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Alcohol Tester Kit MQ-3 Detection Sensor Module Welding Training DIY parts
Brand GreenZech
New
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Delivery: Standard (Free) | Mon 26th - Wed 28th Oct
Sold by: GreenZech
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Description & Details
Alcohol Tester Kit MQ-3 Detection Sensor Module Welding Training DIY parts Description
Feature:
When
alcohol
vapor
exists
in
the
environment
where
the
sensor
MQ-3
is
located,
the
conductivity
of
the
sensor
will
increase
as
the
alcohol
vapor
concentration
increases.
By
measuring
the
series
partial
pressure
between
the
sensor
and
the
fixed
resistor,
the
alcohol
content
in
the
environment
can
be
determined.
Working
voltage:
5-7.5V
DC.
PCB
size:
6.2*3.6cm.
Circuit
description:
This
circuit
can
be
powered
by
a
5-7.5
volt
DC
power
supply.
The
switch
S1
is
a
power
switch.
The
resistor
R1
and
the
light-emitting
diode
D1
are
used
for
power
indication.
The
sensor
MQ-3
needs
to
be
heated
to
a
certain
temperature
during
operation,
so
there
is
a
section
of
electric
heating
installed
inside
it
The
wire
and
resistor
R4
are
the
current-limiting
resistance
of
the
heating
wire.
It
is
normal
for
the
MQ-3
to
generate
heat
after
being
energized.
When
MQ-3
does
not
detect
alcohol
vapor,
its
internal
resistance
is
very
large,
the
voltage
drop
of
R3
and
RW
is
very
low,
the
voltage
of
pin
2
of
NE555
is
lower
than
the
trigger
voltage
(VCC/3),
its
pin
3
outputs
high
level,
D2
goes
out
,
The
buzzer
does
not
sound,
and
the
relay
does
not
operate.
When
MQ-3
detects
alcohol
vapor,
the
internal
resistance
drops,
the
voltage
of
R3
and
RW
rises,
the
voltage
of
pin
2
of
NE555
is
higher
than
the
trigger
voltage,
pin
3
becomes
low
level,
D2
turns
on
and
emits
light,
and
the
buzzer
flows
The
current
starts
to
sound,
and
the
electromagnetic
coil
in
the
relay
is
energized
to
attract
the
switching
action.
In
order
to
realize
the
detection
and
alarm
function.
Adjustable
resistor
RW
is
used
to
adjust
the
detection
sensitivity.
This
circuit
uses
the
second
comparator
inside
NE555
to
detect
the
voltage
change
and
uses
its
internal
trigger
to
debounce.
Pin
7
and
pin
5
of
NE555
are
not
used
and
are
in
a
floating
state.
The
output
terminal
J3
of
the
relay
can
be
used
to
control
other
electrical
appliances,
such
as
an
exhaust
fan.
When
the
alcohol
concentration
exceeds
the
standard,
the
exhaust
fan
is
started.
After
the
concentration
drops,
the
exhaust
fan
is
turned
off
to
realize
automatic
control.
The
diode
D3
is
used
to
eliminate
the
induced
electromotive
force
generated
when
the
relay
coil
is
turned
on
and
off.
The
power
supply
interface
can
be
a
DC
plug,
or
you
can
use
a
wire
directly
at
the
J2
position,
pay
attention
to
the
positive
and
negative
signs,
the
DC
plug
power
supply
is
positive
and
negative.
Package
includes:
1
x
DIY
KIT.
Details
| OPC | PGKD69S |
|---|---|
| Brand | GreenZech |
| Codes | 8727971252734 (EAN) |
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