Sunday, October 12, 2014

ESU - Decoders - Throttle Response


While at the Liverpool exhibition, I was talking to Ian Phemister about an ESU ROD sound file that he had purchased. While I have not heard the ROD sound file, Ian explained that you could 'drive' the locos sound using throttle speed step inputs.

While most ESU users are aware, when you drive the loco, you set a speed setting and the locomotive sets off. In most cases when the locomotive is accelerated quickly, depending on how the sound file is set up, the locomotive will usually start to chuff louder, simulating a hard working engine. Once the difference in requested speed and actual locomotive speed closes, the locomotive automatically transitions into a quieter chuff sound. When I say 'in most cases' I mean that not all ESU sound projects are the same in how they behave. There are many steam projects available on their website and many have slightly different drive architecture.

A few blog posts back I came up with a method to push the drive sounds into the acceleration sound (hard working chuff) area using a function button. This does work well and allows the locomotive to move at a constant speed working hard (does not automatically revert to quite chuff sounds). While this option is good, some people do not have spare function buttons available to use as a drive sound modifier.

While I have not heard Ian's ROD file, I decided to have a play around with my C38 sound file. I have modified the drive sound transition settings to allow the locomotive to remain playing the acceleration sound files, even when the speed requested equals actual locomotive speed. The acceleration threshold has also been lowered to make it more responsive into the acceleration area. This could probably be relaxed just a little so the locomotive can be more easily crept up to speed quietly, perhaps in the case of a light engine movement or a descending start. More refining required.

Once the locomotive has reached the user's desired speed they can leave it there and let the loco work hard or they can pull the throttle back one speed step and relax the chuff sound into a quieter beat. Once quietly chuffing along, if wanted the throttle can be moved back one more speed step and the locomotive will coast along with no chuff sound, simulating a shut off regulator setting.

While this method works well, one negative is that you need to reduce the speed of the locomotive one speed step to affect the sound change. While it is not to big a change in speed you can still detect the slowing chuff rate.

Moving ahead with this, I would like to have this option selectable. With the press of a button you could select between the two drive modes. I know this would also use a function button but this could be moved to a less used number.

I have made a short video of the C38 running. Would like some feedback on this, especially from those that have used the ROD file.



Sunday, October 5, 2014

Points Please


Just a quick update, well actually more of an advice seeking post. Point building has been going slow, mainly because I have been trying a few different methods and ideas while trying to come up with a standard building process. The time has been spent mainly on the switch rails, both on hinging them and also coupling them together by stretcher bars (I think that's what they are called?). The method used for stretcher bars is probably nothing new however I like the idea of easily removable switch rails for future repairs. I didn't want the switch rails soldered to stretcher bars or connected in too a complicated fashion. The switch rail hinges are stainless Proto87 store items and work very well. The switch rail can simply be pulled out of the hinge.

The method of stretcher bar fitment involves drilling two holes in each switch rail web and pinning to pieces of PCB strip with phosphor bronze wire. My intention is to camouflage the PCB strips and add decretive prototypical stretcher bars made out of styrene and brass. I made a small jig out of brass to aid in drilling the holes in the PCB strip. This keeps the switch rails at the exact distance part. At this point I may have to use a slightly thinner bronze wire as I feel they are a little bulky.

If anybody can see huge errors in this design please let me know. Ballasting may be an issue as well as not being able to disguise them well enough. I have been thinking about thinning down the PCB strips in width around the centre. They do move very nicely and the switch rails close up nicely onto the stock rails.

You may also be able to see that I have added a few stock rail support chairs. These are of the Stephen Johnson Models variety and have been chopped up so as to fit the sleeper plate etches. Not sure if they look that great at this point. Perhaps after a good clean up and paint they may look better.

Yesterday I enjoyed the Liverpool exhibition. It is always good to catch up with everyone and also meet new people. I was in the bad books when I got home as I bought another PSM 38 class without prior finance minister approval. The wedding is still on, so I can safely say I got away with that one! Still looking for that all green non-streamliner though ha.

Well that's about it for now,