Basic principal of
this circuit is to connect a such type of buzzer which can produce ultrasonic
frequency range. With the help of oscillator in the circuit, buzzer is driven.
And in the circuit oscillation is generated by 555 timer which is linked as a
astable multivibrator.
The circuit is
connected in the closed mode and thus power is received by the 555 timer. In
the starting stage voltage in the capacitor is zero volts. So the voltage at
the threshold `as well trigger pin is at zero volts. Now the capacitor starts
charging via a resistor R1 and R2.There will be one point when the voltage of
capacitor will be higher as compared to threshold voltage. At this stage
capacitor starts discharging with the help of resistor R2, which is a
discharging pin and it keeps of going downward till it reaches to its original
state. Thus the signal at the output pin of IC will be an oscillating signal
having 38 KHz frequency. With the help of pin 3 of IC which is out pin of IC 38
KHz frequency drives to 38 KHzpiezo buzzer. This buzzer will produce a
ultrasound at a regular interval. By altering the value of resistor R2 we can
alter the output frequency.
Components Required
IC
(IC1)
NE555
Capacitor (C1, C2) 0.01uF
Resistor (R1 760E),( R2 1.5K)
PiezoBuzzer(B1)
38KHz
Fig 1 circuit Diagram
Fig 2 Circuit on
bread board
FAQs
Why use Electronic Mosquito Repellers ?
In addition to being
pesky bloodsuckers, mosquitoes are also carriers of various diseases, like dengue, malaria etc. These diseases can even
prove to be fatal for the
poor, who have little access to medical care.
Methods of repelling
mosquitoes have been around for a long time. Most of us are familiar with
mosquito repellent creams, wristbands, clothes and plug in devices. Out of
these, mosquito repellent wall plug vaporiser devices are the most effective.
However, they vaporize chemicals that are not only harmful to mosquitoes, but
to humans as well.
What is the relation between (US) Ultrasound
and animals?
Even though human ear
cannot sense US, many animals can produce and hear US. Many insects, rodents,
bats and small mammals communicate through US. Insects have sensory structures
to produce and detect ultrasound. Cockroaches have “Sensory hairs” to sense US.
Spiders, Wasps, Beetles, Flies etc have a “Tympanic membrane” to detect US.
Fleas communicate using high frequency US . Male Mosquitoes produce US to
attract females. Female mosquitoes have sensory structures to receive US.
Spiders, lizards also have ability to sense US.
How does US affect
animals?
The US sensors are
present in the antennae of Mosquitoes and genetalia of Cockroaches. US emitted
by the Repeller will scare away the pests and confuse them. Ultrasonic sound
will create stress on the nervous system of insects and jam their own US
frequency. This will immobilize the insects and they escape from the source of
US.
How does Ultrasound
repel Mosquitoes?
Male mosquito is the
natural enemy of female mosquito after breeding. Both male and female
mosquitoes use plant juice as food. But female mosquito requires human blood
protein for the maturation of their eggs. Male mosquitoes will not bite human
beings. On the first day of emergence, the female mosquito will not bite but
after mating with male it starts to bite human beings to get blood. Female mosquito
will not allow males to mate again and they avoid the presence of males.
Females detect the presence of males by sensing the US produced by the males.
If an US generator is used, it will imitate male mosquito by producing 38 kHz
US . This will repel Female mosquitoes. Moreover the US will create stress on
the US sensillae present on the antenna of female mosquitoes, so the move away
from the source of US .
Does the US pass through walls?
No. Ultrasound will
not pass through walls like the ordinary sound waves. When the US hits an
object,it bends and round the object and spreads.
Is it safe for human
beings?
US Pest Repellers are widely used in Homes, Gardens, Farm yards etc. to repel
various kinds of pests. Commercial US Pest Repellers are designed to emit US in
the frequency range 20 kHz to 100 kHz. US above 20 kHz is inaudible to man but
children can hear the US to a certain level up to 30 kHz. Many house hold
appliances like Telephone, Computer, Vacuum cleaner etc emit US, but we cannot
hear it because it is inaudible. US is considered as the safest method for
scanning pregnancy. US scanning is widely used in hospitals. Echocardiogram
also uses US to image the heart’s functions. As per the scientific information,
US will not cause any health problems.
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