Arduino Based Hourglass
![hour.jpg](/proxy/?url=https://content.instructables.com/F83/KB9Q/L947T9EA/F83KB9QL947T9EA.jpg&filename=hour.jpg)
![ckt.jpg](/proxy/?url=https://content.instructables.com/FCB/M0J8/L7NCILH2/FCBM0J8L7NCILH2.jpg&filename=ckt.jpg)
![Electronic hourglass made with tinkercad](/proxy/?url=https://content.instructables.com/FRI/IYLV/L7NCIOIM/FRIIYLVL7NCIOIM.jpg&filename=Electronic hourglass made with tinkercad)
![hour.jpg](/proxy/?url=https://content.instructables.com/FUO/W119/L8VN5RZR/FUOW119L8VN5RZR.jpg&filename=hour.jpg)
This is a project that is functional and working so that anybody can make a real one. I had made the same circuit using attiny2313.
https://www.instructables.com/Attiny2313-Based-Electronic-Hourglass/
This was a little complex circuit to teach younger kids, considering the programming of the attiny chip and soldering all the LEDs and connecting them. So I made another one using arduino it will be easier for kids of grade 3 and above. Yes, I teach as a hobby.
Supplies
Nothing more than your hands, a computer and an internet connection.
Truth Table
![truth table.jpg](/proxy/?url=https://content.instructables.com/FGR/UEXZ/L7NCILGV/FGRUEXZL7NCILGV.jpg&filename=truth table.jpg)
The truth table for the circuit can be seen in the adjoining figure. I have planned to connect the LED's in a way so that single pin can be used for the top and bottom triangle. You can understand the circuit in the next step.
Circuit
![circuit.jpg](/proxy/?url=https://content.instructables.com/FW6/F7HV/L7NCILGT/FW6F7HVL7NCILGT.jpg&filename=circuit.jpg)
Circuit is simple single pin is used to control 2 different LED's. Make sure the VCC is always connected to 3.3V. Connecting it to 5V makes both the LED's to light up and defeat the circuit's purpose.
Basic step: When pin is high one LED glows and when pin is low other LED glows.
![ckt.jpg](/proxy/?url=https://content.instructables.com/FS7/1IQG/L7NCILGU/FS71IQGL7NCILGU.jpg&filename=ckt.jpg)
![Electronic hourglass made with tinkercad](/proxy/?url=https://content.instructables.com/FIL/JL6U/L7NCIOJD/FILJL6UL7NCIOJD.jpg&filename=Electronic hourglass made with tinkercad)
![hour.jpg](/proxy/?url=https://content.instructables.com/FCR/OL76/L8VN5S01/FCROL76L8VN5S01.jpg&filename=hour.jpg)
Using the Above 2 steps start connecting the LEDs to the arduino.
For programming no complexity in loop function are used. Only straight program with delays are used.
Basic step: When pin is high one LED glows and when pin is low other LED glows.
Finally it is done. All working. Check the video for the functionality.