Good Morning. Today we bring you an exciting assembly for anyone who can not or does not want to buy a smoke sensor for the house. This smoke detector circuit is something straightforward that can be done with a 555 circuit and a photoelectric sensor.
The photoelectric sensor module is used as the smoke detector, while the 555 is configured in an astable mode as an oscillator to sound the alarm through a loudspeaker, which can be a PC Speaker of an old computer tower. Basically what we are building with this circuit is a light barrier and a buzzer or noise emitter. In the absence of smoke, the LED light of the photoelectric sensor goes directly to the phototransistor through the slot. In this way, the collector of the phototransistor releases the current to earth. This causes pin number 4 of the 555 to be at a low voltage level, so the timer resets and the alarm does not sound.
With this system, it will be possible to configure the thresholds for dangerous temperatures, the limit values for humidity through pushbuttons. When the system detects a critical threshold, a red led flashes and more abuzz sounds.
To make this detector, you will need the following list
- 1 Arduino Mega 2560
- One humidity and temperature detector DHT11
- One methane gas detector MQ-2
- 1 LCD
- One buzzer module
As well as some electronic components such as switches, LEDs, jumper cables, one potentiometer of 100Kohm, one plate lab deck, one resistance of 1Kohm and supply of 5V.
SCHEME OF SMOKE DETECTOR WITH PHOTOELECTRIC SENSOR:
But when the smoke passes through the hole of the photoelectric sensor, the LED light stops coming to the phototransistor. Then, the phototransistor stops transferring the current to ground and pin4, which is the RESET of 555, goes high. At that time the alarm starts to sound. It must be taken into account that, to allow the smoke to reach the photoelectric sensor, and that this circuit work properly, in the box where we are going to place the circuit, holes must be made, otherwise the smoke will not pass through the sensor, and can burn troy, that the pot that will not sound even remotely. This assembly requires a minimum of 9 and 12 volts to operate.
The demonstration video is available at the end of the article.
You can finally rest easy thanks to the world of DIY and have your wallet more filled.