This page serves as documentation for the circuits that I have built which make use of the Modular Signal System first documented by Gregg Fuhriman in Railmodel Journal, and further documented on the Free-mo.org website.
This effort was an experiment on my part in designing and building a circuit board for the circuits involved. This effort documents two circuit board designs, one for cascade modules, where signals are located, and a second for detection modules, which go between the cascade modules. These terms are further explained in the link above.
The Modular signal system requires a combination of optical and current sensing detectors for reliable operation. This is required on a modular layout becauase we cannot assume that every participant will have resistor equiped wheelsetson all rolling stock. For this project, I used Rob Paisley's Block Occupancy Detector helper as the optical detector. I incorporated a BOD helper into each of the circuit boards, along with a 5vDC power supply for powering the detectors and the signals at cascade modules.
The two circuit designs are shown below, along with the data files needed to submit the boards for production using ExpressPCB
The cascade circuit includes BOD helper and outputs to connect signals control boards for each of the two blocks the cascade module influences. The circuit details are below:
In addition to the BOD helper and voltage regulator, the Detection Module circuit includes a connection for an NCE BD20
My test configuration consists of one cascade board connected to two Atlas signal control boards, as pictured below
Testing has resulted in the following observations: