# Drinks Low?

214

5

This is something that came to me one day when I was at dinner and I had finished my drink and was still needing something to drink. I ended up waiting about 30 minutes before the I got my drink filled.

I am also in a electronics class this is where the idea real came to life. I was going to make a coaster that would alert stuff members that I would need something to drink.

Things you need:

1. 3 cheap coasters

2. arduino uno

3. light sensor

4. leds

5. wires

### Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

## Step 1: First Step:

The first step in doing this crazy idea is to drill a hold in the center of one coaster and then hot glue the light sensor in and make sure that you do not get any over the top of the light sensor because this is the way that the arduino is going to read how low the drink is.

## Step 2: Step 2

Drill the same hole in both of the other two coasters. This is so that you can hide wires and put leds inside so that you will only get light out. This is just a idea but make sure the center coaster of the three you will be hot glueing together is clear it will allow light to come out and it will make a very cool effect.

## Step 3: Step 3

This is my favorite part this is the building of the wiring set up this will be a key part and I would recommend testing become wiring all the leds and wires through just to make sure it is working.

After this you will have to play with the light sensitivity to make sure it is right.

Hint: CODE

int LDR = 0;
int LDRValue = 0;

int light_sensitivity = 500;

const int ledPin = 3;

void setup() { Serial.begin(9600); pinMode(ledPin, OUTPUT); }

void loop() {

Serial.println(LDRValue);

delay(50);

if (LDRValue > light_sensitivity){

digitalWrite(ledPin, HIGH);

delay(10);

digitalWrite(ledPin, LOW);

delay(10);

} else {

digitalWrite(ledPin, LOW); }

}

## Step 4: Whats Next?

I want to make this into a product that a company will buy and set up with their ordering system. Which would allow me to take away the leds and it would all be seen on the ordering system.

## Recommendations

• ### Cooking Class

9,574 Enrolled