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Insulfrog, Electrofrog and Livefrog Explanations!
A turnout may be described as a Point or Switch.This section is not intended for anyone wishing to construct turnouts from components or kits, it is intended to explain the terminology of a turnout with particular reference to all track supplied by Peco . It will also explain the difference between Peco Insulfrog and Electrofrog turnouts and how to alter the Peco Electrofrog turnouts to Livefrog turnouts and the benefit of doing so. The following image shows the basic terminology that will be used to describe a Peco turnout. The image after the descriptions shows the frog area of the turnout in more detail and shows the components not described on the image below.
Turnout Terminology - some essential information is contained within these definitions:
The following image shows the frog area of both an insulfrog and electrofrog Peco turnout. They are easy to tell apart by looking at the acute crossing and frog/vee. The insulfrog turnout has plastic sections in both the acute crossing and frog making the two frog rails that form the V electrically insulated, as compared to the electrofrog which is all metal and therefore the two frog rails are not insulated. The continuous metal on the electrofrog turnouts makes it much more reliable in operation as the locomotive wheel used to collect the power from the track rarely looses contact with a conductive rail ensuring high quality running.
If you are still unsure turn the item over and look at the wiring on the underside of the frog. The insulfrog turnout will have the wiring crossing over from just before the acute crossing to the frog rail as shown in the diagram below, or on modern turnouts the crossing does not occur but the wires are separately routed to and from the same places to effect a crossover bridge. Electrofrog turnouts have one continuous wire between the closure rails and the frog. This may be as illustrated in the diagram, or as an extended 'U'.
To appreciate the benefits of electrofrog turnouts it is important to understand how both the insulfrog and electrofrog turnouts work electrically.
This insulfrog description also applies to Peco and Hornby Setrack turnouts as they are unavailable as electrofrog. With power fed from the toe end the stock rails will always remain live. With the switch rail in contact with the stock rail the closure rail becomes live and using the 'crossover bridge' the correct frog rail is powered. As the frog rails are insulated, only one side of the V will be powered. Where the switch rail is not in contact with the stock rail no power will be present and therefore one rail of the V will always be electrically switched off allowing a locomotive to stand on this track as it electrically off. Hence the tie bar acts as an electrical switch using the switch rail to pick up the power from one of the stock rails. This is also why the back of the switch rail blade and the stock rail get dirty as they suffer a small electrical arc each time the turnout changes which causes a small dirt spot to develop.
Again assuming power has been applied from the toe end, the electrofrog turnout works the same as the insulfrog turnout with the switch rail collecting the power from the stock rail but this is where the similarity ends. Once the switch rail is live, it passes the power to the closure rail which is bonded to the V and opposing closure rail making all rails live to one polarity except the opposing stock rail. The image below shows the electrical working of an electrofrog turnout in both positions. The diagram also illustrates two possible issues with electrofrog turnouts:
LIVEFROG - Why alter a brand new turnout?
Peco electrofrog turnouts can be altered to work in a similar manner to a hand made turnout achieving the best possible running for a little extra effort. The alterations required are shown below:
What are the benefits of this alteration?
The diagram below shows the operation of the new livefrog turnout when working with an electrical switch to change the frog polarity as the tie bar moves. The two detailed benefits above are clearly illustrated.
How do we switch the frog polarity?
Switching the frog polarity requires a simple SPDT (single pole double throw) switch connected to the stock rails as the inputs, and the frog as the output - a SPDT switch will always have three contacts where two input contacts always switch to one output contact (or in reverse one input can select two outputs). This can be a standard toggle switch requiring the user to change the toggle switch after the tie bar has moved, or automated into the movement of the tie bar by a microswitch, or more frequently by a switch attached to the point motor e.g. Peco PL-13. The diagram below shows this simple wiring. With the turnout set straight, the frog will polarise with the polarity of the red stock rail - shown by the black link between the red switch input and the green switch output. If you get it wrong (assuming you have the correct output contact) just changeover the red and blue wires.
Is this extra effort worthwhile?
Without doubt! You will see a vast improvement in the performance and reliability of your layout. It may be a little complex but you will have the running quality of the better exhibition layouts constructed with hand made track. Professional Layout Services will always recommend you have this conversion completed where possible on layouts we construct, or when we lay track for clients. Especially recommended for DCC users!
GENERAL NOTE CONCERNING SLIPS & CROSSINGS (DIAMONDS)
When planning a layout it is wise to check the standard of your rolling stock wheels if you intend to use slips or crossings particularly where finer scale track is to be used. If back to back wheel measurements are not accurate, or if the wheel has a wide tread it may cause short circuits on slips and crossings. This will be a problem with both DC and DCC control.
SPECIAL NOTE FOR DCC USERS WITH PECO ELECTROFROG SHORT OR LONG CROSSINGS (DIAMONDS) AND SCISSOR CROSSINGS.
All electrofrog crossings need some form of polarity switching on the frog or V to ensure the correct setting when a locomotive runs across. The scissors is exactly the same as it has a crossing between four turnouts. In analogue use and with some digital users a switch or relay is used to change the crossing frog polarity. DCC users can simply install an auto reverse module to automatically change the polarity as the locomotive enters the crossing. Ensure the crossing is insulated correctly on the frog rails and if it connects to other turnouts as required; then simply connect the outer crossing stock rails to the DCC ring main together with the auto reverse module inputs, then connect the module outputs to the crossing frogs - one to each frog. No need for complex wiring, switches or relays!
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