- Main article: Turnout
Part of a series on turnouts (track switches) and Digital Command Control
Digital Command Control: Turnouts - PECO Electrofrog
- 1 PECO Turnouts
- 2 Shorting In the Electrofrog
- 3 Making the Electrofrog DCC Friendly
- 4 Peco Electrofrog - Modifications for DCC
- 5 See Also
- 6 External Links
PECO manufactures a number of turnouts in various scales.
They have several types of turnouts:
- The Electrofrog, subject of this article
- Unifrog, a new product which is intended to replace the Insulfrog and Electrofrog products. These products will be gradually phased out and replaced by the Unifrog line.
Differences between PECO's Electrofrog and Insulfrog Turnouts
The electrical power routing of the Peco Electrofrog is different than that of the PECO Insulfrog.
The Electrofrog is a well designed turnout. With the exception of the guard rails, there is no plastic for wheels to run on. The positive locking action of the switch points makes it the ideal turnout for anyone's layout. The main feature is an all metal frog. The Insulfrog may have an all plastic (non-conducting) frog, or a metal one with gaps.
- Be aware of the images used to illustrate PECO switches. In many ads the pictures are of Electrofrog types, despite the ad copy saying differently.
With DCC operation, there are a couple of problems. The solutions, however, are simple.
How to Spot the Differences between Electro and Insulfrog Turnouts
- Frog may be cast entirely in plastic;
- Closure and wing rails are solid;
- Plastic filled gap where closure rails meet the frog;
- Beginning of frog itself is plastic;
- Switch rails are electrically connected;
- Power Routing: Closure rails are electrically connected to the appropriate point rails.
- Closure rails are gapped before the frog.
- Jumper wires underneath bridge those gaps
- Frog, closure rails and switch assembly are electrically a unit.
- Closure rails are not electrically connected as a pair.
Power-Routing In An Unmodified Peco Electrofrog
The Peco Electrofrog switch was designed in the days of analog operation with the ability to power sidings depending on which way the switch rails were aligned. Drive a locomotive into the siding and then set the turnout for the mainline route. We could rest assured that the locomotive wouldn't creep away on us - assuming there were no additional track power feeds to the siding. The turnout would function as an electrical switch in addition to its duty as a track switch.
We could then flick the switch rails on another turnout which held another locomotive on that siding, then operate that new locomotive. This ability had everything to do with how the Electrofrog was wired - By a combination of the rails and wire bonds on the underside, the switch rails acted as an electrical switch that routed power to either the mainline or diverging route.
While it was not obvious, if the switch was set for the mainline route, a whole lot more than just the mainline route was electrified. In the bottom half of the photo below, we've traced the electrical polarity in blue and red. Take a look at the red rails. Hard to believe that all of these rails, particularly the switch and both point rails are also powered when the switch is set for the mainline route!
Digital Command Control eliminated the requirement for power-routing switches. Locomotives only moved when told to move (via the throttle). When parked, they stayed parked, even though there was still power on all the rails. We also added all kinds of track feeds because we didn't have to worry about power-routing to sidings, particularly around turnouts.
Good DCC wiring practice requires track feeds before and after a turnout. Which caused problems with the Peco Electrofrogs. Because the switch routed the power, depending on how things were wired, Electrofrogs shorted the DCC power bus.
Shorting In the Electrofrog
Making the Electrofrog DCC Friendly
- These modifications are recommended by PECO, and illustrated in their data sheet. See the links at the end of this page for links to various PECO documents.
Insulated Rail Joiners After The Frog - Mandatory
In addition to adding track feeds before the turnout and after the frog on both the mainline and diverging point rails, the first step is insulated rail joiners on the point rails (inside mainline rail and the inside diverging rail). If your turnouts are already installed, cutting gaps in the point rails after the frog and fill those gaps with epoxy or styrene, to prevent the gaps from closing later.
When you set the switch for the mainline route, the switch rails of an Electrofrog continue to power-route as before. However, because the addition of an insulated rail joiner on the point (inside diverging) rail, we no longer have a short, notwithstanding that both point rails, the straight closure rail and curved closure rail have the same red polarity.
When you set the switch for the diverging route, the switch rails of the Electrofrog continue to power-route to the diverging route. And, because we've added an insulated rail joiner to the (inside mainline) point rail, we no longer have a short, notwithstanding that both switch rails, the straight and curved closure rails have the same red polarity. As a minimum, if you are using Peco Electrofrogs, you must install insulated rail joiners on the point rails. Or gap these rails and fill the gaps with epoxy or styrene. NO EXCEPTIONS!
We still have the problem, where the wheels of our locomotives may create a short between the stock and switch rails. This is especially true for steam locomotives and 6-axle diesels. This wasn't an issue with Analog operation, but DCC is very sensitive to even the shortest time period when an issue like this occurs. One solution is to check the wheel gauge of all your motive power and rolling stock, making corrections as needed.
Taking a look at the above illustrations, the red switch rail shorts to the mainline stock (blue) rail as the locomotive goes through and its wheels span the gap between the two. OR, the blue switch rail shorts to the red stock rail as the loco goes through. If you still don't see how this happens, take a look at the graphic below. (The nomenclature in the illustrations is incorrect: Point rails are at the heel of the frog.)
As part of the process, verify the wheels and rails are in gauge with an NMRA gauge.
This is what makes a turnout incompatible with DCC.
Peco Electrofrog - Modifications for DCC
So far, you've taken care of Step 1: Adding insulated rail joiners to the point rails beyond the frog. This gets rid of the "built-in" short. We may still have an intermittent short as our locomotives go through the switch between the switch and stock rails. To get rid of this short, we're going to disable some of the circuitry (NOT the rails) and make modifications to the wiring.
This will be done in 3 extra steps and will all be done on the underside of the Peco Electrofrog.
- Cut the wire bonds between the frog and the point rails. This disconnects all power to the frog. Depending on which way the turnout is thrown, it also cuts power to one of the point rails.
- Solder some wire bonds between the stock and its related point rail. This restores power (with the correct phase relationships) to the point rails.
- Add a Tam Valley Frog Juicer (or a switch) to power the frog. This restores power to the frog and sets up a control mechanism which gives the correct polarity to the frog as a train goes through the turnout.
Let's take a look at the underside of the Peco Insufrog.
Cutting The Wire Bonds on the Peco Electrofrog
The first thing you will notice on the underside are a pair of wires to the point rails. These wires bond the frog with either "blue" electricity or "red" electricity, depending on which way the switch is thrown. This means the points are not DCC Friendly as they are both energized through the frog to closure rails, depending on the position of the switch. This makes it possible for a metal wheel to bridge between the switch rail and the adjacent stock rail through the tread and backside of the wheel.
Cut the wire bonds so that the frog is no longer powered by the switch and closure rails. If your Electrofrog turnout is already installed, you can cut the wire bonds from the top with an Atlas snapsaw inserted into the gaps in the closure rails. This is a simple matter of snipping the wires with a pair of cutters and then twisting the wires off of the rail. They should come off very easily. You now have a "dead" frog.
Solder Wire Bonds Onto The Closure and Stock Rails
- Strip about 2" of insulation off a track feed wire
- Flux and tin the track feed wire
- Flux and tin the undersides of the rails shown in the photo below
- Solder the tinned track feed wire between the closure and stock rails
- Cut the excess wire off.
- Repeat for the other pair of rails
Correct Phasing for the Frog
Looking at the underside of a Peco Electrofrog, notice a short piece of wire embedded in a groove in the plastic ties near the frog. Pry the end of this wire up. Following the route of this wire, you find that it is connected to the four frog rails. Use this wire to power the frog with either "red" or "blue" power, depending on which way the switch is thrown. This can be done with a Tam Valley Frog Juicer, the auxiliary contacts on a switch machine (such as a Tortoise or a Tam Valley servo motor) or an SPDT switch that is connected to the throw bar of the turnout. In our case, we're going to use the Frog Juicer.
As we will install the Frog Juicer under the table, we will first solder a single-wire track feed, the "frog feed". Only one "frog feed" required as the point rails will be the return on this circuit.
- Strip about 1/2" of insulation off one end of a 12"-18" piece of track feed wire.
- Wrap the feed wire around the wire from the Electrofrog close to the base of the turnout.
- Add flux and solder the wires. (Cut the excess wire from the frog.)
- General Wiring Topics for DCC
- Types of Turnouts
- Methods of Operating Turnouts
- DCC Friendly Turnout
- Wiring Diamond Crossings, Slips, Scissor Crossings, etc.
There are a number of data sheets, in various languages, available on the PECO Technical Page. This link goes to the English Code 83 Electrofrog turnout. OO/HO Gauge Electrofrog Turnouts/Crossings (Code 83)