Bay Area Garden Railway Society

Electronics for our battery-operated locomotive

12/06/2010 8:16 PM | Anonymous member (Administrator)

For this project we wanted a train with a simple, inexpensive control system capable of operating on no-powered track. The solution we adopted uses a 9.6-volt NiMH (nickel metal hydride) rechargeable battery available from Radio Shack and other sources. This battery fits into the engine cab and operates our small LGB locomotive for over four hours on a single charge. The battery uses a standard hobby connector making it easy to install a fresh battery when needed.

While there are many radio-control throttles available on the market, we did not need speed or directions control for the display layout train.  A small ON/OFF radio-controlled receiver with relay similar to those used for automotive alarms gives us the ability to start and stop the locomotive with a small remote control. Our remote control is catalog item number RC-10 from All Electronics Corp., This firm sells manufacturers production overruns and surplus inventory so we can’t guarantee that this particular item will be in stock in the future. However, similar remote controls are designed to operate on 12 volts DC, but the RC-10 receiver works on the 9.6-volt battery.

Figure (photo 1) shows the circuit arrangement. The mating connector used to connect  to the battery is also available from Radio Shack. Since these batteries can deliver a high current when short circuited, we included a resettable circuit protector, sometimes called a polyswitch, to protect the battery. This circuit protector is available from All-Electronics as item #CPX-100S. A two-amp fuse could be substituted for the circuit protector.

The locomotive motor must be disconnected from the normal connections to the wheels and current pickup sliders. For our LGB locomotive, we removed the gearbox bottom cover plate and the removed the sliders and brass strips that carry current to the motor leads. This disconnected the motor from the rails. LGB locomotives include small sockets on the cab rear that connect to the motor brushes. We used these sockets to connect the output of the remote relay (battery positive) and battery negative to the motor.

Now, pressing the remote’s ON button operates the relay and makes the locomotive go forward at full speed. Pressing the OFF button releases the relay and stops the locomotive. In our case, the locomotive speed is fine with the 9.6-volt battery. If the speed were too fast, we could have inserted one or more silicon diodes (All Electronics #1N4001) in series with the motor leads to reduce the voltage by 0.7 volts for each diode.

Kermit Paul

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