The CKT-IRSENSE is a reflective infrared proximity sensor, designed primarily for model railroad use, utilizing the latest in proximity sensor technology. It can be used to trigger a variety of sound and visual effects as well as provide track occupancy status. The sensor’s small size (0.25″ x 2.25″) makes installation simple with only a single 3/8″ hole required. The technology used in the CKT-IRSENSE makes it highly tolerant of background lighting conditions, thus requiring no user adjustments.
Price: $22
Quantity discounts available in the Iowa Scaled Engineering Store.
Applications
- Activate grade crossing signals
- Trigger a sound event using a CKT-SQUEAL sound player
- Simulating a spring switch using an MRServo switch machine
- Block detection for signal systems
- Occupancy detection on hidden tracks
- End-of-track indication in hidden staging yards
- C/MRI track occupancy inputs
How It Works
At the top of the device are two small lenses – one emits a series of infrared pulses, which are then reflected by objects into the other lens, a receiver. By measuring the intensity of the returned pulses, the sensor can detect the presence and distance to an object.
The device automatically compensates for background lighting, eliminating false triggers.
Electrical Connections
The CKT-IRSENSE needs 5-24 volts of clean direct current (DC) power to operate. Two opposite polarity, open drain (also known as open collector) outputs are available with variable release times up to 20 seconds. When the sensor is activated, one of the outputs shorts to GND while the other output is open. When not activated, the outputs are in the opposite states. Each output is capable of driving loads up to 250mA at 40V. This allows interfacing to a wide range of devices such as logic level inputs, LEDs, and even directly driving relays.
Delay Times
The activation time is preset to 0.1 seconds. The outputs will indicate that an object has been detected if the object is present over the sensor for 2 consecutive readings spaced 100ms apart. This helps eliminate errant readings. As a consequence of this, though, there will be a slight (0.1s) delay for an object being detected. For most model railroad applications, this is not an issue. If longer (or shorter) activation times are required, we can provide custom programmed devices. Please contact us with your requirements.
The release time is preset to 0.1 seconds. The outputs will indicate that an object is no longer detected if the object is not present over the sensor for 2 consecutive readings spaced 100ms apart. This can be used to debounce the detector outputs to stop the outputs from toggling, for example, in the spaces between rolling stock as it travels over the sensor.
Longer release times are available by connecting a resistor between the yellow wire and ground (black wire). See the user manual for details.
Sensing Distance
The CKT-IRSENSE is pre-calibrated to a typical detection range (~1.5”) and needs no user adjustment for most applications. However, the detection distance will vary based on the reflectivity of the object being sensed. If other ranges are needed, contact us for custom programmed devices. The detection range can be adjusted from approximately 0.5” to 3”.
Installation
Installation is easy, requiring only a 3/8″ diameter hole below the track. The sensor itself can be located between ties, making for a very discrete IR sensor solution. To secure the sensor to the benchwork, a variety of methods can be used, ranging from hot glue to a mounting bracket.
Mounting Bracket
A simple mounting bracket can be made from a 1/4″ cable clamp (IDEAL 772835L works well), a 3/4″ inside corner brace, a #8 nut and bolt, and some double-sided tape.
To begin, place the CKT-IRSENSE PCB in the 1/4″ cable clamp.
Attach it to one leg of the corner brace using a #8 bolt and nut.
On the layout, place a piece of double sided tape where the corner brace will contact the bottom of the benchwork. Carefully position the assembly inside the 3/8″ hole and check for alignment. Make sure nothing obscures the lenses on top, such as ties or ballast. With the corner brace pressed onto the double sided tape, this is a good time to temporarily connect power and make sure the sensor behaves as desired.
Once satisfied, attach it permanently to the benchwork with a screw through the corner brace.
