This page has circuits that use infrared position sensors that are available from several sources. The circuit board used in the examples is shown in the picture.
The sensor circuits could be used in the place of a phototransistor where lighting condition are poor.
The IR LED and the phototransistor could be dismounted from the circuit board and connected via wires for installations such as between or across the tracks.
The 12 volt circuit could be used to control circuits such as the 2011 Automatic Grade Crossing Circuit in locations with poor lighting or for night operation.
Any number of outputs could be connected in parallel. This would produce an NOR type output.
555 Timers are shown but OPAMPS, comparators, logic ICs, and other devices can also be used as outputs for higher voltage or current applications, etc.
The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.
If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.
Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.
15 January, 2019