Am I asking for trouble if I use DC Power for some post war accessories. I am certain I can power lights with DC, but not certain about the activation motors. I tested a couple with 12v dc and it seems ok. Thanks for any information.
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I'll bet the list for accessories that CAN operate on DC is longer than the list that can't use DC. Obviously the vibra-motor mechanisms (cattle platforms, rotating searchlights, wig-wags) need the alternating voltage. I think there's a crane that requires AC voltage though not because the underlying electro-mechanism requires AC but because it uses one polarity to make the motor go one way, the other polarity to make it go the other way.
I think of all the 12V DC mechanisms in the automotive world - power locks, windows, seats, mirrors, you name it. They go up, down, rotate CW, CCW, fast, slow, momentary operation, continuous operation, etc. All the types of motions that train accessories use.
If done today, I'd think the vibra-motor type accessories would use a DC motor with an eccentric/unbalanced weight on the shaft like vibrators first felt in pagers, then cellphones and now smartphones.
Footnotes
(1) there was a recent thread about DC vs. AC where someone's grandkid said he'd rather have the gateman solenoid operate on AC than DC. Why? Because the AC buzzing made it sound like the gateman was talking! Ahh, to have a child's imagination!
(2) there have been occasional threads suggesting some vibra-motor accessories operate better using pulsed DC (using a 10 cent diode) to drive only "positive" polarity power. As to whether pulsed-DC is not "real" DC or is still AC is open to interpretation. It's interesting that recent command-control engines from both of the big O gauge manufacturers can operate on DC. While perhaps a theoretical exercise, it is now practical to have a DC-only O-gauge layout...both trains and accessories. For the vibra-motor accessories, low-cost eBay modules can generate pulsed DC from a 12V DC supply.
I think it is a little more complicated than indicated above. The current through a DC coil is determined by the resistance of the coil wire. On an AC coil the current is determined by the impedance of the coil. A coil designed to run on AC will generally run hotter on DC, maybe to the point of damaging the coil or the accessory. There is probably no problem with coils that are used interminently, but coils that are operated for extended periods would needed to be monitored. Another issue is with DC coils is that steel parts may become maginitized. This may result in operations that are to return to rest by gravity or light springs may not return. I think each case would need to be carefully considered.
When it's set up, I like to run my 182 stationary crane on D.C. because it is so much quieter.
I never noticed coils overheating. I guess the coil might run hotter on DC than AC at any given voltage, but generally, the voltage can be set lower when using DC. Maybe that balances out the extra heat.
Never had a problem with the solenoids becoming magnetized and sticking. The electromagnet would become magnetized. I addressed this by putting a bypass switch in the power supply. When the electromagnet became magnetized, I would run the accessory on AC for a minute or so to demagnetized it.
As Stan mentioned, some vibrator accessories run better on 1/2 wave DC. In fact, the 362 Barrel Loader had a rectifier built in.
In my experience, on some accessories the direction of "rotation" changed when I tried 1/2 wave DC.
Trivia question. Two Lionel postwar accessories used DC power in part of it's operation, know which ones?
465 & 375 used batteries, as well as the 3470(rolling stock, not technically an accessory).
Lionel also made Battery operated whistle controls in the 1960's.
C W Burfle posted:...
Never had a problem with the solenoids becoming magnetized and sticking. The electromagnet would become magnetized. I addressed this by putting a bypass switch in the power supply. When the electromagnet became magnetized, I would run the accessory on AC for a minute or so to demagnetized it.
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Is the switch labeled "Degauss"? 
And do you taper the AC down to 0V? 
Is the switch labeled "Degauss"? And do you taper the AC down to 0V?
It's not a tape head. A few moments of straight AC works fine.
When one operates the accessory on AC, the power is switched on and off to the magnet (and coils). There is no tapering off of the AC.
Rob got it, wasn't much of a challenge.
It wasn't much of a challenge, true, but I had to look up the catalog number of the turntable.
