EMF!

Most independent reviews (see Model Railroader August '97) rate the LE030, LE130, and LE230 version 5.1 as the best slow speed decoders on the market. But sometimes operators are not getting the optimal performance with these decoders. Here are some hints on how to get the most from these decoders and what to suggest to customers.

First we assume the modeler has a version 5.1 NMRA Conforming decoder and that you have programmed it in 28 speed step mode. (the older Version 4.0 LE131 decoders did not have as superior performance.)

It is important that the maximum speed step (register five) is set. The maximum speed should be set to be the maximum speed that the prototype locomotive has. Because these are back emf decoders setting the maximum speed does not reduce the maximum power available. The reason this is important is that typically model locomotives operate too fast in their maximum speed step and by reducing this to a prototype level (normally about 75% of the model capability) you significantly increase the range available for slow speed performance.

If you program a speed table, choose the average operating speed to be at throttle step 16-18. Ideally you want a table that has each speed step to be 1.2 times the previous value, but in practice once you set the low, high and 2/3 point, the rest of the curve is not as important.

Operating a load compensating decoder is different than a normal decoder. With a normal decoder minor adjustments must be made to maintain the speed of your locomotive over turnouts and through minor switching moves. With a back EMF decoder the decoder is maintaining the speed over these minor obstacles and your throttle changes are made to actually control the speed of the locomotive. This provides the illusion of controlling a large locomotive with a lot of power.

While back EMF is ideal for switching operations and slow speed control, many modelers turn off this feature for locomotives that are typically operated at high speeds, because they want to feel the changes necessary to go over grades.

Hope that helps you obtain better performance with your Lenz Back EMF decoders.