AC->Full Diode Bridge (4 diodes)->DPDT switch (6 terminals) The top two terminals should be wired criss cross to the bottom two. The middle two go to pins 1 and 8 on the tortoise.
Diodes are direction sensitive. The 4 diodes should be arranged in a square shape (one per side) Two sides should have the silver bands facing each other. The point where they are soldered go to the switch. The other two sides should have the silver bands on the diodes facing AWAY from each other. The point where they are soldered go to the other terminal on the switch. The last two points connect to the AC power.
See this article for the diodes and how to hook them up into a full rectifier.
http://www.circuitstoday.com/full-wave-bridge-rectifier
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
For the best definatibve information on the connection of a Tortoise, see the Lion.
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Forget about AC and diodes and just use a DC power supply and a DPDT toggle switch.
Rich
Alton Junction
Hi, Paul
With an AC supply one leg goes directly to terminal 1. The common of the switch goes to terminal 8 and the other leg from the transformer goes to both diodes then the cathode and anode of each diode go to each side of the SPDT.
Look at the diagram labeled "3" on page two of the Circuitron instruction sheet.
http://www.circuitron.com/index_files/INS/800-6000ins.pdf
With this setup you only get half wave DC so the AC input has to be higher. I wonder if the OP is using the AC terminals of a power pack which are ~14 VAC?
We will have to hear back from him to find out.
Regards, Ed
Shouldn't you be using a DPDT toggle instead of a SPDT? Because if you are using a SPDT, then that would explain why it only throws in one direction.
Paul A. Cutler III
Are you using a "wall wart" type transformer for your AC supply? Be sure it really is AC 14 to 16 volts. If it is DC adding the extra diodes will stop current flow.
If it is AC perform a test by placing one wire from the transformer to terminal 1 of the Tortoise. Take your two diodes and place them in opposite directions and twist the other transformer wire to one end.
Then touch the lead of each diode, one at a time, to terminal 8 on the Tortoise. It should now move left or right depending which diode you touch.
If this works, then put your switch back in line (are you sure you have your common terminal on the switch identified?) and go from there...
Ed
Check to be sure you have the diodes pointed in the right direction. One should have the stripe at the opposite end of the other stripe.
Even though you are putting in AC, the diodes are actually making half-wave DC into the Tortoise.
Study the diagram again and figure out what is causing the problem. It is possible, but unlikely, that one of the diodes are bad?
Good Luck, Ed
George In Midcoast Maine, 'bout halfway up the Rockland branch
I installed my first under the layout slow motion machine and did the wring according to the instructions provided for AC. I tried those Diods and still no response. The throw only works one way using the SPDT switching set to either position selected. Now, when i flip the connecting bar to the machine, I get the throw to change as it was meant to. Why come I can't get it to work when I throw the toggle switch to either settings?