Modifying Peco Points for DCC
Rick Fletcher - NSW Australia
Updated 3 Aug 2016

Peco Electrofrog point modified for DCC. I have added the microswitch to the right which changes the polarity of the frog as the point changes. The microswitches were about 50c - $1 on eBay and are activated by the push rod controlled either by mechanical point levers
or by servos. On this page "Point" = "Turnout"   "Sleeper" = "Tie"
The microswitches need to be small - these are 20mm x 10mm x 6mm thick (body size)
These were the microswitches I used but ... ... the longer arms on these may have been better (can be trimmed)

The first step is to attach the microswitch in exactly the right spot as shown below. The critical bits are:

  • I always fit the microswitch such that the electrical switch contacts are towards the "Right" rail which is always a RED wire on my layout. The same connection (the centre one on the switch) goes to the Right rail - clarified further down in the YELLOW BOX
  • the hole in the throw bar must be able to operate the lever on the microswitch (and NOT miss it!)
  • the switch needs to be positioned so that the throw bar will operate the switch (hear it "click") when the points are thrown.
  • the switch is attached using contact cement (in my case Quick Grip). First work out which surfaces of the point and the microswitch will need to be scraped or filed smooth. I scrape the underside of the point with a blade and file the bottom side of the microswitch to level it.
  • make sure you don't get glue into the moving parts and hold it with a clamp as in the photo below.
Clamp the microswitch in place for a few hours.
The two bridging wires here need to be prised out. Check the instructions with new points or on their website.
The easiest way to lever the two short wires with a small screwdriver. Then put a small amount of flux on the 4 rails below
The 4 rails have have a spot of solder to "tin" the rails and on the left a piece of tinned copper wire has been soldered in place.
The rails on the left are bridged and trimmed; the wires in the middle removed; and attention moves to the frog connection on the right.
The wire provided needs to be extended to reach back to the microswitch. Use similar size tinned copper wire. Here the extra wire has been twisted around the original and will be soldered then run down the length of the point.
This diagram explains what is happening electrically. In my method, the switch becomes part of the point to feed the correct polarity to the frog.
An additional wire from the Common connection on the microswitch is taken below the layout to be used to indicate which route is set on the panel.
The wire has been soldered and is run in the least conspicuous path. I gently melt the wire into the underside of the sleeper to hold it in place.
The wire from the frog terminates at the Common connection on the switch - may be labelled "C" or "1"
This rail has been tinned ready for connection ...
...and this one ready for the other side.
As the run is only a few mm, tinned copper wire is fine.
Another view.
These wires run through the foam benchwork and connect to DCC (red & green) and the 3rd wire provides a common connection to allow an indicator to show which way the points are set.
The LH connection is the common pole in the SPDT switch.
The middle contact connects to the red (Right rail DCC wire) and the RH contact connects to the Left rail.
This template locates the cut-out needed to accept the microswitch under the point.
The red lines are used to align it to the rails as the switch is off centre.
Having marked out the position of the recess for the microswitch, cut the underlay and foam with a sharp knife.
Routing the hole to a depth of 10-12mm with a Dremel (and vacuum cleaner).
Ready for a test fit.

The final steps which can be done after the point is installed:

  • remove the over-centre spring IF you are using servos to control the point - this can be done from the top.
    My points are operated using servo control technology designed by the MERG UK group and built by the user. The points operate at a slow speed and can be set up using a computer interface to smoothly touch the stock rail. See MERG site.
  • leave the spring in place if you are manually switching the point
  • notice that the sleepers near the mechanism have been thinned down from their over scale size
  • if servos are used, the throw bar ends can be cut off.
  • weathering will improve the realism of the installed point.