It can be employed in places such as kitchens, industries, welding shops, commercial kitchens, etc. Afterward, the fan gets turned off automatically too. When the relay coil gets energized then it attracts a common lever to normally open contact and the supply flows through it. If the smoke rises then the op-amp output will rise to 4V and the Q1 becomes a closed-to-turn-on or Active state, so the relay coil gets ground supply. When there is no smoke the op-amp output will be near 0 volts and the Q1 stays in a cutoff or open state, so the relay coil doesn’t get ground supply. Hence the collector and emitter will be left open (Reverse biased) when the base pin is held at the ground and will be closed (Forward biased) when a signal is provided to the base pin. The output of the op-amp is connected to the switching transistor Q1 (S8050) base terminal, this transistor acts as a switch in the relay coil terminal. Here this op-amp is configured as a comparator circuit and the sensitivity of this circuit can be varied by VR1. ![]() Variable resistor VR1 is connected between the +9V DC supply and the variable terminal, which is connected with inverting input of the op-amp. Further two sensor terminals, A are connected toward the operational amplifier (LM358) non-inverting input, and another heater terminal H is grounded. And the SPDT relay coil is also connected with a +9V supply. As the circuit operates with a 9V DC supply, sensor pins B, H, and B are commonly connected to a +9V supply. ![]() Here it has six terminals, two middle terminals are connected to the inner heater component and the others are terminal A and terminal B (sensing element). It uses a heating element to detect smoke and this sensor’s conductivity rises along with the smoke or gas level rising. Now as we have used MQ-2 Sensor, it has good sensitivity to combustible gas and smoke. LED1 (Green) indicates the power supply status. Then a positive voltage regulator, IC 7805 is employed to regulate the 9V DC into 5V DC. Then 470μF C1 capacitor is placed as a filter, which removes the AC ripples in rectified DC. Here four 1N4001 diodes are employed to convert the 9V AC supply into a 9V DC supply. For this, a rectifier is used, and a 230V AC supply is stepped down to 9V AC by using a step-down transformer. So first we have to convert 230V AC to 9V DC. Working ExplanationĪs we can see in the circuit, we need a 9V supply to operate. It has a maximum gain value of 400, this value determines the amplification capacity of the transistor. S8050 is a low voltage high current small signal NPN transistor, designed for Class B push-pull audio amplifiers and general-purpose applications. 2 Channels 20mA per Channel 30nA 70 dB Instrumentational OP Amps 15V 5V30V ☒.5V15V MC1458 8 Pins 8-DIP (0.300, 7. This is a three-terminal NPN silicon transistor. MC1458N Operational Amplifier: Pinout, Specification, and Datasheet. It has six terminals, two middle terminals are connected to the inner heater component and the others are terminal A and terminal B (sensing element). And conductivity of this sensor rises along with the smoke or gas level rising. MQ-2 Sensor has good sensitivity to combustible gas and smoke, this sensor uses a heating element to detect smoke.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |