The Iowa Scaled Engineering Interlocking In A Box is a simple solution for adding automatic or manual interlocking signals where one track crosses another at grade (a diamond). Stand-alone automatic interlockings were common, particularly on granger roads in the midwestern US where competing branchlines criss-crossed running to every little dot on the map. Some of the larger ones had towers and operators controlling them, but many were simpler operations that involved automatic signals where the first train to approach - or the first crew to unlock the cabinet and push the button in manual cases - would get a signal to cross. The Interlocking In A Box helps add this sort of operational interest to your layout - a way to slow down your operators from just barreling across that diamond without a care in the world.

This version concentrates on the core use case - a simple, single track crossing where one track is an operational part of the layout and the crossing track is not - and the goal is to force your crews to slow down, wait to get the light, and then proceed. It's designed to be easy to install and configure - the detectors just plug in, configuration of delays is done by switches on the board, and signals just connect into the terminal blocks.

Features

• Simulates an automatic or manual interlocking at a diamond
• Designed for simplicity and to cover most use cases
• Triggered by either TrainSpotter optical detectors (automatic interlocking) or pushbuttons (manual interlocking)
• Controls a 2-aspect signal capable of displaying stop and clear (typically red and green) in each direction on one track
• Optional delay time (fixed or randomized) between arrival and green signal
• Compatible with both common anode (positive) and common cathode (negative) signals
• Realistic signal fading during changes for both tri-light and searchlight style signals
• Simple plug-and-play compatibility with most Atlas HO and N scale signals
• 5V output for powering fixed aspect heads, such as red signals on the non-operational crossing track
• Includes control board and three (3) TrainSpotter optical detectors
• Powered from 6V to 24V DC, AC, or DCC power.

Specifications

Control Board: 3.75"(L) x 2.25"(W) x 0.5"(H)

Documents

The complete design files are available on GitHub.

User Manual

Schematic