Electronic Insect Repellent Circuit

Figure 1 

The circuit was designed to repel any form of insect using complimentary metal-oxide semiconductor or known as CMOS.

A basic mosquito repellent is an oscillator that produces repetitive electronic signals and generates ultra sounds (high frequency sounds). Other forms of insect repellents are applied to skin, clothing, and other surfaces that restrains insects from landing or climbing on that surface. These repellents are invented to prevent and control the epidemic of insect-borne disease such as malaria, lyme disease, dengue fever, bubonic plague and west nile fever.

A phase-locked loop used in the circuit refers to an electronic circuit with a voltage- or current-driven oscillator that maintains a constant phase angle relative to a reference signal. It encompasses the low-power monostable/astable multivibrator CMOS 4047 because of high noise immunity and low static power consumption. It acts as the oscillator having an effective frequency of 22 KHz. Amplification of th output si done by a pair of complementary transistors which means two transistors of opposite conductivity (PNP and NPN) in the same functional unit. It also utilizes Motorola 3.25 inch piezo for the purpose of producing high frequencies for destruction of insects. It has a rating of 28KHz. An external power supply would still be required to drive this circuit.

Source:www.zen22142.zen.co.uk/Circuits/Misc/insecrep.html