Am I correct to understand that Tortiose switch machines can handle up to 12 volts and 4 amps through its auxiliary contacts which could be used to provide power tot the frog ? However, most DCC systems provide greater current, such as 5 amps. If so, how can one best (cheap and easy) make the Tortoises compatible with such DCC systems?
it is not cheep.
I think you want devices called “Hares” which are boards designed for torquistes. (Spelling?)
I dont know much about those machines yet but am researching.
It’s usually not a big problem as the chances of pulling full amperage through the frog is pretty remote, especially if you keep the frog as small as possible.
Paul A. Cutler III
Weather Or No Go New Haven
Mark;
Use a 50W automotive tail light bulb in series with the powered frog, the bulb will provide current limiting during a short circuit and provide a visual indication when there is a short.
a DCC booster might provide 5 amps of current but your loco doesn’t draw anywhere near that . the switch contacts only need to handle what your loco will draw . since most modern locos are rated at less than 1 amp even when stalled , the 4 amp rating will easily be enough to handle a 4 engine consist .
Just to confirm as others have said . . . not a problem. I have about 100 Tortoises, nearly all using the relays to power a frog. Nary a problem. I run multi-unit diesels with sound, steam with sound, lighted passenger cars, etc.
As an aside, I suspect that rating is way low. I bought some used Tortoises, one of which didn’t work, so I took it apart just to see how it works. The relays are mechanical, not electric, so I’d bet they’d take many amps for quite a while, instead of the one or two they’d get for a few seconds running even high-current locos.
A train using 0.5 amps will only draw 0.5 from a 5 amp supply - for that matter, a 50 amp supply.
Todays BETTER engines run at half that. No problem.
That’s true for normal running. However, a short at the frog could put the booster’s full output on the tortoise’s contacts. And running a loco into the frog end of a turnout that’s thrown against it is an easy (and fairly common) way to create just that kind of a short.
In my opinion, some form of overload protection, either the bulb method that nfmisso mentioned or a power manager (I use PM42’s) is cheap insurance.
Maybe not cheaper than changing out an occasional tortoise with fried contacts, but certainly cheaper than replacing that custom-painted loco that now has a heat-warped shell and welded trucks!
Steve
But also the carrying capacity of the contacts is greater than the switching capacity - this is generally true of any type of switch. At one point there was a message from Cirtuitron posted to the effect of “don’t worry about it”.
And in HO and N scales at least, you probably shouldn’t have a full 5 amps goign to any particular portion of the layout, instead break it down into power districts with circuit breakers and limit the potential current to any given section.
–Randy
Save the ‘tail light bulbs’ and other overload protection for the power districts, blocks, etc.
The Tortise will handle the frogs without any problems on their own. The switching limits of most switching divices are rated for the time of the actual switching process.
As you would not be switching while and engine is on the frog, there is no problem as there would be no electrical load on the switch.
Thanks for the advice.
Randy, you’re right about power districts. That’s actually what I meant, although after re-reading my post I sure didn’t make it obvious. It wouldn’t be very cheap insurance if you protected every frog with a PM42 section!
But speaking of power districts, I power my stationary decoders from their own, which is separate from any track districts. So theoretically, I could throw a shorted Tortoise and get that track district’s full amperage across it’s contacts during make and break.
Steve