This simple smoke detector project uses two main ICs: the MOC7811 optical sensor and the LM358 operational amplifier. It can detect smoke in the air and alert you by lighting an LED and sounding a buzzer.
Components Required
- 1. IC MOC7811►https://amzn.to/3BGFqLk
- IC LM358►https://amzn.to/3BLKbmG
- Transistors-BC547-(2)►https://amzn.to/3h2gRAy
- Resistors-100Ω-(1), 33KΩ-(1), 10KΩ-(2) & 680Ω►https://amzn.to/2YuNHDS ►https://amzn.to/3BFdurh ►https://amzn.to/3kUd3Tc ►https://amzn.to/3kUWHtr
- LED-(1)►https://amzn.to/3jIzrzy
- Buzzer-(1)►https://amzn.to/2WMlKGJ
- Variable resistors(potentiometer)-4.7KΩ-(1) & 10KΩ-(1)►https://amzn.to/3yG7psN ►https://amzn.to/3kVGNyX
- Capacitor-100µF-(1)►https://amzn.to/3BKcbHC
- 9v Battery►https://amzn.to/2WVegRF
- Zero PCB►https://amzn.to/3yNBMxc
Circuit
How It Works
- The MOC7811 sensor shines infrared light inside a small gap. Normally, no smoke means light passes through without scattering.
- If smoke enters the gap, the light scatters, changing the sensor’s output signal.
- This signal goes to the LM358 op-amp, which compares it to a set reference level (adjustable via potentiometers).
- When smoke is detected (signal crosses threshold), LM358 activates transistors that turn on the LED and buzzer.
- The LED lights up and the buzzer sounds, alerting you to smoke presence.
Watch the full video tutorial here: How to Make a Smoke Detector Project using IC MOC7811 and LM358 at Home | DIY