Any questions about sensors can be directed to [email protected]. We can offer suggestions using the most advanced technology to correctly solve your sensor issues.
Proximity sensors
Typically there are two types of proximity sensors. They are Beam Make and Beam Break. They are used to detect changes in light levels. Also there are two types of current sensors often used in model railroading. Each has a place in your railroad and any can be combined with any KandR Electronics modules. Most common are the standard IR and ambient light sensors.
You need to consider the application. Is it for sensing a train in a tunnel? Is it for Block management? Computer signaling? Is it for sensing a train passing through a crossing in a high ambient lighting situation? When chosen correctly you will get realistic results.
Ken Glaza
IR Sensors
Standard IR Cross Track Sensors
Our enclosed type are much like the Arduino breaker beam and the open air are just the diodes with wires. The receiver on our open air sensor has electronics further along the wire where a third wire becomes the signal wire. The electronics used is an open collector that drives the third wire to ground signaling a change in light. The change in light must be great enough to trigger the open collector to ground on the third wire.
Placement of Beam Break IR sensors should be as close together as possible and pointed directly at one another crossing the track at an angle raised high enough such that a flat car blocks the light. Crossing multiple tracks reduces the effectiveness due to the inherent short range of IR diode pairs. Also ambient light will reduce the range of this type of sensor. Concealing them in buildings will make an improvement. Or use the enclosed diode pair. Any of these can be concealed in utility cabinets or buildings that are typical track side structures.
Laser IR Cross Track Sensors
In higher ambient light situations the Laser emitter and sensor pair should be used. A laser will focus light into a concentrated beam that can cover large distances. “First reflect” type mirrors are needed so the beam is not split in the glass. Our lasers are safe low power but can reach 10 feet.
The difficulty is in the aiming of the IR laser beam. Your cell phone camera will show the beam reflected on white paper. Starting at the source move the reflective paper away from the source while adjusting the focus and direction until you hit your target.
Reflection IR Sensors
Reflector Beam Make sensors are usually placed between the tracks to reflect on the underside of a passing train but are susceptible to a high level of ambient light. Sometimes they are placed on the side of the track to reflect on the sides of rolling stock. So lower room light is best. Adding reflective foil on the under body of your rolling stock raises the trigger threshold and will help reflect the IR beam back to the receiver diode.
Ambient Light Sensors
A fourth type of sensor are ambient light sensors. They do not need a special source IR diode or laser emitter. They rely on having the room light blocked by a passing train to sense train present. These sensors are great for rooms with bright ambient light or for outside railroads. However night session might be problematic.
Current Sensors
There are two types of current sensors, an AC and a DC. AC current sensors up till now have been the most expensive of all types. An AC current sensor uses a coil. When AC current is sent through the center of the coil it produces a voltage that is compared to a reference voltage and actuates a relay or a signal wire.
AC Current Sensors
AC Current sensors work with DCC systems because DCC provides a constant AC signal of 14 volts to the rails. Current flows when a DCC equipped engine or lighted car sets on the track. To sense current feeding a track block, the power feed of the track is looped through the sensor module coil. Typically there are no ambient light issues, works over long rail blocks, above table eye soars are gone and they are most reliable. See diagram below.
I use this method more often than any other.
Ken Glaza
DC Current Sensors
DC current sensors are resistive. They measure the voltage drop across a piece of wire. If you are running a DC rail system this could be used to sense a train present when it is on a rail only if it is moving.
The IR or ambient light sensors would be a better choice than current sensors, to detect the presence of a stopped train
Ken Glaza