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.
Typically used are two types of proximity sensors. They are Infrared (IR) Light Beam Make and Beam Break. They are used to detect changes in light levels produced by a source of IR light. 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 using our unique 3 to 1 sensor combiner (SKU-25340016). Let’s start with the most common, the standard IR and ambient light sensors.
First you need to consider the application. Is it for sensing a train in a tunnel? Is it for Block management on a DCC system? Dead rail system? Computer signaling? Is it for sensing in a high ambient lighting situation? When chosen correctly you will get acceptionaly good results.
Ken Glaza
IR Sensors
Standard IR Cross Track Sensors
Our enclosed type (SKU-25340007) are much like the Arduino breaker beam and the open air (SKU-25340005) are just the much smaller diodes with wires. The receiver on our open air sensor has electronics further along the wire where a third wire becomes the signal wire (usually white or yellow). It eliminates the bulky package associated with the typical IR receiver making then easier to conceal.
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 and the color tempuerature will reduce the range of this type of sensor. Any of these can be concealed in utility cabinets, various vegitations or buildings that are typical track side things. This type is for only one point sensing where the light crosses the track.
Laser IR Large Area Sensors
In higher ambient light situations the Laser emitter and sensor pair should be used (SKU-25340013). A laser will focus light into a concentrated beam that can cover large distances and larger areas crossing tracks at multiple places. “First reflect” type mirrors are needed so the beam is not split in the glass. Our lasers are safe low power but can reach 15 feet or more. Our Gate kits include 2 mirrors a Laser and Receiver.
Aiming of the IR laser beam is a bit tricky. 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. All of our gate and intersection modules (SKU-57660001) feature an alignment function for fine tuning. No one has this function. It will help in alignment of any sensor we make.
Reflection IR Sensors
Reflector Beam Make sensors (SKU-25340024) are usually placed between the tracks to reflect on the underside of a passing train but are susceptible to a high level of overhead 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. These type sensors are best using them in tunnels or under bridges. Adding reflective foil to the under body of your rolling stock raises the trigger threshold and will help reflect the IR beam back to the receiver diode. These are only for a point in place sensing.
Ambient Light Sensors
A fourth type of sensor are ambient light sensors (SKU-25340023). 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 garden railroads. However night session might be problematic. These are good for point in place sensing.
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 but we have addressed that. 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.
Current Sensors For DCC
Current sensors (SKU-25340002) are AC current sensors that 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 drawing power. To sense current feeding a track block, the power feed of the track block 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 a resistive type. They measure the voltage drop across a piece of wire that is feeding a track. 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 drawwing current. Not practical for a stationary train.
These are not used often enough for me to go into details.
Ken Glaza