AC power for locos

[mogul264]

Not to throw more junk in the game, but has anyone ever considered AC to power tracks? We could have DCC direction/speed control and full-wave bridge diodes onboard to rectify power to DC (or use AC motors?)  for loco motors. Could this eliminate need for loops needing switch reversers, etc, and simplify track wiring?

AC would be continually supplied to all tracks, on-board transformers reducing to lower required voltages,  rectifiers changing it to DC for power, DCC circuitry, etc, in the locos. Obviously, this would require loco mods -- wheel to axle insulation, etc, since there would be continual AC on the tracks. Placing an engine on the track wouldn't cause it to move until DCC commands were sent, these controlling direction and traction effort. Higher AC voltages, say 25 or 30v, could be supplied for more power, with transformers stepping down to required potentials.And, these shouldn't add much weight, with today's circuitry. Incandescent lamps don't really care whether they have AC or DC, although LEDs do. Again, use rectifiers for these. And, relays and some motors (universal types) also can use either, as well.

Just a thought.  I'll sit back and listen.

[tomikawaTT]

Lionel, Marklin and other manufacturers have used AC track power for a century or so, so the idea isn't exactly new.  Present-day DCC effectively puts AC on the track - just not the pure sine wave of ordinary AC house current.

That said, you would still need to handle reverse sections as they are handled now.  Note that the "pure" AC players feed three rail track.  So did early day DC, until the problem of insulating wheels from axles was solved - about the same time that I was being born.  AC "Phase" is just as critical as DC "Polarity."  Bridging a single gap in 2-rail powered track after changing physical direction by running around a reverse loop would still cause a dead short.

Adding a bunch of extra electrical plumbing to the inside of the locomotive to avoid putting a simple rectifier in the power supply is a gross violation of the KISS principle.  I don't think we really want to go there.

Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL system)

[rrinker]

 You've just described DCC, only with sine wave AC instead of square wave. The only way to elminate special wiring for reverse loops is to use a third rail. Or run everything with onboard battery power so you could leave the track in the reverse loop unpowered, sontrol would have to be RF since the reverse loop would still short out a track-based control signal.

 The difference with DCC is that the phase of the carrier signal has no bearing on the actual direction of travel of the loco, this you can correct the reverse loop short by changing the phase under the loco, rather than changing polarity on the main liek you do with DC.

                               --Randy

 

[Texas Zepher]

mogul264

Not to throw more junk in the game, but has anyone ever considered AC to power tracks? We could have DCC direction/speed control and full-wave bridge diodes onboard to rectify power to DC (or use AC motors?)  for loco motors. Could this eliminate need for loops needing switch reversers, etc, and simplify track wiring?

Hate to burst the bubble, but the need for reversing loop switches has nothing to do with DC, AC, or DCC.   The issue is two rails vs the center 3rd rail that Lionel and Marklin use.   If one only has two rails there is going to be a short circuit in a reversing loop, wye, or turntable regardless of the type of power put to the track.