Dec. 2020: A Short NEM Motherboard
S-CAB MB-GP-NEM-S is a motherboard (MB) for HO scale, narrow-hood (typically GP locos), using decoders with 21-pin NEM sockets. “S” is the short version, which, unlike the original (long) version, does not include battery space on the motherboard. The important measurements are 3.3” long, 0.7 “ wide, and 0.41” at thickest point.
July 2020: A Motherboard for NEM Decoders
Here is a new diesel loco motherboard to support decoders which have a 21-pin NEM socket. It's the second member of what may become a family if the concept is popular with S-CAB users.
MB-GP-NEM is a circuit board which assembles battery power and radio-control components as a ready-to-run installation. Most wiring is replaced by motherboard circuit traces, which provides a neat installation, less soldering and fewer errors.
2019: Introducing S-CAB Motherboards
The first motherboard was developed last year for decoders with a 9-pin JST socket and is discussed in two blog posts.
Jan. 2020: BPS-Lite
BPS-Lite is intended for mobile lighting; specifically, coaches and cabooses. It includes a bridge rectifier, battery charger, 2 LED light outputs, an on/off switch and a connection for battery output. There are two indication lights on the circuit board; a green LED lights while charging; a white LED indicates lights are on. Two magnetic reed switches on back side of board are used to switch battery and light outputs on and off.
Visit this link for Peter Vanvliet's description of his caboose installation.
Dec. 2020: Introducing a 1200 mAh Battery
The 1000 mAh cell will be discontinued and replaced by this new 1200 mAh cell. Like the 1000, it is 30 mm wide, which fits well in typical steam loco tenders. It is available as either a 1P and 2P battery with 8 amp fuse protection.
S-CAB Radio Control
April 2020: Version 2.5 Firmware Upgrade
The upgrade is distributed on a replacement microprocessor chip.
Install the upgrade as follows:
Jan. 2020: Throttle Upgrade
An S-CAB radio upgrade was completed and implemented seamlessly in both S-CAB throttle and S-CAB loco receivers. Since it is backward compatible with Linx Technology radio modules (now obsolete), the upgrade has no affect on existing users. Not only is this the best result for S-CAB users, it is a good choice for new users due to simplicity, lower cost and no dependence on network communications. Computers, phones and networks are not required.
About this Website
The purpose of this website is to encourage use of on-board battery power and radio control of locomotives (and similar traction equipment) modeled in HO, On3, On30, Sn3 and S scales. Combining on-board battery power and radio control eliminates all, or at least the most inconvenient aspects of, wiring and operating a layout. Eliminating dependence on rail to wheel electrical contact for both power and control significantly improves reliability of locomotive operation.
The style and content of this website aims to offer a model railroading resource that explains S-CAB as a system to implement battery powered, radio controlled HO-sized model trains. I've developed a set of components along the way and am happy to provide them at low margin to fellow modelers. However, selling merchandise is not the primary purpose of this website.
What do I mean by "model railroading resource"?
This website is for model railroad modelers and operators. I'm not an evangelist for new technologies or products. Quite the opposite; I'm an advocate for the simplest, most reliable, proven way to operate a model railroad. My objective is to evaluate if, and how, technology can improve model railroading enjoyment with minimum confusion and/or disruption.
For example, S-CAB does not reinvent model train control. It builds upon, and is compatible with, existing model railroading products and standards, including NMRA (National Model Railroad Association) standards for Digital Command Control (DCC). However,
S-CAB is not DCC, although it uses DCC decoders for loco control.
Why use DCC decoders?
Because they're mature products with comprehensive model railroading functionality produced in vast quantities by many manufacturers. Development costs have long since been recovered and economies of scale give overwhelming competitive advantage to established suppliers.
Communication to decoders is by radio?
Yes, for NCE and SoundTraxx decoders, the S-CAB receiver delivers DCC commands directly to the decoder's microprocessor. This is called a "direct radio interface".
What about other manufacturers' decoders?
A DCC Booster connected to an S-CAB receiver can deliver DCC through a decoder's right and left rail terminals. It's not as efficient as the direct radio interface, but works for most decoders.
Is a DCC system required?
No, A DCC system is not required. An S-CAB throttle transmits decoder commands directly to locos with S-CAB receivers.
Is S-CAB compatible with DCC?
Yes, track output from DCC command stations or throttles can be transmitted by S-CAB radio. It can also remain connected to track in order to operate locos without S-CAB radio. Where available, DCC track power can be used by S-CAB BPS for battery charging.
Can S-CAB be used with DC layouts?
The answer depends on equipment being used for DC control. If S-CAB BPS uses track power for battery charging, a well-filtered DC supply between 12 and 13 volts is an ideal power source. Unfortunately, many legacy DC voltage controllers deliver unregulated output with voltage peaks (spikes) that can damage electronic equipment. BPS-v4 can survive voltage peaks up to 35 volts, but it's best to avoid use of old DC loco controllers, especially models with labels such as "pulse power".
About this Update
It's 2020, and, as I work on this update, interest in battery power has moved from justification to application. S-CAB components have iterated through several development cycles, reached a stable level of maturity and accumulated a solid base of user experience. Today, the focus of S-CAB is to simplify application of battery power and facilitate its use in models that were previously considered too small for batteries. All aspects of safe LiPo battery management, including battery charging, is handled by an S-CAB BPS battery power supply.
Since battery power supply without reliable control risks a run-away train, S-CAB communicates by radio to prevent loss of control caused by intermittent rail to wheel contact, derailments and other interruptions of track power. An S-CAB equipped loco can operate on layouts with no track wiring so long as there are track sections for battery charging. However, since BPS performs battery charging whenever operating on powered track, greater use of powered track conserves battery energy and extends operating duration between recharges.
About the website name
As a self-contained, hand-held device for controlling model trains, the Stanton Radio Cab has been available for many years and during that time has acquired S-CAB as its abbreviated name. In choosing S-CAB.com for this website, I wanted continuity with S-CAB as a wireless controller while including more discussion of battery power in small-scale models.
"Cab" also has a broader connotation in railroad terminology. In real locomotives, cab is the compartment which accommodates crew and is the location from which they operate a locomotive. Planes have cockpits; locomotives have cabs. Hand-held controllers used to operate model trains are often called Cabs or throttles.
References to various manufacturers and their products are scattered throughout this website. Their proprietary rights, trade marks, copyrights, etc. are acknowledged.
S-CAB System Components
For a diesel loco, an S-CAB motherboard is the newest and easiest method of installation. Below is a complete S-CAB loco installation photographed during testing prior to delivery. I've added notes to identify S-CAB components and show how they are wired.
All components on the motherboard have been available in current versions for several years and used individually or in combination for a wide variety of battery power and/or radio control projects. Components have not changed. The motherboard simply eliminates wiring between S-CAB components. For example, BPS-v4 is mounted directly on the motherboard. The BPS battery (1P-420) plugs into the BPS connector using a 3/4" battery lead. Decoders with a standard 9-pin JST socket plug into a compatible connector on the motherboard. It's not obvious in the photo, but the S-CAB radio receiver is packaged with the decoder and requires no extra wiring.
BPS Battery Power Supply
S-CAB BPS combines a battery charger, battery management and a step-up voltage converter in one package.
It performs the following functions:
S-CAB Loco Receiver
An S-CAB loco receiver is a radio module packaged with a DCC decoder such as the SoundTraxx sound decoder illustrated above. One unique characteristic of S-CAB is direct connection of radio receiver data to the decoder's microprocessor. This shrinks the overall package (40 x 17 x 8 mm) and avoids inefficiency of alternative methods that waste battery energy by converting radio data to DCC power input in order to use the decoder's left/right track inputs.
A wireless, battery-powered, hand-held controller completes the S-CAB system. Communication is direct from throttle radio transmitter to a compatible receiver in the loco to which a command is addressed. Each throttle can manage up to 15 locos during an operating session. The radio transmits at 916.48 MHz, but is only active (approximately 0.04 seconds) while transmitting a command. Consequently, operating sessions with a number of participants and multiple throttles is possible. To date, the maximum is 6 throttles in regular use on a large layout.