This is Insects and mouse repellent circuit using IC556, use high frequency
out of the piezo speaker and IC-556 is base as oscillator between 22kHz and
This projects is safer and more convenient than using chemicals to turn switch on only and use Low power consumption (only 0.5 watt) .
How This Circuit works
The working of this circuit is easy because IC1 is IC556 that has working principle resemble with IC555 there. So, the IC-556 have dual oscillator generators within an one IC, but IC555 has single oscillator only.
The reason that we must use dual oscillator generators because the first section will bring to control voltage at pin 11 , which this voltage will control the IC changes from 22 Khz to 56KHz ,and this voltage has value is 1/3 to 2/3 of power supply.
When voltage change cause frequency also change. And this frequency is changed all time because mouse, rat, bug,insects and various animal have ability to a different frequency response. When frequency is changed in range 22KHZ to 56KHZ, makes we can repel a lot of the type of animals.
The IC1/1 will produce a base frequency by include C1, R1 and R2. Which there are frequencies to controls voltage at pin 11. And then the IC1/2 also serves as produce frequencies as same as it, that include C2, R4 and R5 but there are higher frequencies than IC1/1.
When pin 11 voltage changed since IC1/1 causes frequencies at IC1/2 now produce so changing from 22kHz and 56kHz there. The output will be connected to a piezo speaker which is the special speaker that responsible just higher frequencies only.
How to build this projects.
First search all parts before such as PCB, resistors, capacitors, etc. when finished ,then make the as same real PCB layout as Figure 2. Next, to assemble all components as Figure 3.
Which Should solder lower parts before such as resistors,capacitors, piezo, and others parts in sequence. And do not remember all wires to circuit.
The Soldering, should the soldering iron be used size under 30 watts, and should use a lead combination of 60/40, and Should be careful the heat from the soldering iron to the IC directly. Or should use a socket IC.
The piezo speaker is the specialty type speaker. Which high frequency response than plain speakers. If apply with plain speaker will be not get in frequencies as we want, because it responsible frequencies that That the human ear can only hear.
How to testing
When we assemble this projects as finished, then enter the power supply to positive supply and ground. The frequency generator will out of the piezo speaker. Which we can not hear sound, but when place your index finger touch at pin 8 of IC, then remove the piezoelectric and replace with the plain speaker, cause sound out of the speaker indicate this projects works so well.
How to use it.
Just only you put this projects at a corner or nook in your home kitchen, or use outside the home. To turn into a switch. Next, we have no rats or cockroaches disturbed for a long time. Until battery power is exhausted.
The components list.
Resistors ¼ W + 5%
Mylar capacitors 50V
D1覧覧覧-1N4001 50V 1A Diode
IC1覧覧覧IC556 dual timer IC with socket DIP 8pin.
And others parts.
Battery 9V,LED, Piezo speaker, etc.