Assalamualaikum WR. WB. How are you friends, hopefully you are always in good health! In this video, we will make a simple gas and smoke leak detector without Arduino, namely using the MQ-2 gas sensor. sensor module costs only Rp. 15,000 friends, it's very cheap Before we continue, I want to inform you that the WFH20 now has an online shop at Shopee For friends who need electronic components, modules or sensors for microcontrollers Please visit the WFH20 Official Store at Shopee Get the lowest price at WFH20 Shopee Store Don't forget, use the free shipping voucher and follow us at shopee. MQ-2 sensor works at 5V DC. It can measure and detect flammable hydrocarbon gases such as LPG, alcohol, propane, hydrogen, methane and can also detect smoke gas sensor MQ-2 contain sensitive material tin oxide or SnO2 in clean air or in normal air, has a conductivity that is low when the surrounding environment contains flammable gases conductivity sensors will increase with increasing concentrations of flammable gases in the air with a simple circuit, this tool can detect The conductivity changes due to the concentration of gas in the air. When turned on, it takes about 20 seconds to warm up So, don't be surprised if the sensor feels a little hot. This is normal, due to the heating of the wire inside the sensor internals. There are 2 LEDs as power indicators and output indicators in the MQ-2 sensor module, then there are 4 pins, namely the VCC pin, Ground (GND), DO (Digital Output) and AO (Analog Output) Output that we use (In this video) is from the DO pin. This sensor module uses the LM393 IC and a trimpot (trimmer potentiometer) to adjust the sensitivity of the digital pin. So friends, what can be adjusted with this trimpot (trimmer potentiometer) is not the sensitivity of the sensor but the digital pin. So we can set how long this digital pin output will be active. I use a buzzer is activated with intermittent or sound drop out is the output of which serves as an alarm when the sensor detects gas leaks and smoke Then, I added the switch touch sensor TTP223 With the configuration points A and B are connected serves to mute the sound of the buzzer when DO actively So, when we are on standby in the gas leak area However, so that there is no panic, the buzzer sound or alarm sound can be turned off using this touch sensor switch. However, you don't have to use this switch only. you can use another switch or if you don't want to use the switch it doesn't matter if you are curious about how this touch switch works, please watch my video before check the description or from the card on the top right, then there's Dot PCB or PCB There is already a hole like this and the female pin header 4 foot now we continue to assemble the component components. As in the following circuit image first, we solder the header pin. The header pin functions as a holder or socket for the MQ-2 so ... this sensor module is unnecessary soldered, so that if this sensor module is damaged, we can easily replace it then I add this USB cable to function as input power so that later we can connect it directly to the HP adapter (Handphone) or power bank, the positive cable is connected to the VCC pin and the negative is connected to GND or Ground on the MQ-2 sensor TTP223 touch switch which has been attached to the pin header is soldered to the PCB Install the buzzer cable to the PCB with the positive buzzer connected to the TTP223 output pin and the negative connected to the GND TTP223 pin Then, add 2 cables for the jumper from the 5V power input to the VCC TTP223 pin and the jumper from the DO pin of the MQ-2 sensor to the GND TTP223 pin I use powerbank as the power input, it is optional. So without any power bank, this tool can also be directly connected to a 5V cellphone adapter then adjust the position .. Just adjust it .. it doesn't have to be similar to what I made, please develop it yourself. It's time for us to test this tool. First, I tested with a gas lighter. gas content contained in this gas lighter is a liquid hydrocarbon such as naphtha and buthane then we try to detect smoke. Finally, we try this tool to detect LPG gas. As I said earlier you can also be directly connected to a 5V adapter without using a power bank. Well ... in conclusion, this gas and smoke leak detector can work properly with a simple circuit and at a very low cost. we've been able to create a gas leak detector and the smoke detector of the three objects that we test, these sensors are very good at detecting gas and smoke So .. this could be one option to safeguard our homes Especially for early detection of LPG gas leakage video A few times this, hopefully useful. Don't forget to subscribe and activate the bell too, so you always get the latest updates from this channel Wassalamualikum WR. WB.