Confused maybe?. I have 5 spur tracks running off of my turntable (2 into the engine house). The spur tracks will each be wired off of the DCC power buss of the layout. The turntable deck is also wired off the buss, and has a ring on it which rotates as the deck rotates. I know the deck track wires need a switch (on the control panel) to change the polarity of the deck track to match the polarity of the spur as a loco enters or leaves the deck. At first, I thought I needed a switch to each spur to be able to change the polarity in the spur, but the more I think about it, I'm guessing I don't.
Do I need a polarity switch in each spur?
I am planning to have an off switch to each spur, so I can turn power off in a spur sitting idle. And I'll have an LED on the panel for each spur to show if the power is on or off to a spur. The turntable will also have a push button switch on the panel to apply power to the turntable, and a switch to change its directional movement, and an LED.
Does all of this sound correct? Thanks in advance for helping.
Hal
Who made the turntable? Some of them have built-in reversing circuitry, while others to not.
The Atlas turntable does have this feature built in. To wire it properly, you have to note where on the circle each of the stub tracks and leads are. On the Atlas, each track slot is marked with an A or a B. All the A's have one polarity, and all the B's have the other.
If you don't have a turntable that handles the polarity for you, then you'll need a double-pole, double-throw toggle. It only gets wired to the turntable, not the stub tracks. This is one of those places where a DCC auto-reverser will make the whole thing work without even thinking about it. Wire it to the turntable tracks and forget it. The auto-reverser will automatically adjust to whatever stub or lead you move the engine to.
By the way, if you have a situation where the engine is actually longer than the bridge, and you get around that by running it directly across from the lead to the stall, you want to be sure that the polarity on the lead and the opposite stall tracks are the same.
It takes an iron man to play with a toy iron horse.
Mister Beasley, the turntable is a 90' Walthers (but the cheapie, and not the expensive), so there is no automatic reverse capabilities.
I think you are agreeing that I need a toggle to handle polarity on the turntable, but I do not need any polarity toggles in the spurs (stubs is a better word).
Thanks, Hal
I don't think you need it, most turntables handle it, but this autoreverser is only $30.
http://digitrax.com/prd_powerman_ar1.php
Dave
Lackawanna Route of the Phoebe Snow
The Walthers HO 90' motorized kit that I built did not reverse polarity. It comprised two copper wipers that wiped two brass rings. The rings were solid, and their wipers maintained contact throughout the rotation. There was no split ring design, so when the bridge was rotated 180 degrees, the bridge rails were the same polarity as before, but they were not oriented polarity-wise to the polarity of the stubs.
selector The Walthers HO 90' motorized kit that I built did not reverse polarity. It comprised two copper wipers that wiped two brass rings. The rings were solid, and their wipers maintained contact throughout the rotation. There was no split ring design, so when the bridge was rotated 180 degrees, the bridge rails were the same polarity as before, but they were not oriented polarity-wise to the polarity of the stubs.
as mentioned above, use a cheap auto reverser ( the type used on reverse loops ) and use the feed from that to power the rails on the deck. if a loco enters or exits from any track and the polarity is incorrect, the deck polarity gets reversed to suit. no loco is ever going to be exiting and entering at the same time. the only scenario where this method would not be wise is IF the turntable can be set to run a full train through it as part of a running line or yard ( some people do it ) if your trucks have metal tyres the auto reverser could become confused or fried if a wheel set was bridgeing both ends of the deck at the same time!!! this is the easiest method without an auto reversing mechanism built into the turn table.
A DPDT on/off/on switch on the bridge track should work fine. That's how I'm going to wire mine.
Thanks everyone for the help. The automatic reverser link by Phoebe Vet looks good and Locoworks describes using it well. Selector, my turntable is like you described with the rotating collar.
For now, I'll probably us a toggle for polarity on the turntable (Lother and others)..... and go to the automatic reverser when I get into my first reversing loop in the layout.
donhalshanks Thanks everyone for the help. The automatic reverser link by Phoebe Vet looks good and Locoworks describes using it well. Selector, my turntable is like you described with the rotating collar. For now, I'll probably us a toggle for polarity on the turntable (Lother and others)..... and go to the automatic reverser when I get into my first reversing loop in the layout. Hal
your reversing loop and turntable will need seperate auto reversers unless you NEVER plan on something entering or exiting the loop or turntable at the same time!! the snag with the DPDT switch is remembering which way the deck is and which way it needs to be set depending on what road you are using?? as your deck power doesn't get reversed you'd need to remember if the deck had spun 180 or was the same way every time you use it? fit an auto reverser straight off and have no worries, if you get the DPDT switch wrong you short out the whole layout..