[SPROGman]

QUOTE (ahammond @ 21 Jan 2008, 08:06) <{POST_SNAPBACK}>I am in the middle of converting and motorising a Peco N gauge turntable to DCC operation. I am using the standard motorising kit and driving it as a normal locomotive from the controller with a cheap TCS decoder hooked up to the drive motor and the address twenty two. The track on the turntable is fed from a DPDT switch, with centre off, to enable manual reversing of the current flow as the turntable completes a one eighty degree turn. The main problem that I am having with the conversion at the moment is the shaft on the drive gearbox slipping when under load. I am hoping to investigate and rectify that this week when I have more time.
The Peco N gauge terminal reverses the polarity automatically as it rotates. There's no need for a manual switch. Just make sure the breaks in the commutator ring are well out of alignment with the entry/exit tracks so that the reversal takes place at the correct point.

Andrew

 

[SPROGman]

QUOTE (ahammond @ 21 Jan 2008, 12:43) <{POST_SNAPBACK}>I am not that well versed as far as electrics go and stand to be corrected. But whilst I would agree with you as far as DC current is concerned I am quite certain that for AC operation with DCC then the polarity to the turntable tracks has to switched if it is rotated 180 degrees. Otherwise you would end up with a positive feed rail on the table facing a negative feed rail on the track that you are lining up with.
It makes no difference whether you use AC (DCC) or DC. The two sprung plungers pickups on the deck pick up power from the two halves of the split ring in the well. Each 180 degrees the polarity of the deck is changed as each pickup moves from making contact with one half of the ring to the other. Think of it as a rotary double pole changeover switch.

The disadvantage of this arrangement is that there will be a momentary loss of power to the deck as it turns, which may upset sound decoders.

Andrew