Is it possible to adapt the Atlas N scale # 2790 turntable to DCC?
I have an HO scale turntable. Mine is just a simple DC motor that uses a Geneva drive to stop at each stall. It should be a simple job. I run mine from a control panel with a DPDT toggle from an old DC power pack.
It takes an iron man to play with a toy iron horse.
After some additional research, I think that I could hook the turntable motor to a Digitrax DH126 decoder. I would set the decoder address to 00. Connect the track wires as drops from the track and connect the motor wires to the turntable motor wires using forward a reverse to turn the turntable. Would this work?
Caldreamer
I think a DH126 would be fine, but pick another address. On my Lenz system, the 00 address is reserved for DC locomotive operation.
MisterBeasley:
Since I will only be using the forward and reverse features of the decoder to control the direction of the turntable, I do not think that it will really matter if the decoder is set to 00.
Are you using a Digitrax DCC system? Allowing an engine or in this case your turntable motor to stand for an extended period on address 00 can do damage to the motor. Using a real address would be better.
Joe
caldreamer MisterBeasley: Since I will only be using the forward and reverse features of the decoder to control the direction of the turntable, I do not think that it will really matter if the decoder is set to 00. Caldreamer
It will depend on which DCC system you have. On my system, running DC as Engine Zero will not address any decoder. It uses a thing called "stretching the zero bit" to provide an unbalanced DC voltage on the track, emulating a DC power pack.
It may work fine on your system, depending on how it uses the 00 address.
I have an additional complication which probably doesn't apply to you, but the turntable is within an auto-reverser section which flips the polarity of the track.
I found my TCS M! decoder. Just spoke to the tech at TCS and he said that as long as I use the long address of 0000 my idea will work. Just have to watch the voltage to the motor. Since I will be running it very slowly that will be no problem. Thank you for your input.
In DCC, primary("short" or "2-digit") address '0' is the broadcast address. The reason some DCC systems use it for analog engine control is because you cannot use it for a decoder. You can program a decoder to primary address 0, but ALL decoders are supposed to respond to that address, so you would not be able to control that one seperately. Extended("long" or "4-digit") address '0' is a regular, seperately controllable, extended address, as long as your DCC system supports it (many DCC systems do not support an extended address below either 100 or 128, depending on the system).
Seems to me that DCC control of a turntable is over the top and a very complicated and expensive way to operate it when a $2.00 DPDT center off switch will suffice. The turntable isn't a train. It doesn't move and need walk around control. I assume that the operator regardless of control method would need visual confirmation of alignment and therefore be where he could watch the operation close up. Just my two cents
caldreamerJust have to watch the voltage to the motor.
How much in the way of amps does a this turntable motor draw? I don't know enough to hazard a guess, but just like an older loco converted to DCC, there is a limit on what the decoder can handle.
Henry
COB Potomac & Northern
Shenandoah Valley
Maximum draw is .5 amps the same as the motor. Since it will be moving very slowly I would not come any where near the .5 amp maximum.
Is there any reason at all to use 00 as the address? 1000 would have no complications, and neither would 4567.
If the model number is 2790, how about that?
MisterBeasley Is there any reason at all to use 00 as the address? 1000 would have no complications, and neither would 4567. If the model number is 2790, how about that?
Well, if he uses extended address '0' and his DCC system supports it, there shouldn't be any complications.
According to the tech at TCS as long as I use the along address of 0000 it will work without any problem. My concern is that the Atlas N scale turntable does not have a table jut a piece of something with track running through it not a pit. I am wondering if it is deep enough for me to make a custom table to fit into a pit. Does anyone know how deep the turntable is?
Again, I'm in HO scale, but I did exactly that with the Atlas turntable. I mounted the turntable below the surface and built a pit wall around it. I them built a thin styrene cover over the turntable deck so its rotation could not be seen. I built the turntable bridge above that, so it rotated with recessed, covered deck and was supported with bogies and a pit rail.
caldreamerDoes anyone know how deep the turntable is?
I think you'd want to use the special 2791 motor made for this table; it screws in place of the hand crank and according to the directions just uses normal two-wire DC with polarity reversal. I expect that at the 'low voltage' you plan to be using, the dead time the table is aligned with each position should be relatively long.
Here is a link to the surprisingly difficult-to-find instruction sheet for 2790 and 2791:
http://download.atlasrr.com/pdf/N%20Turntable.pdf
As noted, perhaps the logical thing is to conceal the entire flat structure including the rotating disk under the bottom of a 'pit' with a large enough hole in the middle to allow a sufficiently stout center post and with ring rail to support the ends of a bridge. It's likely going to require careful modeling to get the tracks on such a bridge in sync with what the 'hidden' disc and rails (and locking mechanism) are doing, but as noted it's been found possible.
I was going to use the 2791 motor, just control the direction with my hand held controller. It may not be worth the effort of building a bridge unless a member is willing to share pland for a bridge for this turntable. The only other turntable avao;able is the Walthers which is grossly overpriced.
I think most of the reason the Atlas design can be had so 'cheap' is the flat-plate design, with the contacts immediately underneath and the indexing at the edge of a continuous disc rim. If it had 'depth' and a separate bridge it would start to cost more.
You might be able to cut away the portions of the disc surface not occupied by the 'track' and lower the depth of the pan between the center pivot and the retained rim. You would then detail the underside of the resulting 'bridge', lengthening the contacts to the now-dropped slip rings, add structural members above, etc. and live with the moving 'rim'.
There is something of a dusadvantage to run this from DCC when there is no way other than 'eyeballing' the turntable to determine when it is engaged and then locked to a particular track. As I understand the mechanism, it locks for a turn of the crank at each approach position whether a track is installed there or not, and there is no way to get it to 'ignore' empty tracks but still rotate the bridge. So it might take a very long time to rotate around, say, 180 or more degrees,and all this time you're looking at your DCC controller set to 0000 so as not to overshoot or miss the turntable position instead of using the controller to run trains...
There are ways to get this to indicate the 'currently selected track' and to build a programmable controller that would step the table unattended to a particular position, but unless you love hobby electronics that's a big, complicated, and possibly expensive undertaking. (And I suspect the action might still be comparatively slow)