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Circuits4Tracks is a small company which produces a number of devices, available in both assembled and kit form.


  • Quad Occupancy Detector
  • Switch Machine Interface
  • Signal Animator
  • Grade Crossing Controller
  • The Traverser
  • Fast Clock Display

Quad Occupancy Detector

Current-sensing occupancy detector works with both analog and DCC layouts. Four detectors are on a single circuit board to bring the cost per detector lower, however it is possible to only populate part of a card if one, two, or three detectors in one location is practical.

Electrical isolation between your track power and the circuit the detector feeds into is a good idea. Our detector accomplishes this by using optical isolation.

Switch Machine Interface

This device provides a reversible card-edge connector to attach it to a Tortoise switch machine and has separate connectors for its motor and the two sets of SPDT contacts. The reversible feature means that it can be connected either way to a switch machine and the wiring connections remain the same.

A 2-position screw terminal block provides connections for the motor power, and a 3-position terminal block provides connections for the traction power for an electrified frog, with the centre terminal being the common terminal.

Either a 3-position terminal block or a 3-pin header is available for the second SPDT contacts, with the header option provided for easier connection to a digital system, including our future signalling product, Signal Master Plus.

Signal Animator

The ability to have signals with speed indications can involve a daunting circuit if performed in hardware. Software drastically simplifies this, but requires a significant number of outputs. Add to this is the choice of signal styles: 3-colour versus searchlight and the way to wire them: common positive or negative.

We have designed a signal driver around a PIC microcontroller to get the best of both worlds. The Signal Animator does all this with the flexibility of being usable for searchlight and three-colour signals, wired common positive or negative.

Grade Crossing Controller

Grade crossing signalling activates when a train approaches from a distance, and continues to remain active until the last car of the train clears the crossing. If trains only passed in one direction, a single occupancy detector could activate crossing signals directly. When trains move in either direction, things become more complicated.

For bidirectional traffic, three detectors are needed: one for each approach on either side of the crossing, and the short section over the crossing itself. In one direction, signals are activated when one approach is occupied and remain active until the section over the crossing has cleared. In the other direction, signals are activated when the other approach section is occupied and remain active until the section over the crossing has cleared.

Our Grade Crossing Controller, or GCC for short, takes the occupancy information from three detectors (or six, for a double-track line), and determine if the crossing signals should be active or not.

The Traverser

Analog Only

The Traverser is a circuit that automatically operates a DC powered train back and forth along a section of track, stopping for a user-configurable duration at each end. Operation of the Traverser requires the use of some form of block detection.

Fast Clock Display

This product is for use with a DCC system by NCE.

DCC systems from NCE have a fast clock feature where the command station allows setting the time, time format (12 or 24 hour), and a fast clock ratio (1 to 15). Cabs with an LCD display are able to show this time on the right side of their top line of text. See the image to the right.

We have created a product that listens on NCE's cab bus for the broadcast of this time value and displays it on an easy to read LED display. This product includes a faceplate as it is designed for installation in the fascia of the layout. It has two RJ-14 jacks on its backside for installation in line with the cab bus, and one RJ-14 jack on its front for plugging in a cab.