Block Occupancy Detector
This module detects the presence of a train and sends a signal to the Signal Controller. In addition to informing the signal controller that the block is occupied, the detector can be used to illuminate an LED on your panel board to show occupancy.

It operates on principle of detecting a minute flow of current between the rails and will detect a loco or illuminated car, marker lights on a caboose, or conductive paint across axles. To protect the rear of a train, it is necessary to have a device in the rear car that allows a small amount of current to flow between the rails.

This detector performs well with a conventional throttle (even when the power is off) or with Command Control systems such as CTC-16, PMP-112, Dynatrol, and Keller Engineering's "On Board".

The detector will perform equally well on HO, N, and Z scales and also may be used with O scale if we substitute two larger diodes ($1.00 added cost).

Its printed circuit construction with industrial grade electronic components is robust enough that there have been no failures in 10+ years of use.

The detector requires a +12 volt filtered DC isolated power supply one detector is required for each block.

Detectors are available assembled or in kit form, and if more than one kit is ordered, we will assemble one free to use as a model along with our detailed assembly instructions.

Power Supply
We can supply one power unit in an aluminum box that will deliver +12 volts DC for the signal controller and for the block detectors. The LEDs are powered from the signal controllers.

We have two sizes available: A 1.5 amp unit, which will supply 20-25 signal heads, and, for larger layouts, a 5 amp unit.

Note: The power supply does not include an AC transformer that can be purchased from Radio Shack or an equivalent source.

Signal Controller
Each controller operates two signals, one in each direction, or two heads on a multi-headed mast. The system is bi-directional on single track.

Signals perform exactly like prototype ABS (Automatic Block Signal) signals. CTC (Centralized Traffic Control) features may be added. For example, a SPDT switch added to the dispatcher's panel would enable him to set all eastbound signals red between two points during a westbound train movement.

Controllers feature printed circuit boards with industrial-grade electronic components. Wires can be soldered from either side.

Controllers require a Block Occupancy Detector to "notify" the controller if the block is occupied.

We currently manufacture and sell two different signal controllers:

• The MOD-2 Controller is a 12 volt system that will supply two signal heads with up to three LEDs "on" at a time if they are wired in series, ie. PRR signals. The values of the current-limiting resistors are changed to accommodate the number of LEDs.
• The MOD-3 Controller is specifically designed for the SA type searchlight signal using one bi-color LED. It features trim pots to achieve the color of yellow to suit your taste.

Both signal controllers provide a positive voltage to the LEDs in our signal heads. The LED cathodes are connected to the common (-) terminal. The signal system is independent of the track power.

All signal controllers are available in kit form or assembled and if more than one kit is ordered, we will assemble one free to use as a model along with our detailed assembly instructions.