gregcare you sure it isn't a 2-pole rotary switch?
I think you meant 2-position rotary switch.
Thr circuit you posted redirects both + and - to the track, hence the 'two rotary switches on a common axis'...
CharlieMI wish there was a edit capability on this forum.
there is. select the blue edit button
isi the above circuit similar to what is described in the article?
ROBERT BRABANDthe article calls for a 1-pole 12-position rotary switch.
are you sure it isn't a 2-pole rotary switch?
you can use a pair of 12DC wall adapters instead of a center tap transformer
greg - Philadelphia & Reading / Reading
Obviously my brain outruns my fingers when typing. I hope you can wade through the typos and get the jist of my comments. I wish there was a edit capability on this forum.
I di not have access to the 2000 MR issue you mentioned so I can't comment directly, but it sounds like it requires a dual polarity power supply. That would be the reason for a center tapped transformer. The dual polarity supply (=/- 12 VDC) is nice in some respects but not at all necessary for Tortoise operation. On big layouts it can save some toggle switch cost (single pole vs double pole) but today the savings are minimal. I can refer you to the May 2009 issue of MR in which Oliver Tansey describes a route control system for Tortoises that works very well. It only requires a single polarity 12V supply and a single pole rotary switch with the number of positions equal to the number of routes you plan. I am using this approach several places on my layout and it works very well. The only drawback to it is a bit more complicated wiring under the table and the addition of 2 resistors per Tortoise. There is also a slight delay when waiting for several switch motors to move is sequence but it's by no means objectionable. A lot faster than the prototype with one or two switchmen .
For the rotary switch I suggest looking at Digikey. They sell several versions by Grayhill. You can get the with adjustable numbers of positions so you expand or contract as your layout changes. Price is around $20 for a single pole 2-12 position switch. If you add asecond deck (pole) you can easily implement an LED route indication for the control panel.
As for transformer rating, each Tortoise will draw a little more than 20 milliamps at 12V so 16 would slightly exceed yor 300Ma transformer. However that's for 12V. 12V 1 Amp transformers should be redily available but many folks use "wall worts" which are really easy to find.
Jerry Leone in his "Back on Track" video series makes reference to a system detailed in the November 2000 Model Railroader for Route Control for Tortoise turnout motors. Radio Shack does not seem to have the center-tap transformer referenced in the article, and a search brings up about 22,342 options which is mostly confusing to the "non-electrician me." Isn't the Internet a wondrous option?
I did find one however that may be what I need, though it's only 6v DC output 300 mA.
https://www.amazon.com/Philmore-Power-Supply-Transformer-Center/dp/B00OGLBQQQ/ref=sr_1_4?dchild=1&keywords=center+tap+transformer&qid=1632586864&sr=8-4
If I've heard and understood things correctly Tortoise machines will operate on 6 volts, slower than with 12 volts but many think of that as an advantage. And 300 mA should power a lot of machines - for my application I'll have eight double-ended staging tracks, so 16 Tortoise. Is this the transformer I need? Or can someone point me in the direction of one that does meet my needs?
And because I came here before I adequately did my research, the article calls for a 1-pole 12-position rotary switch. Best options for that perhaps?
Thanks for your guidance. Robert