Bingo RC Designs Ultrasonic Clip Zone Sensor

The Bingo RC Designs Ultrasonic Clip Zone Sensor is a device that can indicate the position of an RC Drift Car as it passes through points within a drift track clip zone by illuminating up to 8 LEDs. As a car passes through a clip point, the LEDs on the device light up based on the depth of the car in the zone. When the car is at the outer edge of the zone, a single red LED lights up, as it gets closer to the back of the zone, additional LEDs light up, first orange, yellow, and then green. If the car passes through the deepest part of the zone, all 8 LEDs will light up as green.

The sensing range can be adjusted. The default nearest range is 100mm and the default farthest is 300mm (the sensing range can be greatly extended if desired). A variable offset is added to the nearest sensing range, controlled by a potentiometer, that adds 0-200mm to the closest sensing range.

This document assumes familiarity with the Arduino Nano programming, the listed add-on Arduino components, and 3D printing.

(Check out the Key City Drift Guard Rails, which work well with these Ultrasonic Sensors)

Build instructions:

1. 3D print the .stl files. (the .stl files are in the .zip file below)
2. Install the drift_ultrasonic_wled.ino program on the Arduino Nano (you will need to install the Adafruit_NeoPixel library). (drift_ultrasonic_wled.ino is in the .zip file below)
3. Cut polycarbonate tube into 6” sections.
4. Cut LED lights into sections of 8 LEDs, and solder a 3 wire connector to the LED strip.
5. Attach the LED strip to led_support (use the adhesive strip on the back of the LEDs), and make sure the wires are toward the base of the support.
6. Glue the support_clamp to the base of the support, bridging the wires. Insert into the polycarbonate tube (should fit snugly, no need to glue in place).
7. Glue tube_cap to the top of the tube.
8. Glue the led_socket to the top of the lid.
9. Bend the connector leads on the Ultrasonic sensor about 90 degrees so they point down (this is to clear the lid on the box).
10. Insert the Ultrasonic connector into the box, with the at the top. Hold in place with a small piece of foam (or you can hot glue, if you wish).
11. Solder wire connectors to the Arduino Nano as described below. Several wires will need to be attached to +5V and Gnd. I used a pigtail wire and a wire nut to combine all the leads.
12. Solder a matching 3 wire LED strip connector to the Arduino
13. Solder a section of power wire to the Vin and Gnd of the Arduino Nano. Make it long enough to go out of the hole in the back of the box.
14. Gather all the wires and feed them under the Ardunio and out the “back” (opposite of the USB connector).
15. Insert the Arduino into the box and hold it in place using the lock_plate piece and a M3x8mm screws
16. Attach the Potentiometer to the box using 2 M3x8mm screws
17. Connect the wire leads to the Potentiometer and Ultrasonic sensor, Connect all the +5V and Gnd leads together.
18. Feed the wires from the LED tube into the top of the led_socket and seat the LED tube into the socket.
19. Connect the LED tube to the Arduino.
20. Carefully fold up the wires and affix the lid on the box, with the LED tube opposite the Ultrasonic sensor. There is a hole in the lid for the potentiometer to protrude through and a smaller hold that provides access to the Arduino reset button. Attach using 4 M3x8mm screws.
21. Attach a Low Voltage T Tap Wire Connector to the power lead. The “T” tap allows you to run multiple Ultrasonic sensors from one power adapter by simply tapping into a main power lead.
22. Run a power lead from the 5V power adapter and clamp the T connector to it. The Ultrasonic sensor box should power up, and the LEDs should flash full green 3 times.
23. Test the sensor by putting you hand in front of it and moving it back and forth. The LEDs should light based on the distance to your hand. Adjust the sensing distance by turning the Potentiometer. 
24. (optional)The 5V PIR Motion Sensor switch can be used to turn the whole system on/off based on it sensing a car on the track. This prevents the sensors from staying on all the time. When a car passes in front of the PIR sensor, it will supply power to the bank of Ultrasonic sensors and automatically turn them off after some time if no cars are detected. (adjust to maximum delay)

Arduino Nano pin assignments

Ultrasonic sensor:

Trig = pin D2

Echo = pin D3

Vcc = +5V

Gnd = Gnd

Potentiometer:

S = pin A0

V = +5V

G = Gnd

LED strip:

Din = pin D6

Gnd = Gnd

+5V = +5V

3D print files (download .zip file below):

box.stl = main housing for the components

lid.stl = lid for box

lock_plate = small tab to hold Arduino Nano in place

led_socket.stl = socket that holds light tube (glue to the lid)

led_support.stl = support strip for LEDs

support_clamp.stl = clamp to go around wires at base of tube

tube_cap.stl = cap for LED tube

Build of Materials (amazon links)

• Arduino Nano https://a.co/d/5Rp7ajE
• Ultrasonic Sensor HC-SR04 https://a.co/d/hITetRn
• Potentiometer 10K Ohm https://a.co/d/bhBYpGp
• LEDs WS2812B IC RGB 5050SMD https://a.co/d/cLqdLyk
• Polycarbonate Rigid Round Tube, Clear, 1/2" ID x 5/8" https://a.co/d/951KYDr
• JST SM 3 Pin Connectors https://a.co/d/e7YVq4Y
• 5V 10A Power Adapter https://a.co/d/gy5Ti7W
• Low Voltage T Tap Wire Connector https://a.co/d/1z0EamA
• 5V PIR Motion Sensor switch https://a.co/d/hLldHS9
• Wire connectors https://a.co/d/aSxSZEW
• Power line wire https://a.co/d/dc4h1tx
• M3 x 8mm NHS (button head screw) (qty 7)
• .stl files for enclosure