This page shows an automatic Reversing Loop - Switch Machine control circuit for stall motor or twin coil type switch machines.
The stall motor switch machine used to develop this circuit is the Circuitron - Tortoise™ (Model number 800-6000) slow motion type switch machine motor.
This circuit should be able to operate any twin coil switch machine but the machine must have at least one set of auxiliary contacts.
The circuit uses one set of the switch machine,s auxiliary contacts (#2, 3 and 4) to allow the circuit to remember its last position when power is applied to the circuit. A second set of auxiliary contacts are available for other functions (#5, 6 and 7).
The circuit above can be coustructed using the 8 Photo-Detector PCB - Inverting circuit board and the 556 Timer Stall-Motor Switch Machine Driver circuit board.
It is not the purpose of this page to provide a detailed explanation of the IC's used by this circuit. If you want more information on this subject please refer to the Flip-Flop Made With A LM556 Timer Chip page in the miscellaneous circuits section of this site and also the Visible Light Photo Detector Circuits.
The circuit uses the basic phototransistor detector circuit to sense the position of a train that is approaching or is in the reversing loop.
Track polarity reversing is not covered by this page and will have to be determined by the user.
A printed circuit board will be available for this circuit in the future.
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 December, 2011