circuit ultrasonic mosquito repeller. This series is based on the theory that insects such as mosquitoes can be rejected by using sound frequencies in the ultrasonic (above 20KHz) range.
Circuit is only a CMOS 4047 PLL IC cable as working at 22KHz oscillator. A complementary symmetry amplifier consisting of four transistors are used to amplify sound. Piezo buzzer speaker amplifier to convert the output of the ultrasonic sound that can be heard by the insects.
IC CD4047B Description
CD4047B ICs capable of operating either in monostable or astable mode. It requires an external capacitor (between pins 1 and 3) and an external resistor (between pins 2 and 3) to determine the output pulse width in the monostable mode, and the frequency output in the astable mode. Astable operation is enabled with a high level in astable astable input or low level on the input. Output frequency (at 50% duty cycle) at an output Q and Q are determined by the time component. A double frequency Q is available at the Oscillator Output: a cycle of 50% is not guaranteed. Monostable operation is obtained when the device is triggered by low to high transition triggers at high b tolow input or trigger input transitions. This device can retriggered by applying simultaneous low to high transition both trigger and retrigger inputs. High level on Reset input resets the output to low to high.