Arduino project · Fire, gas and safety · Medium
Gas Level Bar with Alarm
The bar shows how much gas is in the air. Above 70 percent a buzzer sounds.
What you will learn
- How to show a safety sensor as a bar
- Why alarms need a threshold
- How people see danger at a glance
How it works
The gas percentage is mapped to the bar. A second step switches the buzzer on above 70 percent.
Try this next
- Switch a fan relay at 50 percent.
- Make the last four LEDs red.
- Send an SMS above 70 percent.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A kitchen gas alarm
Raise the gas level. Smoke fills the real room and the alarm goes off.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Gas sensor = gas in the air
- Buzzer + LED = the alarm