PERANCANGAN ALAT UKUR GAS HIDROKARBON (HC) DENGAN MENGGUNAKAN SENSOR MQ-4 BERBASIS MIKROKONTROLER AT89S52

Abstrak Telah dapat dirancang alat ukur gas hidrokarbon menggunakan sensor MQ-4. Kadar gas yang terdeteksi diolah untuk ditampilkan pada seven segment melalui beberapa rangkaian, yaitu rangkaian sensor, rangkaian komparator, penguat tak membalik, rangkaian ADC0804, sistem minimum mikrokontroler AT89S52, dan rangkaian seven segment multiplexing. Seluruh rangkaian diaktifkan oleh catu daya 5 VDC, -15 VDC dan +15VDC. Rentang pengukuran alat ukur adalah mulai dari 0 ppm sampai 131 ppm. Cara kerja alat rancangan ini memanfaatkan karakteristik sensor MQ-4 yang memiliki perubahan tegangan keluaran sebanding dengan perubahan kadar gas yang dideteksi. Rangkaian komparator digunakan untuk mengatur tegangan keluaran sensor agar bernilai 0 Volt ketika mengukur 0 ppm gas HC. Karena perubahan tegangan yang terjadi sangat kecil, yaitu 2 mV, maka diperlukan penguatan tegangan sebesar 10 kali agar perubahan tegangan keluaran dapat dikonversi menjadi data digital oleh ADC0804, kemudian hasil konversi dikirimkan pada mikrokontroler. Data yang diterima oleh mikrokontroler AT89S52, kemudian diolah menjadi keluaran kadar gas yang ditampilkan pada seven segment. Kesesuaian alat rancangan dengan alat pembanding yang diperoleh dari hasil analisa regresi linier data pengujian alat rancangan yaitu sebesar 99,9%. Kata Kunci : sensor MQ-4, ADC, mikrokontroler, seven segment. Abstract It has been designed a hydrocarbon gas measuring instrument using the sensor MQ-4. Gas levels were detected by the sensor is processed for display on seven segment through several circuits, the sensor circuit, comparator circuit, non-inverting amplifier cicuit, ADC0804 circuit, the minimum system microcontroller AT89S52, and a circuit of seven segment multiplexing. The entire circuit is powered by a power supply 5 VDC, -15 VDC and +15VDC. The measurement range of measuring instruments is ranging from 0 ppm to 131 ppm. The workings of this measuring instrument utilizes the characteristics of the sensor MQ-4 that has a change of output voltage proportional to the change of gas levels were detected. Comparator circuit is used to adjust the sensor output voltage to be 0 volts when measured 0 ppm HC gas. Because the change of the output voltage is small, that is 2 mV, it would require 10 times voltage gain to make the changes of the output voltage can be converted into digital data by the ADC0804, then the conversion result is sent to microcontroller. The data received by microcontroller AT89S52, then processed into the output levels of the gas that displayed on seven segment. Compatibility between measuring instrument and reference instrument were obtained from linear regression analysis of data from test the measuring instrument that is equal to 99,9%. Key Words : sensor MQ-4, ADC, microcontroller, seven segment..