Abra AK-325 User manual

Methane, Butane and LPG
Detector D.I.Y Kit
for detecting methane (CH4), butane (C4H10) and LPG in
household or workplace environment using the MQ2
Part Number: AK-325
Level: Intermediate

2
Description:
This kit contains the required components to build yourself a petroleum gas detector.
This module is based on a LM393 I.C. and a MQ2 sensor.
While being a simple soldering project for beginners, this kit can be used in a variety
of small personal, educational or enterprise applications such as:
Methane, Butane and LPG Detector for Microcontrollers (Analog/Digital)
Methane, Butane and LPG Detector for Arduino (Analog/Digital)
Methane, Butane and LPG Detector for Raspberry Pi (Digital)
This is a D.I.Y. kit that requires soldering through-hole components on the main single-
sided printed circuit board (PCB). Users with minimal soldering tools and intermediate
skills can easily assemble this module. The assembly process should take anywhere
between 10 to 20 minutes.
Specification:
Module
•Required Input Voltage: 5VDC
•Current: ≈ 150mA
•PCB Dimensions: 61 x 32 x 1.6mm (2.71”x 1.33" x 0.07”)
Sensor MQ2
•Environment Condition: -10°C~50°C
•Sensing Parameter: 5000ppm methane
•Concentration slope rate: ≤ 0.6

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Component
Label
Value / Type / Label
Quantity
Resistors and
Potentiometer
R1
5.1Ω/ (Green, Brown, Black, Silver)
1
R2, R5, R6, R7, R9, R10
1KΩ / (Brown, Black, Black, Brown)
6
R3
10KΩ / 103 potentiometer
1
R4
10kΩ / (Brown, Black, Black, Red)
1
R8
330Ω / (Orange, Orange, Black, Black)
1
R11
220kΩ / (Red, Red, Black, Orange)
1
Light Emitting Diode
D1, D2
3mm Red LED
2
Ceramic Capacitor
C1, C2
104 (100nF)
2
Transistors
Q1
S9012 Epitaxial Silicon PNP
1
Q2
S9013 Epitaxial Silicon NPN
1
IC Chip
U1
LM393 Dual Op Amplifier
1
PCB
----
Main PCB (Green)
1
----
Sound IC PCB (Green)
1
Modules
MQ5
MQ Sensor
1
B1
Buzzer
1
Headers
P1
4-pin Breakable Male Header
1
Bill of Materials:
This package includes 23 pieces which are listed below along with their labels and quantity.

4
Assembly:
1) In order to assemble the module, you need the following tools:
*It is recommended to have some isopropyl alcohol and a fine soldering brush handy to clean off
the excess flux on the circuit board when the soldering is done.
*ATTENTION* DO NOT USE RUBBING ALCOHOL, IT WILL DAMAGE THE COMPONENTS.
2) Open the package and verify the components. (refer to section 4. Bill of
Materials on page 3)
3) Lay down all the components on your workbench and proceed to the next step.
4) Prepare your soldering tools.
a) Use an appropriate tip for the application. Also, make sure the
soldering tip is clean. Gently use a brass wool or a brush to clean the
tip when needed. Another way of cleaning the soldering tip is to use a
wet sponge.

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b) The soldering iron temperature depends on the type of solder used.
If you are using a typical 60/40 lead solder, depending on the thickness
the temperature should be set anywhere between 370 to 500 °F (187 to
260 °C). If you are using a lead-free solder, increase above temperatures
by 40 to 70 °F (5 to 20 °C).
*ATTENTION* HIGHER TEMPERATURES WILL DAMAGE THE COMPONENTS ALONG
WITH THE CIRCUIT BOARD.
*ATTENTION*DO NOT TOUCH THE SOLDERING IRON WHEN IT IS HOT.
c) It is recommended that you clean the board with a fine brush, isopropyl
alcohol and lint-free cloth to get rid of any pre-existing residue, glue or dirt.
This way the solder will create a better joint with the copper surface.
d) Have your flush cutter, needle nose plier or tweezers handy.
e) Having a roll of paper tape helps you to keep the components in place
when soldering on the bottom side of the board.
f) Have a rosin flux pen or paste handy. Adding flux to the pads before
soldering the components makes the wetting process easier by letting the
melted solder to flow better on the pad and create a better joint.
*ATTENTION* SOLDERING SHOULD BE DONE IN A VENTILATED AREA. BREATHING SOLDER
FUMES WILL HARM YOU.
g) Always cut the excess leads with a flush cutter once a component is
soldered on the PCB. At least 1mm of the lead should stick out from the
solder joints.

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To begin the assembly
process, insert the resistors
as shown in the photo.
Pay attention to the color
coding of the resistors as
indicated in the “Bill of
Materials” section on page 3.
All soldering will be done on
the backside of the board.
You may proceed to solder the
ceramic capacitors and the
LEDs in place by following the
labelling on the board.
It is recommended to solder and cut of the excess leads with a flush cutter,
one component at a time. Save the excess leads from the LED that you have
cut-off, you will need them.

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Insert the transistor, the
potentiometer and the IC as
shown in the picture. Ensure
the transistor’s flat side
matches the outline of the
silkscreen. Ensure the notch of
the IC aligns with the markings
on the board, also known as
the silkscreen.
Please pay attention to the labelling of the transistors as one is an SS9012 and
the other is SS9013. They both have different functions and must go in the
correct place for this circuit to work!
Insert the 4-pin header,
the piezo buzzer and the
MQ sensor onto the board
and solder them as shown
in the image. Ensure that
the buzzer’s positive lead
(+) is facing down.
It is recommended to
solder the MQ2 element
with the label facing
inwards towards the
resistors.

8
On the provided sound
chip card, solder the
remaining resistor (R11)
in the kit on the two
through-hole pads as
shown.
This secondary PCB has an integrated sound
chip that controls the buzzer when it goes off.
You have two options to solder this
component.
Option 1: As shown in the photo, solder the
secondary board on the backside of the
board. To install in the correct orientation,
use the MQ2 solder point as reference.
Option
2: As shown in the photo, solder the
secondary board on the top side using
the left over LED or resistor leads that you
set aside from the previous steps. You
will require a vice to help keep the
components in place while soldering.

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Implementation:
You have three methods you can use this module. The first method is to use this
device as a standalone module where, when gas is detected in the MQ2 the
buzzer will make a noise and D1 will light up to inform you that Methane, Butane
or LPG has been detected. You may use the potentiometer R3 to adjust the
sensitivity of the detector.
Note: Do not expose the sensor to open flame!
The second method to use this module is to connect the third pin to Arduino
analog pin and use analog read sketch to read the values from this module.
This example code can be found in the Arduino IDE under
File>Examples>Basics>AnalogReadSerial.
The third method to use this module is to connect the fourth pin to Arduino
digital pin and use digital read sketch to read when the sensor is active high or
active low.
This example code can be found in the Arduino IDE under
File>Examples>Basics>DigitalReadSerial.