Several emails have been received concerning closure of NWSL and possible impact on S-CAB and Stanton Drives.
S-CAB is not part of NWSL and its listing on www.nwsl.com is basically a link to www.s-cab.com. Inquiries about S-CAB have been routinely redirected to Neil Stanton. Future inquiries should use this S-CAB website.
These drives have always been manufactured and sold by NWSL. They are designed by Stanton but are not an S-CAB product and will not be offered as such on the S-CAB website. Plans are underway to continue their manufacture in Montana by a spin-off organization staffed by the same individuals who currently build and test these products. How they will be sold after NWSL is closed has not yet been determined, but end-user sales are likely to become a "direct-sale only" item managed by Dave Rygmyr, who will also continue to be responsible for OEM sales. As inventory is replenished "NWSL" will fade away, but "Stanton Drive" is protected by copyright and will not change.
The motherboard concept has been discussed elsewhere. It is intended to simplify installation of an S-CAB battery powered, radio-controlled system in small-scale locos. The purpose of this document is to report its application in a HO-scale Atlas-Kato GP-7. For brevity, we’ll skip the details and go directly to the result.
Ready to roll
This loco is ready to roll. All it needs is a body shell, which slides over the installation onto the chassis without much effort. It’s shown naked and annotated as an introduction to use of an S-CAB motherboard.
For this installation, all components are mounted on the motherboard, including loco’s lights. This arrangement is a convenient characteristic of a GP-7 and other high-nose diesels. Consequently, no wiring connects to the body shell.
The motherboard assembly is completed and tested on the workbench. It is then mounted on the loco chassis and permanent connections made to motor and truck wheel wipers. Additional tests are completed before replacing the body shell. For example, does the forward direction command cause forward motion and operate the headlight.
No need to replace the body shell for a work-bench test-run. No need for track or power. Just turn on BPS battery power using a magnet wand and the loco (with or without shell) is ready to roll but be careful it does not end up on the floor.
Aside from running off bench-top, this is a low-risk test. The motherboard was tested before making chassis connections and there is no external power source to cause trouble.
A track test is higher risk. First, try it with no track power, which is not much different from a bench test, except the loco can be operated more thoroughly if its battery has enough charge. To test battery charging, turn on track power. This is the step where serious trouble can occur, which is a good reason to do it without the body shell. Common mistakes are forgetting to isolate motor terminals from loco frame, bad choice of power supply, shorted truck wipers, etc.
A green LED on BPS-v4 indicates if battery is charging. It's not obvious because the green LED is on the underside when BPS is mounted on the motherboard. The BPS is oriented so that reed switches are topside where they can be activated by a magnet wand. Another good test is turn off battery power (blue LED off) before turning on track power. BPS starts automatically when track power turns on.
This is a critical step in any installation. Will the lid close? The motherboard helps by enabling test fitting more easily throughout the project. Wiring clutter is eliminated, components don’t rearrange themselves by accident, and tight spots inside body shell can often be trimmed. The most difficult issue is headroom. Is there enough clearance above the loco’s mechanism for the motherboard assembly? This question must be addressed when planning an installation.
Good news. The lid fits.
The following components are mounted on the motherboard:
Battery replacement: The battery is best secured to the motherboard by a removable method that does not leave a mess to clean up. Kapton tape is good and leaves no residue. Double sided adhesive tape is not recommended. When freed, lift the battery and lever its plug from BPS socket with tweezers or needle nose pliers. Since the battery leads are deliberately short (about ¾”) and the plug is tight, pulling by the battery may remove the battery and leave its plug stuck in BPS socket.
If the loco’s mechanism needs maintenance, unsolder motor and truck pickup connections from the motherboard. If glued in place, there are 2 locations to pry loose and the assembly lifts off as a unit. If held in place by Kapton tape (author’s preference), cut and/or peel off the tape to remove the assembly.
This installation was performed by John Lloyd in four identical models for a Canadian customer. The motherboard was designed to fit the GP-7 as well as a popular selection of North American diesel-electric locomotives. EMD GP, F and E class locos are good candidates. As we gain experience, the motherboard may be provided as basic, partial and fully assembled versions.
What is a Motherboard?
A motherboard is a circuit board onto which various sub-units ("modules") are mounted. Connectors and circuit traces on the motherboard facilitate modularity and eliminate wiring between modules.
MB-GP-v2 fits a broad selection of HO scale, US style diesel-electric locos; EMD GP series, for example, often called "Geeps". It measures 0.67” wide, 5.75” long (17 x 146 mm), which is small enough for a GP-7 installation, yet large enough to accommodate a complete battery powered, radio controlled, ready-to-run system using commercially available DCC sound or non-sound decoders.
In addition to mounting BPS battery power supply, battery, radio receiver and decoder, the board includes terminals for external connections; track power pick-up, motor, LED lights and speaker. Depending on loco, lights and speaker can be mounted on the motherboard, which eliminates wiring connected to loco’s body shell and requires only 4 connections (power pick-up and motor) to loco chassis/frame.
A 9-pin JST connector is provided for decoders with NMRA-compliant socket. No wiring harness is required. Decoders without a compliant JST socket require soldered connections and careful reference to decoder documentation. The BPS-v4 battery power supply can be mounted directly on motherboard (as in photo) or with a wired connection.
Add a decoder: This motherboard version requires either a SoundTraxx or NCE decoder with integrated S-CAB receiver. As shown in photo, no wiring is required for a SoundTraxx TSU-2200 decoder; just plug it in.
Plug in a battery: Depending on loco's space, 420, 800 or 1000 mAh batteries fit on the motherboard. If clearance between top of motor and roof interior permits, a 2P battery may be possible. However, 1P and 2P-420 are the only choices for HO scale, narrow-hooded GPs. The following photo includes a 1P-420 battery. Note the 3/4” battery leads, which will be default choice for batteries included with a motherboard installation.
For HO models, application depends on the model’s prototype and its manufacturer. S-scale modelers should find the motherboard an easy fit. Fully assembled with a 1P-420 battery, the motherboard requires 0.44” (11.2 mm) headroom. Allow 12 mm (approx 0.5") clearance if using a 2P-420 battery.
Models with limited headroom, motor mounted high on the chassis, for example, are not good candidates for this motherboard. Small yard switchers (SW series) in HO scale can also be eliminated as candidates. This still leaves a large selection of diesel prototypes for which this motherboard is applicable. However, creating unobstructed space can be a challenge. Factory installed circuit boards, over-sized metal castings, light-pipes, existing wiring and other clutter may have to be removed.
Example - Atlas-Kato GP-7 Installation
This example used version 1 of the motherboard. No modification of loco chassis was required. The shell required some work. Light pipes were removed and interior of body shell decluttered. Lights and speaker were mounted on motherboard.
The lens portion of light pipes was retained and glued into body shell.
Components used: TSU-1100 decoder, S-CAB radio receiver, 1P-420 battery, BPS battery power supply, mini-cube speaker, LED headlight and rear light.
NCE and SoundTraxx manufacture decoders referenced in this blog. Their proprietary rights, including product names, is acknowledged.
Effective October 31, 2018, we introduce two new battery sizes and phase out BPS-300 and BPS-500 batteries.
This is the battery of choice for HO-scale narrow-hooded diesels (GP series, for example). It replaces BPS-300 and BPS-500 batteries which will be discontinued.
This adds a larger cell to the BPS battery range. It is intended for use in steam loco tenders and in S-scale diesel locos.
There is no change here. This is the most popular BPS battery used for HO-scale full-width diesels (E and F series, for example) most steam loco tenders and all larger scales (On30, On3, S). The new BPS-1000 is expected to replace it in some of these applications.
The 300 mAh cell is no longer available from manufacturer and is replaced by higher capacity 420 mAh cell which is same width and half an inch longer. The BPS-500 cell, which has been sourced from a different supplier, is replaced by the 420 so that all LiPo cells can be purchased from the same manufacturer.
Each cell size will be available as 1P and 2P back-to-back assemblies. Integrated fuse protection is standardized at 6 amps to be compatible with latest version of Battery Power Supply (BPS-v4) which requires up to 4 amps battery current at full output.
"P" indicates cells are connected in parallel. Voltage is same as single cell (nominally 3.7 volts) and capacity adds so a 2P-420 battery provides 840 mAh.
25C indicates cell is rated for high discharge; specifically, 25 times cell capacity. That is, 25 x 420 mA equals 10.5 amps from one cell and 21 amps from 2 cells in parallel. This should remove any doubts regarding the importance of embedded fuse protection.
When a back-to-back arrangement is too thick for some applications, cells can be wired with an arbitrary length of wire between them. With the arrangement illustrated (right) cells share one fuse as is done with a back-to-back assembly. However, this leaves one cell with external wiring and no internal protection. Although the risk is low, this practice will be discontinued.
In future, separated 2P arrangements will use two 1P batteries (each with fuse) connected in parallel. One precaution with this arrangement is make sure cell voltages are approximately equal before connecting. The equalizing current surge created by a large voltage difference may be sufficient to blow one or both fuses. Be sure to connect positive to positive.
This fourth generation BPS power supply is intended for on-board battery power installations requiring up to 1 amp from a package small enough for installation in HO, On3, On30 models. It's also a good choice for S scale models with efficient can-type motors.
6 amp Battery Fuse
Batteries for previous versions of BPS included a 3.5 amp fuse and used insulation displacement battery plugs.
At 1 amp load, BPS v4 consumes up to 4 amps from the battery, which requires a 6 amp battery fuse, heavier leads and a crimp-style plug.
Over-voltage and short-circuit protection
The protection block in the above diagram protects against three abnormal conditions.
Decoder Off command
By default, S-CAB installations with SoundTraxx or NCE decoders are set up to use a decoder ‘F5’ command to shut down battery power. This requires connection of the BPS shut-down wire (brown) to the appropriate decoder function output as shown in the above diagram. For SoundTraxx, this is a brown wire (output FX4); for NCE decoder, the wire color is purple/violet.
BPS as a general source of on-board power
If a locomotive or traction model needs on-board DC power, BPS can do the job so long as demand does not exceed 1 amp. Temporary overloads up to 1.2 amps are okay. Standard output voltage is 11 volts, but can be customized within a range from 9 to 12 volts.
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.
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.