The circuit that you are looking for is in the November 1979 RMC, page 64. This is an easy circuit to build, since even I have built one. Basically, get a piece of copper foil board from Radio Shack, along with eight one-amp diodes such as 1N4001 (Radio Shack part 276-1101), two 1.5 volt grain-of-wheat bulbs for the headlights and some suitable 1.5 volt micro-miniature bulbs for the ditch lights. Cut a piece of the foil board to fit the width of the hood and make it long enough to allow you to mount four diodes on it, end-to-end, with a little extra length to allow for insulating gaps. Using a pencil to mark the foil side of the board, divide it along its length into five sections: what you need to do is drill holes through which to mount the diodes, four up one side, all facing the same way (either the pointed or striped end) and four down the other side, all facing the opposite direction to the first four. Before you solder the diodes to the board, use a file or a cut-off disc in a motor tool to cut insulating gaps in the foil. There should be a gap completely across the board so that each diode's leads are separated by a gap. (Looking at the board standing on its narrow end, the bottom section, one, would have two holes in it for the one lead of the first diode in one direction and one lead of the last diode in the opposite direction. The next section, two, would have the leads on the other end of these two diodes, plus one lead from each of another bi-directional pair of diodes. The third section would have the opposite ends of this pair, plus one lead each of the next pair. The fourth section, the other ends of this pair, plus one lead each of the next pair. The fifth section is for the leads on the other end of the last diode pair. The sections at both ends require one extra hole each: solder a wire to one from the power source, and from the other to the motor. In addition, an insulating gap needs to be cut in section four to divide it along its length so that the leads from the diodes facing "up" are isolated from the leads in the diodes facing "down". For any lights that are to be directional, connect one wire to section two, the other to one side of section four. The corresponding light for the opposite direction connects to section two also and to the other side of section four. Any lights that are to be on in both directions, connect one wire to section one and the other wire to section three.
I hope I've described this adequately: if you can find the article, the diagrams are much easier to understand. And the circuit does work, although I've given up lights in exchange for more weight for added traction.
You might be able to get a copy of the article from RMC: doesn't hurt to ask.
Wayne
