How can an engine without a decoder run on a DCC layout?
It looks like magic but really it’s not. The DCC signal is symmetric around 0 volts. This provides a 0 volt DC component. By expanding the length of the zero bits on the positive side of the signal a positive DC component can be added. Likewise, by lengthening the bits on the negative side of the signal a negative DC component can be added. Only the 0 bits can be lengthened like this. The result is a non-zero average DC voltage that will run a loco without a decoder. However, since the complete signal gets to the motor, the stretched zero side causes the motor to run, and the following instant, the unstretched side (the opposite polarity) tries to reverse the motor. The longer (stretched) side wins, but motors do run more noisily and generate more heat. If you are using ironless core motors, you will need to take special precautions to avoid burning them up. Usually, a ballast lamp installed in the engine will do the trick. You should run these motors on the lowest possible voltage set
