BLI Light Mikado

[SkipGear]

That is an odd design, but then again, we are talking about BLI, so it is not all that surprising.  I guess it was easier to install the magnet and sensor at the flywheel than on one of the driver axles.  Not sure why they aren't using motor's BEMF for chuff synchronization (like it is successfully done in other sound decoders).

Not really odd at all. BEMF is not effective at very low RPM. The hall effect sensor is more accurate just more parts. It doesn't really matter where you measure the RPM as it is all connected. Even BEMF based systems have to calibrate against the gear ratio and driver size to get accurate matches.

[peteski]

Not really odd at all. BEMF is not effective at very low RPM. The hall effect sensor is more accurate just more parts. It doesn't really matter where you measure the RPM as it is all connected. Even BEMF based systems have to calibrate against the gear ratio and driver size to get accurate matches.

My Walthers 2-8-8-2 with a QSI Revolution decoder has chuffs in perfect sync with the drivers, even at speed step 1. But of course that something that senses the actual revolution of the drive train (either at the driver axle or motor shaft) will be in perfect sync at all times. But still, with the advances in the decoder electronics, that should not be necessary (and it complicates the mechanism and wiring).

And yes, aftermarket decoders do need to be calibrated to the mechanism, but that is a 1 time operation. And if the decoder is factory-installed, then the calibration is done at the factory (like it was done with that 2-8-8-2 loco).

[Maletrain]

My experience with chuff synchronization (limited to a few steam locos by Bachmann) has been that it really is not a "one time process".  The main problem is that it seems hard-to-impossible to get good synchronization at all speeds from creep to too-fast-to-count. 

So, an actual sensor for rpm, which has a fixed ratio of wheel revolutions to sensor signals, seems like the most reliable way to get a one-step calibration at creep speed that will be appropriate for higher speeds.

[Sokramiketes]

That is an odd design, but then again, we are talking about BLI, so it is not all that surprising.  I guess it was easier to install the magnet and sensor at the flywheel than on one of the driver axles.  Not sure why they aren't using motor's BEMF for chuff synchronization (like it is successfully done in other sound decoders).

Also interesting it the depiction of the coupler.  It again shows the coupler head to be the RMR (Vlk) coupler, but the shank is of the McHenry or Accumate type (plastic whisker spring).  I wonder if the actual coupler on the model has the RMR head, or does it look like MTL coupler.

RMR coupler head. 

[peteski]

RMR coupler head.

Thanks Mike!  So someone besides Arnold is  using that "new" coupler.