I'm working my way through Andy Sperandeo's book, Easy Model Railroad Wiring. His diagram on page 31 solves my eternal problem with power-routing turnouts. He wires around them so that the points don't HAVE to make good electrical contact to route power. I'm sure you're all familiar with this apparently very common procedure, and it looks great to me. A SPDT switch routes power from both north and south rails (beyond the points at one end of the turnout) to one of the frog rails at the other end of the turnout. But I'm very confused. How can this possibly work if you're not supposed to "feed the frogs"? The contact on the frog rail looks like it will feed the frog. I'm pretty thick when it comes to electrical diagrams and I can't help feeling like I'm missing something really important. Can anyone point to what I am missing?
The SPDT switch you refer to is actually a contact attached to the switch machine or turnout throw linkage. The contact changes position when the turnout is thrown to ensure the frog is at the correct polarity.
"Not feeding the frog" refers to track feeders that do not change polarity when the turnout is thrown. The frog should be isolated so that only the correct polarity is reaching it through the SPDT contact.
I hop this make sense for you.
Fred W
Okay, umm...I'm not sure I do understand. Gee, I feel dumb. So if two frogs are facing each other I should still cut the gaps to isolate the frogs from each other and run feeder wires to the track between them as usual. Is that what you're saying? And then for each turnout, run the wires from the points end, through the switch, and finally to the frog rail just as the diagram seems to show. In other words, Fred, I wasn't missing anything, I just didn't understand how it all worked? Is that what you mean?
chaya wrote: Okay, umm...I'm not sure I do understand. Gee, I feel dumb. So if two frogs are facing each other I should still cut the gaps to isolate the frogs from each other and run feeder wires to the track between them as usual. Is that what you're saying? And then for each turnout, run the wires from the points end, through the switch, and finally to the frog rail just as the diagram seems to show. In other words, Fred, I wasn't missing anything, I just didn't understand how it all worked? Is that what you mean?
By George, you've got it!
The frog should ONLY receive power from the contacts on the switch actuator (which may be a machine or a hand-thrown device with contacts. One I just installed is a toggle switch, mechanically connected to the throw bar.) Frogs back to back must be isolated from each other. If the space between the frogs is long enough (think passing siding,) that rail should be isolated at both ends and have its very own feeder. In analog DC it would be wired as a separate block.
Chuck (modeling Central Japan in September, 1964)
tomikawaTT wrote: The frog should ONLY receive power from the contacts on the switch actuator (which may be a machine or a hand-thrown device with contacts. One I just installed is a toggle switch, mechanically connected to the throw bar.) Chuck (modeling Central Japan in September, 1964)
The frog should ONLY receive power from the contacts on the switch actuator (which may be a machine or a hand-thrown device with contacts. One I just installed is a toggle switch, mechanically connected to the throw bar.)
Thanks Chuck! This brings me to another issue about turnouts. I would really, really prefer to have mechanical linkages for mine that lead to knobs on the fascia. Does anyone here have any favorite ways to do it and perhaps even articles or books where they found them? I have two articles showing mechanical linkages but I'm not totally satisfied with either. (The linkage would have to incorporate a switch, of course, since I prefer power-routing turnouts).
There seem to be as nearly as many different methods of doing mechanical linkages for turnout throws as there are model railroaders. They break down into several different categories, though.
For contacts on home-made linkage, slide switches or toggle switches are usually used. The switches also provide some latching to hold the points over to one side or the other. The switches can be installed almost anywere in the linkage chain. Usually switches are mounted just behind the control panel or under the turnout for wiring ease.
An alternative to a switch is build your own contacts using a metal disk or arm, and screw heads or nails.
Flexible push-pull cables are quite common. These range from bicycle brake cables to automobile choke cables. Humpyard levers (a commercial lever throw and linkage) also use these.
Rod and bell crank (if necessary) are another alternative. The fanciest ones are the ones used on model aircraft to run control surfaces. The bell cranks are used to turn the direction of the force and increase/decrease the throw. I've heard of coat hanger wire being used for the rod at the cheap end.
The last category uses a non-rigid string, fishing line, flexible wire, or similar with a spring or weights to pull the linkage in the reverse direction. These are more difficult to use with a slide or toggle switch (but it can be done), but work well with a home-made or commercial SPDT electric contact.
At the control panel or fascia throw end, I've heard of everything from barrel bolt slides to drawer pulls and knobs to miniature interlocking levers.
Have some fun designing your own, and let us know what worked for you.
For manual operation, you might want to consider these:
http://www.humpyard.com/
Thanks so much, Fred and Pondini. Great ideas. I'll let you know what I come up with!