This fun project teaches the principle of measuring. Given a number displayed on an LCD, one must find the same measurement using the slider in the front. Correct measurements will set off an LED.

Supplies

Components:

Qty 1 Ultrasonic Sensor

Qty 1 3V LED

Qty 1 Arduino board

Qty 1 LCD Screen

Qty 1 Switch

Qty 2 Mini Breadboard

Other Materials:

1/4in Wood

Duck Tape

Jumper Wires (variety)

Qty 3 6in Craft Sticks

Step 1: Wiring

First step, is to wire all the components. Wire the Ultrasonic sensor on one of the mini breadboards, with the echo pin connecting to pin 8 on the arduino and the trig pin connecting to pin 7. The send the Gnd pin to one of the ground pins on the arduino.

Then wire the SCL pin on the LCD to the A5 pin and the SDA pin to the A4 pin on the arduino. Then, to simplify, connect the Vcc pin on the LCD, back over to the mini breadboard with the Ultrasonic Sensor, so that now you can connect that wire as well as the Voltage pin on the Ultrasonic sensor to the same 5V pin on the arduino. You can also connect the Gnd pin on the LCD to another of the arduino’s ground pins.

Now to add in the LED and a switch to power it, Remove the 5V pin just from the arduino and run it through a switch before coming back to the 5V pin. Plug in an led to pin 10 on the arduino and then back to ground on the second mini breadboard.

Step 2: Code

Now you can plug in your arduino to a computer and upload this code that will allow the LCD to display a random number, and set off an LED when the correct measurement is recorded by the ultrasonic sensor.

Step 3: Laser Cut

Now to cut the housing for your components you can use here cut files for the housing of the ultrasonic sensor, as well as the LCD Screen. There is also a board for the base.

Step 4: Construction

Put the box’s together with wood glue. The use some duck tape to secure the LCD Screen in slot in the LCD encasing box. Then fit the Ultrasonic Sensor into the the two circle holes and glue down the boxes with the wires escaping the enclosures through the little doorways out of the boxes.

Step 5: Wrapping Up

Now you can take more of the duck tape to start covering up the rest of the components making sure to leave a space in the back for your power pack cables, and/or your cable to plug into a computer. You also need to not cover up the LED or switch as those components need to be readily accessible.

Step 6: 3D Print

Now 3D print the file below for the slider. Now using the craft sticks, make a little shaft for the slider to sit on to reach the height of the ultrasonic sensor. Glue these components on and you re all set. Once plugged in, the LCD Screen will display a random number in centimeters, which you can then measure using the sider.