If you assemble 10 modelers to discuss power and control for a model, you will come up with 20 different ways to do it. The cheapest method is to use batteries and a double pole, double throw (DPDT) switch with a center off position. This will provide a single speed forward and a single speed in reverse. Depending on the voltage you use, you may encounter some wheel spin when you switch the engine on.

One way to do this is shown to the right. I mounted a small DPDT switch on a bracket and soldered a piece of brass tubing with a hole filed in it to the bracket so that the arm of the switch sticks into the hole. Then I take another piece of brass tubing, one size smaller, drill a single hole into it, and slide it into the larger piece of tubing. The long piece of tubing becomes the exhaust stack and you either pull it up of push it down to move forward or backward depending on how you wire it.

There are lots of different batteries to choose from. Remember that we made the hood wide enough to fit two standard racing car 7.2 volt, NiCad batteries inside but a 12 volt gel-cell will also work fine and they come in lots of shapes and sizes that will fit. At a hobby shop that sells the NiCad batteries, you can also normally buy a wiring harness that hooks the two batteries together in series to give you 14.4 volts. Then it is just a matter of putting everything in place and you are ready to go outside, put the engine on the track, and send it on it's way.

But this forward-stop-backward control is really basic. The real solutions are to use track power or battery power with a radio controlled throttle. Very few in 7/8" scale use track power so I will address radio control. There are a number of good systems that can be fit into the engine along with the necessary batteries. Personally, I use the RCS system from Australia. I like it because the transmitter is very small and fits easily into the palm of my hand or my shirt pocket.

Another thing to consider is sound. Today's technology provides a number of manufacturers that make small electronic sound modules and, there is room for one of them inside the engine. But with sound, you need a speaker and for really great sound, the speaker needs to be enclosed in some sort of a speaker box. It would be possible to turn the hood into a speaker box or to construct one to fit inside the cab.

But there is still one more thing to consider and that is cost. Radio control and sound systems are not cheep and can cost from $300 to #500 depending on what you select. I have five engines now and I can't afford this much money for each engine. My solution? A trailer car! In fact, I have two trailer cars, one for the batteries and one for the electronics and the speaker. They all hook together with Miniatronics, 2 amp, connectors and I can plug any of my five engines into the battery cars that I choose, depending on my mood.

The photo below is one of my personal favorites and shows my battery and electronics cars behind a model of a 12 ton Vulcan.

Lets examine my cars. I decided to make two separate cars, but everything could just as easily fit into one small 4-wheel boxcar. The rear car above is the battery car. I took two standard NiCad batteries and built "wooden crates" around them with their connectors sticking out one end. I built a third crate to hold the wiring harness that hooks the batteries up in series, a fuse, and the charger for the RCS radio Control system. This was the first time I used the RCS system and I had no idea how long the battery charge would last. The RCS charger takes overnight to charge the batteries so I made them removable so that I could quick-charge them with a model car charger if I needed to. This turned out to be wasted effort. The two standard NiCads last for about 2 ½ hours of running which is more than enough. So if I had to do it over again, I would put everything into one car.

But remember that I said that a good speaker box is important. Well, my electronics car below shows what I did. I used a large speaker from Radio Shack and it is located on the front of the car, facing down, right behind the engine. I built a "crate" around the speaker which provides excellent sound. The left or rear end of this car holds another "crate" which contains all of the electronics. On the lower left in the photo, just above the rail, you can see the Miniatronics connector. I leave the male ends of the connectors hanging out of the rear of my engines and cars. I recessed the female ends into the front end sills of the two trailer cars. The wires are unobtrusive when connected.

So that’s it 7/8ers. The engine is finished. The basic engine can be built for less than $100 is you have odd bits and pieces of plastic and stuff laying around. The big two expenses are $50 for the motor block and $20 for the SVE wheels. I hope you will consider my method of batteries, control, and sound in a separate car. This will allow you to keep building small crittery engines without having to buy new electronics for each engine.

Happy Modeling

Jim Massfeller