Introduced 1987-89, these models, which were manufactured by Kato and sold by Atlas, have excellent mechanisms and are great candidates for S-CAB battery power and radio control. The cast metal frame is heavy enough for traction, but leaves space above the motor for electronics and battery. With some careful trimming of the body shell, this space can be extended the full length of the loco. The completed installation (photo left) shows no evidence of any modification to the loco.
This description illustrates use of a circuit board (sometimes called a "motherboard") to simplify installation and complete as much work and testing as possible on the workbench. Wiring within the loco is minimized by mounting front and rear lights on the components circuit board. As a result, there are no wires connected to the body shell, which can be removed and replaced without restriction. The project involves modification of the loco body and frame, assembly and test of two subsystems and finally, installation.
Traces on the loco interface circuit board are used for rail pickup connections to front and rear trucks. If convenient, motor connections can also be to this board, which makes a total of 6 wires (2 to each truck and 2 to the motor) to be disconnected should it ever be necessary to remove motor or trucks.
The component board sits on top of the interface board and is held in place by electrical tape.
Since LED lights are mounted on the components board, there are no connections to the loco body, which simply slips into place to complete the installation.
I occasionally hear from an S-CAB user (Michael) who models On3. Since he's an innovative guy, as well as a skilled modeler, his feedback is always interesting. His latest effort is an S-CAB radio and BPS battery power supply installation for a Climax loco.
Here are Michael's comments:
Thought you would like to see my latest car (trailing) for the battery and BPS electronics board. The decoder/wireless/speaker are in the Climax but I need a car for the battery etc.
You will note the two pipes (lower left with the chain over the pipes) – these are for power to the loco – there are two small plugs on the loco on the same side, so thin wires will do the connection.
Also, on the top rear of the tank are two small pipes – one higher than the other – these are the recharge points. Just plug in the power supply and the recharge will start. The tank is not firmly secured on the flat car just sort of held in position with the chains. The barrels etc are glued down. The chain (not glued) at the back is part of the chain keeping the tank in position.
I have two magnetic reed switches (the ones you supplied) glued up at the top inside both ends of the tank. So I just wipe with the magnetic wand for start and stop.
In the background is another battery car – the tank.
This is a complete battery power, radio control, sound installation in a Bachmann On30 Forney. The entire system fits under the coal load with the battery barely visible where it protrudes on the floor of the driver's cab.
Since this model already has a factory-installed non-sound decoder, the hope is that installation can be simplified by use of existing wiring to motor, headlight and driver wheel rail pick-ups. It's also convenient that the fuel bunker is a separate molding attached to the frame by 4 screws.
Begin by clearing the clutter and planning efficient use of available space. Laying the battery flat on the loco frame and using space in the cab accommodates a 500 mAh battery. Obviously, the speaker must be mounted elsewhere. Internal space within the fuel bunker is 40 mm long, 40 mm wide and 22 mm high. Since the battery is approx. 6 mm thick, the challenge is to fit a sound decoder, S-CAB radio receiver, BPS battery power supply and speaker in the remaining 16 mm above the battery. Several arrangements are possible, but I eventually decided on a major rework of the BPS circuit board to make it a "middle layer", with radio receiver and speaker mounted at the top of the assembly. This gives good speaker acoustics and keeps the radio antenna clear of metal surfaces and wire tangles.
Modified BPS board
BPS has 2 standard arrangements. The long configuration can be cut in half and the 2 halves mounted back to back to form a short configuration.
This is the standard, one-sided BPS circuit board
At this point we have an installation plan and a modified BPS circuit board. Let's determine if everything fits.
What to do with a tangle of wires is often considered too late in an installation. For this model, the entire installation must fit a space measuring 1.575" square (40 mm) and 0.79" high (20 mm). The planning process included component placement as well as arranging wires to minimize both quantity and length while still being able to make the required connections. The final arrangement is illustrated below. There are 3 unused decoder function outputs (green, yellow and brown wires) where leads have been shortened, but are still accessible for (unlikely) future use.
The availability of new and upgraded components has initiated a major update of the website. New versions of Home, Radio Control and Battery Power pages are already online and others will be published as editing progresses. Here are a few areas with significant new information.
New versions of S-CAB radio receiver (LXR) and Battery Power Supply (BPS) are available
LXR: The new receiver board is designed for convenient integration with new decoders. Another design change involves antenna placement. After several years experience with various antenna orientations, the new LXR standardizes cross-wise mounting as shown in the photo. Vertical mounting is still available by special order, but horizontal (lengthwise) is discontinued, since it offers no performance advantage and increases overall length of the receiver.
BPS: A complete redesign of the Battery Power Supply provides major improvements:
New decoders, which simplify S-CAB installation, have been selected as standard products for S-CAB systems.
Decoders referenced in this blog are manufactured by NCE Corporation and SoundTraxx respectively.
Product names, trademarks, copyrights and other proprietary rights of these companies are acknowledged.
NCE recently released D13DRJ, a new version of its popular D13 series HO decoders, which is intended for use in battery powered, radio controlled models. "DR" is derived from "direct radio" and "J" means it has an NMRA standard 9-pin JST socket and wire harness. The radio is compatible with S-CAB and battery power can be a BPS battery power supply or a series-connected, multi-cell (typically 11.1 or 14.4 volt) battery pack. One side of the circuit board is the decoder, which has been simplified and reduced in size by removing rectifiers that are required for DCC track input, but unnecessary with battery power. A Linx Technologies radio receiver, mounted on the second side of the board, provides DCC commands directly to the decoder microprocessor; the same method as used by S-CAB. The remaining radio-side components form an electronic on/off battery switch. The blue wire is an antenna. (A 3 inch length of wire makes a simple antenna.)
Using D13DRJ with S-CAB
The decoder is "plug and play" when used with S-CAB radio and a battery pack. However, decoder red and black leads are no longer DCC track input. Red is battery positive and black is battery negative. Correct polarity is critical.
Simple modifications are required when used with BPS battery power. The battery switch included in the decoder is convenient when using a battery pack, since it eliminates the need to mount a separate switch somewhere in the loco. Battery power is turned on with a magnetic wand and turned off with a command to the decoder. However, this duplicates functionality already included in the BPS and would not prevent BPS battery discharge, since the BPS battery connects internally to a step-up converter, which produces the 12 volt output.
There a two ways to eliminate the confusion of duplicate switches. Either disable the electronic switch by putting it in a permanently 'on-state' when there is battery power, or remove the switch and replace it with a wire connection.
I'll illustrate removal for this blog. It's simple, but not reversible. All components except the radio are removed and the chip that forms the electronic switch is replaced with a wire.
The always-on modification suggested by NCE is slightly more complicated, but is a reversible procedure.
S-CAB users can order the D13DRJ decoder now at the same price as an S-CAB-compatible D13SR or D13SRJ. I'll add it to the price list page once I decide whether or not it replaces D13SRJs. It's a neater, smaller, easier to install solution for users who prefer non-sound decoders or are working with restricted space in small locos.
For S-CAB use, I've added a ceramic antenna with a healthy dab of epoxy to reinforce the very weak solder connection. Horizontal or vertical mounting is available and both orientations provide excellent radio reception.
NCE decoders sold by me for S-CAB use now include a firmware version that supports use of function F5 for turning off battery power and eliminates the requirement to use a separate switch or sensor for this purpose. This is part of an effort to "standardize" F5 as a battery-off command. However a switch can still be used if that is the user's preference.
I thank NCE for cooperation during this development and willingness to bring what may remain a niche product to market. As always, NCE's proprietary rights are acknowledged.
Two new Walthers ALCO DL-109 HO-scale locos will be converted to S-CAB radio control and battery power for operation as a permanent consist with number 759 as the lead loco (the A unit) and 749 (B unit) running backwards. An identical set of components will be installed in each loco and the 2-loco consist will be operated by giving each loco the same decoder address.
When buying locos for S-CAB installations, it's best to avoid factory-installed decoders and we begin this project with a "DC version" Walthers model. Although it is marketed as DCC ready, this loco is not DCC friendly. A circuit board to accommodate a decoder is provided above the motor, but there is very little clearance between a large metal casting that forms the model's frame and the underside of the loco's roof. Removing part of this casting is the only way to create space for battery and radio components. This requires complete dis-assembly of the loco and, although this may seem like a lot of work, it's not very difficult and provides a more orderly way to perform an installation. The mass of metal that forms the loco frame is photographed below.
Modifying the loco frame
There are only three locations where removing metal can provide useful space:
There are five components to install, three of which significantly affect space requirements. The BPS circuit board is fixed and the TSU-1000 decoder is required to safely handle power requirements of this heavy loco. This leaves battery, radio receiver and speaker for which we have options.
Here are a few considerations that led to the final arrangement illustrated below.
The radio receiver is mounted at front of loco and part of the frame is cut away for two reasons:
The speaker is glued to a styrene plastic mounting that is attached to the frame with screws, which allows assembly to be removed for access to drive shaft and front truck. To complete this sub-assembly, the radio receiver will be mounted on back of speaker enclosure with adhesive or double sided sticky tape.
The BPS is installed at the rear of the loco where it sits in a plastic mounting attached to the loco frame with screws so that the rear truck is accessible. By using 1/8" styrene, the two largest BPS components (inductors) are almost flush with the lower surface of the plastic mounting. There is also a spacer below the mounting so that the BPS magnet sensor is positioned close to the loco roof.
This arrangement leaves space above the motor for battery and decoder, neither of which is sensitive to the motor's magnet.
Tweaks to reduce component size
The BPS is delivered with holes for wire stress relief to prevent breaks at soldered connections, but this precaution can be abandoned to shorten the circuit board by about 1/8".
Eliminating battery socket and direct wiring the battery connection is another space saver. Wire both battery and BPS with leads an inch or more in length, then solder and insulate to join leads as the last step in making the connection. This reduces the risk of accidental short-circuit while working with a charged battery and also provides extra wire to simplify battery replacement, should this become necessary.
Tweaks to fit components in available space
Completing the project
There is nothing quite as frustrating as completing, testing and tidying up wiring, only to discover the loco's body shell will not fit with everything installed. To avoid this disappointment, it's best to perform several trial fits of the shell with various combinations of components temporarily held in place with electrical or Kapton tape.
Components should be bench tested before installation and retested as each subsystem is installed and wired. This includes a test to be sure motor polarity is wired correctly and noting for this installation that loco 749 will be running backwards when the consist is operating in forward direction. It is therefore convenient to wire its motor with reversed polarity relative to the lead loco (759).
Setting up the consist
As mentioned earlier, locos will be coupled back-to-back to form a more or less permanent consist. Since the locos are mechanically identical and their speed characteristics are similar in each direction, no speed curve matching is required and respective motor control CVs will have identical values. Configuring function outputs is easy, since a headlight (function F0) is the only loco feature to be controlled. One other function output, F5, will be used to turn off battery power.
Assigning the same decoder address to each loco, avoids the need for a separate consist address. Each loco's decoder, having the same address, will respond to a radio command for that address. The only reason to set up a consist address is a requirement for each loco to respond differently to the same command. This also applies to CV programming commands and is the reason loco 749's motor was connected with polarity reversed; it runs backwards in response to a forward command. A similar result could be achieved using CV29, but this requires the decoders to have different values for CV29. Except for the bell (which is set to zero volume in 749), both locos have identical values for all CVs.
With radio control, no programming track is required and, once the decoders have the same address, CVs are programmed simultaneously for both locos, using either operation or service mode programming. To set a CV value (for example, the bell volume) for only one of the locos, just turn off the other's battery power. If using service mode programming, be sure to turn off power for all other decoders to prevent them from responding to a globally addressed command.
To separate the consist and operate as separate locos, the S-CAB throttle can be used to change the address for one of the locos. If desired, CV29 can be programmed (using the S-CAB throttle) to reverse motor polarity of loco 749.
The consist is operated in the same manner as a single loco. Momentum settings should be the same for each loco with values that match acceleration and braking somewhat realistically with diesel engine exhaust sound. This can be done by using the S-CAB throttle to adjust the values of CVs 3 and 4.
Except for one operating scenario, decoder default settings operate headlights automatically. F0 toggles headlights on and off. With F0 on and loco 759 moving forward, its headlight will be on and 749's will be off. However, if the consist is backing a train into a station or siding, 749 will be shining its headlight onto the end of the nearest car. Operation will be a little more realistic if F0 is used to turn off headlights.
Battery power requires a method to turn batteries on and off. If the consist is on powered track, turn-on is automatic when BPS detects track voltage. If track is not powered, a magnet held close to the on-board sensor turns the battery on manually. With some wired connections between locos, both could be turned on using one loco's sensor. However, it's simpler to just turn on each loco separately (so long as we remember to do it).
If there is no track power, a decoder F5 command turns off batteries of both locos (since their decoders have the same address). Function commands toggle decoder outputs on and off. It may not seem intuitive, but turning F5 on, turns battery power off. However, the presence of track voltage overrides decoder F5 output and keeps battery power on. This can be the basis of a useful procedure as follows.
Look carefully and you may notice a pair of diodes added to the BPS. This allows output from the BPS to be supplied from two sources;
The diodes supply BPS output from the source with higher voltage. Since the step-up converter produces 12 volts, BPS output is supplied from the battery until the rectified supply to the BPS exceeds 12 volts. In logic terms, the diodes form an "OR" circuit; only the greater voltage appears at the output.
No track power: If there is no power to the BPS (for example, a loco is operating on unpowered track), BPS output is produced using energy from the battery. With no power source for recharging, battery storage determines how long the battery can power a loco.
DCC track power: Suppose DCC voltage is 13.5 volts (27 volts peak to peak). When rectified, the resulting voltage will be approx. 12.5 volts and will supply the BPS output from DCC with little or no energy being used from the battery. If the DCC voltage drops or is interrupted, the battery instantaneously supplies the output until DCC voltage recovers. The loco keeps running, the decoder does not reboot, no stay-alive capacitors are required.
Recharging: Suppose there is power connected to at least part of the layout. Whenever voltage input to the BPS exceeds 5 volts, the BPS battery will be recharging. This is true whether track is powered with DC, AC or DCC.
Why is this an Upgrade?
Since it has always been possible to use the BPS with the foregoing benefits, why does adding a couple of diodes qualify as an upgrade?
It simplifies wiring by eliminating the need for primary and backup configurations. Two wiring diagrams on the applications page will soon be replaced by the diagram to the right.
A loco to be equipped with S-CAB radio control and battery power will be wired the same way, irrespective of whether the layout has complete, partial or no power supply to the track. Readers familiar with BPS may notice that this wiring is actually the original "primary connection". In other words, the backup connection diagram is unnecessary and will be eliminated.
Most BPS installations have used the primary connection and are not affected by this upgrade. Installations wired with backup connections should be left as they are unless there is some reason to change the BPS circuit board.
To distinguish new and old BPS boards, look for the added diodes. This is not a new version of the BPS circuit board. It's simply the existing design with a capacitor removed and two diodes added.
One More Benefit
There have been examples where a battery becomes over-discharged and will not recharge unless disconnected from the BPS. This can happen when a user repeatedly attempts to restart a loco with a battery that is 3 volts or lower. The BPS typically shuts down when battery voltage reaches 3 volts, but the battery protection module does not disconnect the battery until voltage drops to 2.7 volts. Between 3 and 2.7 volts, the battery may or may not recharge while attempting to supply the step-up converter. The upgrade eliminates this problem by removing any step-up converter load on the battery whenever input voltage (being used to charge the battery) exceeds 13 volts.
Converting this loco to S-CAB radio control and battery power supply is a relatively easy project. Since there is plenty of space, I devoted extra effort to building a framework out of styrene plastic to hold electronic components and battery. A SoundTraxx TSU-1000 sound decoder, the S-CAB radio receiver and the BPS battery power supply will sit on a shelf above the motor. Two 850 mAh batteries will be mounted on edge; one each side of the rear truck assembly.
Removing 4 screws and the front coupler allows the loco body to be removed from the chassis. The rear truck-mounted coupler does not obstruct removal of the body shell. Each truck is secured by a self locking nut, which, when removed, allows the truck to drop from it's mounting. In the photo below, I've also removed drive shafts as well as some wiring for track power pick-up and headlight. The die-cast metal frame is simple and functional, providing a good foundation for constructing some plastic framework to keep the rest of the installation tidy and secure.
The entire installation is two assemblies; battery power supply and batteries at the rear of the loco chassis; decoder, radio receiver and speaker in the middle and the loco cab is left unobstructed except for a frame (to mount a marker light) that is barely visible above the cab windows. For easy access to motor and drive shafts, the plastic framework is mounted with screws accessible from underside of the loco. The retaining nut for the rear truck can be adjusted by moving the BPS circuit board out of the way.
I forgot to remove the blue masking tape when taking the photos below, but it's something I do quite frequently to keep unruly tangles of wire under control during assembly. Paint masking tape has the advantage of being sticky enough to hold wiring out of the way and does no damage when being removed.
Since batteries don't last forever, it's best if they are accessible, as illustrated in the photo below. The BPS circuit board should be mounted so that the magnetic sensor is close to roof or side of the model where it can be activated by a magnetic wand/pencil. If the BPS board must be buried deep within the model, the sensor can be removed from the board and glued to the model's shell with wiring back to the BPS.
Below is a view from the front of the loco showing the factory installed headlight, which I've wired with a 4,700 ohm series resistor and connected the the decoder headlight output (white and blue leads). I've also added a small surface mount LED as a marker light (also with a 4,700 ohm resistor) and powered directly from the BPS 12 volt output. It's primary purpose is to indicate when battery power in turned on. Sound from the decoder will also confirm power is on, but not if sound has been muted.
Barely visible below the radio antenna is a model DS1425-8 speaker from RailMaster Hobbies. It's already assembled in an enclosure (16x27x9 mm) and produces very good sound for its size.
Testing and Tweaking
A neat aspect of this assembly is no components (e.g. lights) are mounted on the loco shell and therefore, there is no wiring between chassis and body of the model. All testing and initial programming of decoder CVs is done before closing up the model.
Operating Tests: Since Tsunami CV default settings are compatible with S-CAB, initial test runs are done before adjusting decoder Configuration Variables (CVs). Since I'd previously checked BPS operation, I began this running test with no track power and turned on battery power with the magnetic sensor. Using an S-CAB throttle and factory default decoder address "3", the loco moved slowly at speed step 1, direction control operated correctly, headlight control worked as expected, sound volume was good, and function output F5 turned off battery power as planned.
Battery charging: For this test, I connect a variable voltage DC power supply with current measurement to the rails and slowly increased voltage while watching current measurement. At about 5 to 6 volts, the decoder came to life and the marker light indicated track power has been detected. Current reading (typically about 200 to 400 mA) confirmed battery was charging. When DC power supply to the track was switched off, decoder and marker light continued to operate on battery power. All was good.
Decoder CVs: The basic decoder CVs can be programmed with an S-CAB throttle using broadcast mode. This requires that the "ALL" key be pressed immediately after switching the throttle to CV mode. I set CV values as follows:
CV1, decoder address, new value "6"
CV2, minimum speed, new value "1"
CV3, acceleration, new value, "20"
CV4, deceleration, new value "20"
CV5, maximum speed, no change
CV6, mid-speed, default value, "0"
CV29, decoder configuration, set to S-CAB default value "0" (The actual value stored in the decoder is "2")
Replacing the loco body: In this case, the body shell slips over the fully wired and tested chassis. Before attempting this, I used electrical insulating tape to tidy up any wiring likely to cause problems by getting stuck as the shell is maneuvered over the plastic frame holding the components. This is also the right time to make sure all wiring is properly insulated.
Once the loco body is securely in place, there is one more check to be sure the magnetic sensor is located close enough to the underside of the loco hood to reliably detect the magnetic wand. (Magnet actuation range is between 0.375 and 0.5 inches.)
Load Test: I performed this test with track power on. The idea is to prevent loco movement without applying pressure that artificially increases traction. The objective is to measure current consumption at the point where the loco loses traction and wheels begin to slip. This loco has plenty of traction; I had my hand blocking forward motion and the loco simply slide the track across my workbench. With track secured and the loco wheels slipping, current consumption was approximately 800 mA. This is right at the short-term overload capability of the BPS when operating on battery power. However, without the assist of track power, BPS current limiting would automatically lower voltage to reduce load and prevent BPS overload.
Narrow hood loco models with heavy metal castings are difficult candidates for battery power and radio control. This Life-Like Models GP9 is a classic example. It's assembly is simple; basically three sub-assemblies held together by a few screws. Remove couplers, undo 2 screws and the plastic shell lifts off in one piece. Undo 4 more screws and a large die-cast molding lifts off the chassis. This metal casting is designed to fill available space and maximize loco weight. Fortunately, it's robust and nothing is directly attached, so there is minimal risk to removing metal from top of the casting to create space flush against the roof of the engine hood. The objective is to remove a little metal as possible so as retain enough weight for reasonable traction.
A non-sound decoder will be used for this installation, although a sound decoder could be used if more metal is removed to make space for a speaker. However, further reduction of weight is not desirable unless sound is a high priority.
This is all neat and tidy. No work is required except replacing motor and track power connections with more flexible wires that are less likely to fatigue and break as I struggle with reassembly.
Carving (machining) a flat top surface on the metal casting creates space and provides a convenient mounting for battery power and radio control components. Electrical insulating tape is used between components and bare metal as well as holding everything in place. Since the metal casting is a snug fit in the body shell, there is no room for wires between the casting and sides of the body housing. The only space for wiring is between top of components and hood roof.
This photo shows arrangement of components with wiring complete except for front and rear lights (white, yellow and blue leads). LEDs with series resistors are already mounted in the body shell. With so much metal, I was concerned about radio reception and mounted the radio receiver with antenna at front of the loco above the driver's cab. The battery is above the motor and battery power supply at the rear of the loco. The narrow hood limits battery choice to 550 mAh storage, smaller than I would prefer, but probably adequate given the motor's low power consumption and the fact that most of the owner's layout is powered. The BPS has also been trimmed by removing wire stress relief holes and eliminating the battery plug and socket by wiring directly to BPS terminals.
It has become common practice for manufacturers to use clear plastic light diffusers or light pipes for loco lights. To save space, I use a tiny surface mount LED glued directly to the diffuser or light pipe with clear epoxy cement. I also use warm white LEDs instead of the more readily available blue-white LEDs that are totally unrealistic representations of loco lights. With a 12 volt supply, I use a 4.7 K-ohm series resistor, which means the LED current is about 2 mA.
Battery On/Off Switching
The battery turns on and stays on when track power is detected. A magnet (mounted on a pencil) and two magnetic sensors are used to manually turn battery power on and off. Since a sensor's activation range is about half an inch, (I aim for about 0.375" to make sure switching is reliable), it should be mounted as close as possible to top or side of the loco shell. The "on" sensor is already included on the BPS circuit board. I generally mount the "off" sensor on or near the radio receiver because the radio antenna is best located as far away from the motor as possible. This same precaution applies to the sensor because the motor's magnetic field will falsely activate the sensor.
The purpose of this post is to publish some videos showing progress toward our objective. I say "our objective" because this has been a cooperative effort with an S-CAB user, whom I will call "Bill". It is work in progress and these videos, taken on my workbench using a cell phone, are not intended to be sophisticated little movies.
Until now, a search of this S-CAB website for "Titan" (use the search box at top of the page) produces an obscure reference on the Price List page. It has remained obscure because there's not much demand for Titan. However, Bill has persisted with great patience and tenacity. It began mid-2011, when he noticed QSI was replacing their then-current sound decoder (Revolution) with a new product called "Titan".
Bill purchased and sent Titan to me as soon QSI began delivery. By July, 2011, with some help from QSI, I converted Titan for use with S-CAB and battery power. This decoder is a very ambitious product; both in terms of functionality and technical complexity, which makes it difficult, both for me as I work on S-CAB radio control and battery power, but also for users trying to install the product. I thought it premature at this early date to publicize S-CAB compatibility. I had no experience installing or operating a loco with Titan. Bill was busy testing S-CAB (with Tsunami) and BPS power in one of his locos and did not follow up immediately with a Titan order.
However, an order for S-CAB with Titan did come through Northwest Short Line (NWSL) from a purchaser with computer programming experience. I mention this because this client dragged me reluctantly into providing S-CAB support for programming Titan CVs. With professional programming experience, he did not require me to get involved with actual programming of Titan CVs. Consequently, I was not well-prepared for the full scope of a Titan installation.
Let's See Some Action
In each of the following videos, Bill's loco is operating with BPS battery power. No power is connected to the rails. A Titan decoder is controlling the loco in response to operator commands transmitted by radio directly from the S-CAB throttle to a radio receiver in the loco. All loco system components, including BPS and battery, are installed in the tender. An S-CAB throttle is the only other device used in these videos (excluding my cell phone).
This experience has me thinking about decoders and loco control from a new perspective. As a loco operator, all I can do is use available controls so that the loco does what I want, within the constraints of its design. I can't command a steam loco to perform like a sports car. A decoder should be configured to reproduce physical constraints of the loco model's full size prototype. It's not important whether the throttle uses 28 or 128 speed steps. I can whip the throttle to full speed with a flick of the thumb and the loco simply accelerates at a maximum rate allowed by the decoder. If I whip the throttle back to zero, the loco slows with prototypical realism if CV4 has been set appropriately. An elegant feature of Titan is it's capability to operate braking separately from throttle control. Just quickly move throttle to zero and use a function button to manage brakes. This capability is not unique among sound decoders, but braking sound effects are handled quite convincingly by Titan.
I acknowledge that many layouts are not big enough to operate steam locos operating in prototypical fashion, but keep in mind these videos show an S scale loco operating on six feet of track.
This is not journey's end, but I'm now convinced that Bill's persistence has been justified.
I'm a retired electrical engineer, but still spending more time on engineering than on my layout. These days, it's mostly about applying radio control and battery power on smaller scale layouts (HO, On3, On30)
The photo above is not my layout. It's a great view of Seattle's King Street station by Ross Fotheringham.