PECO Unifrog

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Main article: Turnout
Unifrog detail.jpeg

Summary: The PECO UNIFROG is a new turnout design from PECO. Out of the package it will behave like the PECO Insulfrog turnout. PECO plans to replace their Electrofrog and Insulfrog products with the new Unifrog over time. Doing this allows PECO to eliminate two products and replace them with one. As of 2019 only a limited selection of Unifrog turnouts are available, but this is expected to expand with time.

There is additional information regarding turnouts in general on the Turnout page.


PECO Unifrog Announcement

From PECO:

The wiring of these new turnouts is a development of both the Insulfrog and Electrofrog designs.
For current users of the Electrofrog or Insulfrog versions of our turnouts the new Unifrog gives modellers the best of both worlds. As supplied, the turnout is wired completely “live”, except for the frog tip and wing rails, and can be used straight out of the packet without any further modification (and so behaves like an Insulfrog).
The stock rails are wired to the closure rails at the factory, which in turn are connected to the corresponding frog rail. This means the turnout is completely live (except for the tip of the frog), no extra wiring required. If the turnout is being used as a switch to isolate a section of track then it is simple job to remove the wire that joins the centre rail and stock rail and it will work like a current Insulfrog. Peco provides a pair of pigtails to allow wiring the turnout to behave like an Electrofrog. (They have been spot welded onto the appropriate places.)
To change frog polarity the PL-13 or PL-15 change-over switch/microswitch, or the SmartSwitch SmartFrog PLS-130 with do the task. A Frog Juicer or a mechanical switch would also work.

PECO Turnouts

PECO manufactures a number of turnouts in various scales.

Introduction to the PECO Unifrog

With Electrofrog and Insulfrog, modellers were able to make good looking and functional trackwork. The decision of Electro or Insulfrog had to be made at the time of purchase. After purchase, how you wire the Unifrog is up to you.

Unifrog Description

For ease of identification, the PECO part number has a U indicating Unifrog in the part number on the packaging. Example: ST-U750 is a Unifrog RH turnout, O Scale.

As shown in the picture above, the Unifrog has a metal frog, like the Electrofrog. The difference is that the Unifrog is constructed with gaps, filled with plastic, to isolate it from the rest of the turnout. Out of the package it will operate as a Insulfrog. Closer examination reveals the toe and heel of the frog are isolated from the track, so it will be dead when installed. There is a wire welded to the underside of the frog allowing it to be powered using a microswitch or other device. This will allow the phase of the frog to be controlled with relation to the switch points, like the Electrofrog. As the frog is completely isolated from the trackwork, no additional gaps or insulated rail joiners will be required on the point rails. Gaps have already been incorporated into the design of the Unifrog.

If you flip the Unifrog over, you will see that there are wires connecting the closure rails to the appropriate stock rail, eliminating the potential of a short should a wheel bridge the gap between the switch and stock rails. Perfect for DCC operations. This also eliminates a failure point, as a mechanical connection using the switch rails isn't needed for power, like the Insulfrog.

The point rails are also connected to their matching stock rails by wires under the frog, like the Insulfrog. Unlike the Insulfrog, the position of the switch rails does not control power to the point rails.

Advantages of the Unifrog Design

  1. DCC Ready, right out of the package
  2. No mechanical connections needed between switch and stock rails
  3. Dead or Live Frog operation
  4. Switch rails do not change phase depending on the frog's state
  5. Insulated rail joiners not required on the point rails to prevent a short caused by power routing
  6. Can be converted to Live or Dead frog without removal, by simply connecting or disconnecting the wire feeding the frog
  7. Only the stock rails need to be connected to the power bus
  8. Toe/heel of the frog is unpowered, unless wired. The point rails are powered.

Disadvantages of the Unifrog Design

  1. The frog is dead unless powered
  2. No power routing as in the Insulfrog, should you want to run analog (DC), as the switch rails are electrically connected to the stock and closure rails.
  3. Possible mechanical short at the point rails (wheel tread bridging gap between the point rails at heel fo frog)
Conversion to Insulfrog (Power Routing) Operation

To configure the Unifrog to route power like an Insulfrog, cut the wires underneath connecting the stock and closure rails to the switch rails. This is unnecessary for DCC operation, but can be done in seconds prior to installation. Power routing to the point rails now depends on the position of the switch rails.

What is the Difference between Unifrog and Previous PECO Turnouts?

The revolutionary aspect of the Unifrog is that you can change your mind. Install them in them as they come (a dead frog as in the Insulfrog), then later decide to convert to a live frog (Electrofrog). With the Unifrog this can be done without having to buy new turnouts. In fact, you do not even have to lift the track to re-wire the turnout, providing a hole was drilled into the benchwork for the frog wire to pass through.

Unifrog Availability

Currently the PECO Unifrog turnouts are limited in selection. PECO has released an N Scale "medium radius" SL-U395F and SL-U396F turnouts, and for HO the SL-U7061 and SL-U7062 #5 turnouts. For 00, they have released Bullhead rail products in the form of a Double Slip, Single Slip and Long Crossing. Also available is the SL-U8363 OO/HO #6 Double Slip.

As tooling is replaced, more Unifrog turnouts will come on the market.

2020 Unifrog Product Additions


PECO has announced that Streamline Code 70 #6 and #8 turnouts, and Code 100 Curved small radius turnouts will be available soon.

OO Bullhead

Bullhead turnouts in medium radius. PECO is also asking its customer base what they would like to see in the Streamline Bullhead series

Wiring the PECO Unifrog

There are two options

  1. Install it directly from the package. The frog remains insulated from the closure and point rails and requires no extra wiring
  2. Use the pre-attached wire to connect the stock rails to the frog using an electrical switch

Unifrog: Wiring for Digital Command Control

Wiring the PECO Unifrog for Digital Command Control is not much different than wiring any other turnout

  1. Connect the appropriate stock rail to the appropriate wire on your power bus
  2. Power Routing of the Frog:
    1. Attach the supplied wire to a Frog Juicer, toggle switch, Tortoise motor or other device with can switch connections to the power bus
    2. If you don't plan on doing that right away, but may in the future, attaching a short length of wire to the pigtail provided may make life easier later
  3. Optional: For reliability, connecting the switch and closure rails with a small jumper (Competency at soldering is a must here)

Power Routing

The PECO Unifrog is not power routing.

From the factory, the point and closure rails are wired accordingly for proper operation. The switch rails are also powered, eliminating the need for a mechanical connection to power them. The closure rail is also wired to the adjacent stock rail. The frog is isolated from the closure and point rails. Therefore, insulated rail joiners are not required on the point rails.

This behaviour can be changed prior to installation by cutting jumpers, as mentioned in the Conversion to Insulfrog section. LabelledTO.jpg

Help Needed

Anyone who has purchased a Unifrog can take photographs to illustrate this article. It would be appreciated.

See Also