"The only 'stupid' question is the question not asked"... With that said, I'm curious. When turning the throttle knobs on the DT402 a soft "chirping" sound is emitted. Ofttimes the "chirp" is accompanied by a step up/down in the speed displayed -- two "chirps" display one step up/down in scale speed. Is there a connection between the "chirp" and scale speed? Or, just coincidence? Thanks, for your patience.
The DT4xx throttles don't actually display speed, it's more or less the percentage (0-99) of speed steps. Not adding more digits to the display to show 128 speed steps was a design compromise that had to be made.
As for the chirp, that's a setting that can be changed. See your DT402 manual.
The design choice was to make the display consistant regardless of the number of speed steps being used. 14, 28, or 128, the display always goes from 0-99% instead of 0-14, 0-28, or 0-128. Digitrax early on made 128 steps their default, many others are only 28.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy,
whats your view of 128 vs 28?
Joe
128 all the way, much finer speed control, more akin to a DC power pack. It also makes jackrabbit starts almost impossible (depending on the ballastic tracking setting).
It was an argument early in the DCC discussions, before the standard was ratified. The people on the Lenz side were all "14 steps is more than US prototype diesels even have" (not totally true, Baldwins had continuously variable air throttles, no notches at all, and others had 22). Plus it ignores the fact the physics doesn't scale. 8 notches is fine for a real loco with thousands of tons of train behind it. And steam locos have a heck of a lot more than 8 detents on the throttle quadrant. The US groups led by AJ from Digitrax and to some extent Jim Scorse from NCE are the ones that pushed for the extension the the original Lenz protocol to allow 28 and then later 128 speed steps.
There are enough differences between both prototype and model railroading in Europe that make the designs of DCC systems much different. Euro locos, if they even have numbers, are much more than 4 digit numbers, os the pictorial depiction of a loco for selection is much better for them. Very rarely did a US railroad use more than 4 digit numbers on locos, and it many cases it's only 2 or 3 digits, making a "key in the cab number" selection IMO much easier to use than going through a bunch of pictures of similar locos (case in point, I have 8 RS-3's and that roster is only going to grow). There seems to be more of an emphasis on automated operation, hence the rwquirement that the loco covers a set distance in a very consistent manner. BEMF to this level to US modelers is like cruise control, where the loco spped never varies up hill and down, with 5 cars or 50. At the Philly NMRA show I remember one vendor showing off their BEMF by having a G guage circule of track mounted on a piece of plywood that could be tilted from flat to 45 degrees. When tilted at 45 degrees, the loco they had running around never slowed on the uphill side nor sped up on the downhill side. A fine example of an excellent motor control design, but not something I'm particularly interested in. I like BEMF because it helps make ultra slow speed starts work, but I don;t want BEMF so strong that I never have to touch the throttle even on the steepest grades, that's not realistic operation. The newest sound decoders use this to adjust the prime mover sounds based on load, which works very well.