I read somewhere that you can use a relay and a diode or two instead of an auto-reverser for controlling track polarity through a wye with Tortoise switch machines. If this is true, can someone provide a circuit diagram?
Thanks in advance,
John
You may need a relay as well. There is a diagram and explanation on Allan Gartner's web site that will help. The WYE discussion precedes the one for the Tortoise.
Alan
Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/
The Tortoise motor has a full set of DPDT contacts that can be utilized - the 'catch' is that they only have about a 1 amp rating. As 'Doc' mentioned, you can use an external relay with heavy duty contacts as shown in the link 'Doc' provided.
That said, I did wire a wye just using the Tortoise contacts. All I did was 'turn' engines(15" tail track), and they were stopped when I threw the turnout. I never burned out the contacts, but replaced that 'Wye' with a nice Walthers 90' TT a few years ago!
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
If it's a turning wye especially, there can only be 1 or maybe an MU set of diesel locos on the tail track at a time, and they will be stopped when the contacts move - a loco with decoder with the motor not running but maybe the lights on only draws a few ma, so the Tortoise contacts should be plenty robust to handle things. At least if we're talking HO or smaller here.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I use the tortoise contacts on my Oscale layout that routinely pulls 5 amps. They work great as long as you are not throwing the switch beneath a loco. Even then they might work fine but I have never done it. (from what i have heard) the 1 amp rating only refers to the amount of current that can pass through while the turnout is being switched. Since we typically throw the switch long before the train gets to the frog, this is not an issue.
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Thank for the responses. I reviewed Allan Gartner's link but don't see any diagram using the Tortoise internal switches. The tail of my wye goes to a stub yard, which, in the future, I might reconnect to the layout. My understanding is that that will likely require a "real" auto-reverser.
Since I do not want the stub yard to shut down while switching, can I still use the relay and diode? If I elect to use the internal switches on the Tortoise, how do I wire this?
I would be concerned with the "switching time" using a mechanical device like a Tortoise. A solid-state auto-reverser, like the Tony's Trains ones, will only take milliseconds to flip over. The trains don't even notice this. A mechanical switch, on the other hand, is probably going to take hundreds of milliseconds, which may not sound like a lot, but it's enough to shut down some decoders and cause them to cycle back up again. A relay is somewhere in between.
If you have a sound engine, you'll notice the shutdown. If your engine is moving, it will stop, and then slowly come back up to speed, particularly slowly if you have a lot of momemtum programmed in.
As was mentioned, this doesn't matter as much if the engine is already stopped, as it would be on a turning wye, but if you're feeding an operating yard it might be undesireable.
Does anyone know what the electrical switching time of a Tortoise is like?
It takes an iron man to play with a toy iron horse.
a tortoise switch time is dependent on the voltage used, but even at the quick end it is way too slow to use the contacts for flipping/switching power and expecting a sound engine not to notice. best method would use an ARM to deal with polarity issues of the loop or wye track, and just use the torty for moving blades and switching only frog polarity, though on a loop the frog is always the same as the loops inner rail so no irj's are needed on the inner loop and the frog could be back fed from the loop if the electrical timing is correct or the point is 'dcc friendly' electrically so that blade possition ( in contact with a stock rail ) has no effect on frog polarity.
I agree that an auto-reverser is the way to go. The incremental cost increase over a diode and relay will likely be worth it and if I decide to connect the other end of the stub yard back to the layout, I'll be covered.
Thank you all.