The dynamo on 483 put out a nominal 24VDC when the late C. M. "Bud" Edmonds and I recorded some of the first train movements over the C&TS trackage in the fall of 1970. We had a tough time charging the battery box for our 1/2" Ampex AG-440-4 4-channel machine as the voltage would vary a great deal with any change in steam pressure to the dynamo. We took a power feed from a connector on the rear of 483's tender. I would suspect that the San Juan cars were powered in the same manner. Any idea what sort of voltage regulator the Rio Grande used to keep the lighting constant? -- Ed