Insulfrog Or Electrofrog? That Is The Question!!

There's been quite a bit of discussion on the merits of the Peco Insulfrog versus the Peco Electrofrog with both the Electrofrog and Insulfrog getting a lot of bad press.  All of this "dissing" the Insulfrog and the Electrofrog seems to be coming from commentators who have never closely looked at these two brands of Peco turnout.  And new commentators to the scene get their information from previous commentators and so the bad reputation of these two excellent turnouts continues. 

Let's take a close look at both the Peco Insulfrog and the Peco Electrofrog so that we get a very clear understanding of how "power routing" takes place on both of these beautiful DCC friendly turnouts.

For those pickers-of-nits, here's a diagram of the real McCoy with all of the naming conventions.  In the real world, a turnout is never called a turnout.  It's called a switch.

And all of those X's and Y's, Y1's, Y2'x, etc have specific lengths, depending on whether it's a #6, a #8, a #10, etc switch.

Diverging Route and Mainline Route
The three major parts of  a switch are the points, diverging route and the mainline route.  The train gets through the switch via the frog.  The mainline route is that part of the switch that goes straight ahead.  The diverging route is that part of the switch that curves.  In model railroading, we buy our switches (turnouts) as either left-hand or right-hand.  On the real railroad, left-hand or right-hand is irrelevant.  The frog is bi-directional.  The only thing that determines whether the switch will route trains to the left or to the right is the "bent and curved rails" - the stock rail and the closure rail.  To make a bent and curved stock rail, simply take a piece of track, put it in the special clamping device, and close the large bolt.  This puts a kink in the rail.  Then bend the rail to the right radius.  For the curved closure rail, simply bend the rail to the right radius.  Of course, if you're working on the prototype, a few hydraulic jacks will greatly help the situation.

But I digress.......

The "Olden" Days Before DCC
Pritchard Patent Product Company Ltd of Beer, Devon, England, introduced the Peco Electrofrog and Insulfrog in the "olden" days before DCC.  In those times, power in a siding usually depended on which way the turnout was thrown (mainline route or diverging route) and how the turnout conducted the electricity through the points.  It also depended on how the rails beyond the turnout were wired.   If you wanted to constantly have power in the siding, then you used the Insulfrog.  If you wanted the power turned off in the siding, you used the Electrofrog or a DPDT or SPST switch.  Or something like that. 

Looking from the top of the turnout, it's difficult to tell the difference between the two.  Insulfrog?  Or Electrofrog?  They both look the same. 

And then along came DCC which turned everything upside down on its head.  Only we forgot to throw our analog theory books out the window.  And so the debate on Insulfrog versus Electrofrog began. 

Wiring A Turnout In DCC
In DCC, with few exceptions, electricity is fed to all the tracks - mainline and sidings - because we control our locomotives by a decoder and a throttle and not by the tracks or DPDT switches.  That's the major difference between analog and DCC.  

So we usually wire our turnouts thus - a pair of track feeds  before the points on the turnout (red and blue wires on the left), a pair of track feeds after the switch on the mainline (red and blue wires bottom right), and a pair of track feeds after the switch on the diverging route (red and blue wires top left).  

Many commentators do their critique on the Insulfrog or Electrofrog from the workbench and not from the layout.  As I found out the hard way, there's a big difference when the turnout is incorporated into the layout!!  You can very easily blow your command station/ booster if you don't know the difference.

So, let's trace the wiring of the Peco Insulfrog

Power Routing On The Peco Insulfrog
The power routing on the Peco Insulfrog is very ingenious but very simple.  Power through the closure rails and the inside mainline and diverging rails DOES NOT come through the points.  In case you missed that I'll restate it another way.  Power to the inside and mainline closure rails and the inside mainline and diverging rails DOES NOT come through the points.  Unless you haven't followed the rules of DCC for switch wiring and wired your switch differently than stated above.  (And I don't recommend doing that!) 

Instead, the reverse is true.  Given that a welded (soldered) wire bond conducts power better than a mechanical connection (screw terminal, mechanical switch, rail-touching-rail), power to the points and the curved and straight closure rails comes from the inside and mainline diverging rails.  In the photo below, with the route selected for the main line, we've shown that path in red and blue, along with arrows indicating the direction of current flow.

And in the photo below, with the points thrown for the diverging route, we've shown that path in red and blue, along with arrows indicating the direction of current flow. 

Now take a close look at the two photos and notice the difference in current flow.  THERE IS NO DIFFERENCE!!!

And that's the beauty of the Peco Insulfrog.  Right out of the box, they are DCC friendly.  The points, the straight and curved closure rails, the inside mainline rail and the inside diverging rail are all powered with the correct polarity regardless of which way the turnout is thrown. 

"But the Frog Ain't Powered", You Say!
Right away I can hear the screams.  "The frog ain't powered!!!"  Please take a close look at the frog.  It's made out of plastic.  It ain't ever going to be powered!!

And if you take an even-closer look at the frog, you'll see that there's two pieces of plastic - about 1/16" in length at the left end of the heel-and-toe of the frog, and another right at the tip of the frog that's about 3/16" in length.

Except for the heel-and-toe of the turnout, all bits and pieces of rail are positively powered.  There is, however, that 1/2" gap between those two pieces of plastic.  And this is where the power pickup on your locomotive becomes very important.  Most diesel locomotives these days pick up power from both trucks.  And many steam locos pick up power either from the two trucks in the tender or from several of the driving wheels.  So, except for short wheel-base steam locomotives, that 1/2" gap becomes irrelevant. 

A Look At The Underside Of The Insulfrog
To understand how power gets from the inside diverging and mainline rails back to the closure rails and points, we have to turn the Insulfrog over on its back.  Immediately you will see there are two wire bonds underneath the frog.

If you follow the path of the power in the rails (the red and blue lines), it's these two wire bonds that provide the positive electrical connection from the inside diverging and mainline rails back to the inside closure rails and the points.

Yes, I agree that the point which is in contact with the rail will also conduct electricity, in which case, we have "double" positive connection (That contact actually comes from a phosphor-bronze spring tab at the front end of the point).

So, we have what we are looking for - a reliable power connection that will get our train through the turnout.  And the Peco Insulfrog does just that!

There is, however, a little caveat.  The wheels of a locomotive will sometimes short out on the inside diverging rail and the inside mainline rail.  But that's a very easy fix.  We'll cover that in the next issue of our blog.