RailPro > RailPro Specific Help & Discussion
Frog Juicers compatible with RailPro?
Alan:
Forgive me if this comes off as condescending. I do not mean it that way. The fuss over frog is important. It is for Joel, it was for me. I am merely boiling it down to its brass tacks.
All of the following assumes dead frog is not an option.
Powered frogs, to prevent stalling, need some method of aligning frog polarity with point movement. Juicers (incl SmartFrog) do it by short detection so there is no user interaction. Switch machines also make it automatic through micro switches, etc. Conceivably it could be done with parallel wiring/switching with turnout motor fascia switches. Or with micro switches hooked to manual ground throws, etc. Shucks, in this day and age, it is likely an Arduino or other micro processor solution exists out there. Regardless of the mechanism employed, ultimately frog polarity control without direct user intervention is the desired outcome. Am I correct Joel?
The RP issue that compounds the problem is all popular frog juicers are designed for square wave AC short detection (DCC). Passing DC through them may or may not work with probability leaning heavily towards won't work. Detectors (juicers) that rely on an inductive coil to sense current (most products) definitely won't work the same or at all. The signal being monitored will be different for DC through an inductor compared to AC through an inductor. The device has to be designed from the get-go to detect DC current rush. Hall Effect devices come to mind. The Ring AR-1 is an example of such device. It is designed to detect DC current, without the use of an inductor, and so could be used to power frogs. Although at $39.99 a pop it would be an expensive way to go.
If I understand correctly Joel is seeking a practical short detector and polarity reverser for DC operation. The SmartFrog sounds like a possible solution. My concern is the fact the SmartFrog is a mechanical relay device. We know from years past relay based devices work. But we also know they are slow in response time and as a result tend to have a lot of serious arcing going on at the wheel/frog. The old turn-out-the lights-run-trains observations. It would be beneficial to find an all electronic device with transistors that operate at near instantaneous speed i.e MOSFETs with a fast drain. Exactly what the DCC crowd enjoys with current frog juicers. Transistors if for no other reason than to reduce the wheel/frog pitting that will eventually result because of relay action.
And, as Joel rightfully is concerned about, compatibility with RP products namely power supply. What if the SmartFrog relay action is slower than the trip action time of the Ring power supply internal circuit breaker? Only way to know is to try it. And even if it works you won't know if it will work every time everywhere. Wiring length, bus impedance, supply load, and many more variables are in the equation.
The "allow the mistake to happen (short circuit) and then quickly resolve it (reverse polarity)" is, in my mind, a poor approach to the problem. No denying it is a popular approach. I just don't like it and have rambled on this forum about it in the past. I am of the opinion it is better to not allow the problem to occur in the first place. This brings us back to frog polarity controlled by points position. Either flip a toggle switch or tie it to switch motor contacts. Done.
Dean:
I understand what you are saying, but I think you summed up my position when you said, "Powered frogs, to prevent stalling, need some method of aligning frog polarity with point movement" Exactly! that's what the points do in a powered frog. The points supply the proper polarity to the frogs. In the power routing switch, the points also send power to the main or the diverging route rails from the frog. This can cause problems unless you have gaps between the main and the switch, and a gap between the diverging route and the switch.
In the DCC friendly switch the frog is insulated from the rails but gets it power from jumpers that are attached to the points. The rails leaving the frog going to the main and diverging route also get power from these jumpers except that those rails only get power when the switch is selected for that direction. All the tracks can be connected to the rails of the switch.
When I install a power routing switch, I install the switch, leave a gap at the main and diverging route rails, install a Caboose Ind ground throw and run my trains.
When I install a DCC friendly switch, I install the switch, connect all the rails to switch, Install a Caboose Ind ground throw and run my trains.
My layout has gone from DC to two different DCC brands and now to RailPro. I have not had to change any of my track work for any of these systems.
But, maybe Peco does something weird. All my switches are Shinohara or Walthers/Shinohara.
William Brillinger:
--- Quote ---This can cause problems unless you have gaps between the main and the switch, and a gap between the diverging route and the switch.
--- End quote ---
And that's my problem. I have Peco insulfrogs and they are not gaped after the frog. I'm still mulling over the best approach to adding a gap to them without pulling up track.
Alan:
Frogs are not electrically connected to point rails or at least shouldn't be. Point rails do not change polarity. If they did, and there is no reason for them to do so, there would be a serious risk of a point rail shorting to the flange side of a wheel. All of my point rails are hard wired with feeders to their respective rails. I too exclusively use Walthers Shinohara track. The points are fastened to the throw bar with a rivet that has a hole in the middle. I solder feeders inside of those rivets. They do not change polarity. My frogs are polarity switched via Tortoise switch contacts.
The only way a short occurs is if the engineer runs the switch. Then the local block circuit breaker trips before damage is done. Eventually I will have protection from this possible event using IR sensing on the turnout legs to automatically change the frog polarity. The engineer will still run the switch but there will be no short induced arcing in the process.
A power routing switch (Peco I believe) is a unique bird. In order to have frog polarity changing capability then both point rails have to be electrically bonded together with both electrically connected to the frog. Power is then transferred from whichever stock rail is currently in contact with the point rails. This makes the frog automatic but raises all sorts of other issues including the aforementioned wheel flange shorting. An even bigger problem is reliance on point rail to stock rail for electrical conductivity. A little bit of oxidation and the connection becomes unreliable especially at high current load. Walthers Shinohara 88xx series turnouts do not have electrically bonded point rails thus have no inherit means of changing frog polarity. Walthers frogs are electrically isolated from all other parts of the turnout.
In this image you can see the feeders from the point rails coming out beside the Tortoise actuating wire. They are soldered directly to the track bus. You can follow the white wire in the image. If Walthers Shinohara point rails were electrically bonded then this arrangement would short out as soon as power is applied. Obviously it doesn't thus proving the point rails are electrically isolated from each other.
Dean:
--- Quote from: William Brillinger on July 12, 2016, 08:10:07 PM ---
--- Quote ---This can cause problems unless you have gaps between the main and the switch, and a gap between the diverging route and the switch.
--- End quote ---
And that's my problem. I have Peco insulfrogs and they are not gaped after the frog. I'm still mulling over the best approach to adding a gap to them without pulling up track.
--- End quote ---
Put the gap between the switch and the layout rails. The rails that need gaped are the ones that come from the frog. Maybe you can slide the track connectors.
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