Showing posts with label how to make. Show all posts
Showing posts with label how to make. Show all posts

Saturday, 16 January 2016

Electronic mosquito repelent ultrasonic frequency generator circuit

Dear friends today we are going to learn how to make a circuit which act as mosquito repellent.

This circuit is very much easy to understand and use. A circuit with minimum components repel mosquito. Large number of things like coils, creams, oils is available in the market to repel mosquito. But these replant is also harmful for the humans . Oils and creams can led to skin disease, while coils or mats produces toxic fumes which can lead to breathing problem and lung cancer.

Our circuit do no harm for human being as it produces frequency which human being can not hear. Mosquito repellent generates a frequency ranges from 20-38 KHz. And mosquito runs away from your house as they irritates from these range of frequency.
Humans are only able to hear frequency which has a range from 20Hz to 20 KHz. All the rest frequency above this is considered as a ultrasonic frequency. Many animals and insects are able to hear this range of frequency. Usually in mosquitoes ultra sound is generated by the males and female one receives that one. While after breeding female mosquito usually used to avoid this frequency. And this circuit produces the same frequency as the male one generates, and these creates a stress on the antennae of the mosquito and these keep them away.
Here the 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 IC which is linked as a astablemultivibrator.

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 timer IC 555 which is out pin of IC 38 KHz frequency drives to 38 kHz piexo buzzer. This buzzer will produce a ultrasound at a regular interval.
By altering the value of resistor R2 we can alter the output frequency.
By changing the value of resistor and capacitor, it can also use as an insect replier as insects are also able to hear ultrasound.
From the source ultrasound are transportable only at 45 degree. So in the situation when there is any hurdles in the track signals get diverted. Also it works on the place where population of mosquito are not much more.

Component Description:-

1. Power supply (12V)

2. Resistors (2.7kΩ x 2)

3. Capacitors (0.01µF x 2)

4. NE 555 timer

5. IC Diode (1N4007)

6. Piezo Buzzer

Working principle:-

(1) Here the 555 timer is configured in astable multivibrator mode , specifically devised for generating sound at the ultra frequency levels.

(2) The frequency of this circuit is set to 25 kHz, this frequency falls in the ultrasound region and it is not audible to human beings.
The 1N4007 diode is used to get 50% duty cycle for the frequency generator.

(3) The piezo buzzer converts the output of 555 astable to ultrasonic sound that can be heard by the insects.

(4) This ultrasound frequency cause some irritations and uneasiness to the insects such as mosquitoes. However it will not disturb you if you have installed this circuit of insect repellent for your home.

How to design this circuit:-

We need 25 kHz signal, so the time period will be 40µseconds .
Then T =T =20µSeconds .
use R= 2.7kΩ standard.

Saturday, 22 March 2014

How to make Transformerless or Electronic Power Supply/Driver

How to Make Transformerless 12Volt 1 Ampere or 2 ampere or more amperage compact DC electronic Power Supply or Driver/Charger.


Today we are going to learn how to design and make the Cheapest and Smallest Transformerless electronic Power Supply or capacitive power supply 12v 1a or 2a according to our requirement. Actually there are many Power supplies available in the market but most of them are transformer/smps based and are very Big, Bulky, ugly, costly and have very complex circuitary to understand by a complete newbie.

So, lets get started to learn the design procedure so that we will be able to make the desired electronic power supply onward.

The biggest advantage of this explained circuit is that it is independent of input voltages fluctuations to a great extent

Here, we assume the input power source used here is 220V AC OR 110V AC 50~60Hz from home wall socket directly.


C1= 400V, 1395K Capacitor or (Connect three 400v, 475k caramic capacitor in parallel or three 2uf/400v caramic capacitor) (Note if the mains current is 220v AC 50-60Hz if mains is 110v AC then use 250v/1395k).

[The above circuit is Verified and Tested circuit by me and works great, so make it, save money & enjoy.]


In above circuit, R1 is actually doing nothing, but serve's the purpose of Bleeder Resistance, means it discharges the Charge stored in C1 gradually when the circuit is not in use( it may takes time between 1 to 15 sec according to its value and amount of charge stored).

This power supply is best suited for Capacitive loads like charging the battery, LED Drivers or any capacitive load...

So, By by reading the below post you guys will be able to design and make the power supply of any current rating and voltage rating according to your requirement. So please be focused and attentive to understand the technical specifications.

[Instruction: Above project deals with mains AC current & not isolated from AC mains, So be careful and work always under the guidance of any elder if you are a complete newbie. Please always remember to keep your one hand in pocket whenever working with any live circuit so that in case the current wont pass through your heart just for safety].


In my next post i m going to post a circuit of 12V 5 ampere transformer less electronic switch mode power supply(or SMPS based) or Driver.

Posts Recommended:

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  6. Make 5V 1Amp Cell Phone battery Charger Circuit from 220/110v
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Today we are going learn a new type of circuit generally known RC circuit or capacitive power supply, which is the simplest and Cheapest circuit you will find ever.

I have created this Circuit during my research on how to increasing the power output of electronic or transformer less power supply for capacitive loads.

So now the question arises here is that - How to make this great and easy piece of Transformerless Electronic Power Supply or LED driver circuit at home.

C1= 400V, 1395K Capacitor or (Connect three 400v/475k or two 2uF/400V capacitor in parallel for 1.2Ampere or higher capacitance for higher current according to the calculations explained below).

R1= 10M ohm or 1M ohm 1watt resistor.

D1-D4= IN5408 (4 DIODES)( just choose diodes which have double ratig for our curent requirement for e.g. for 2 amp choose diode of rating 4 amp...)

R2= 10 ohm 1 or 2 watt.( 2 watt will be better for heat handling or dissipation)

C2= 1000uF(micro faraday) ,50 v ( 2 in number if you finds the output is fluctuating, connect them in parallel for better filtering of ripples produced due to rectification of AC mains current).

z1= zener of 15v to prevent any voltage fluctuations caused due to input voltage fluctuation to regulate our DC output to maximum of 15 volt max in extreme case.

{note: you must add a 10M or 1M ohm as a bleeder resistance parallel to C2 for Discharging the charge stored in C2 otherwise you may get a high current shock or surge current dur to charge stored in the capacitor if this charge is not discharged when circuit is not in operation it is going to remain for very long time and someone may get the shock. In later posts we will learn the techenique to remove any surge current by incorporating a crowbar circuit at the output. So simply to understand better this circuit and make it simple simply connect a higher value capacitor across capacitor C1.}

{Do not touch any terminals with bare hands even the Driver is Unplugged. First discharge the C1 and C2 by shorting the input and output terminal together. there will be spark generated while doing this this means charge stored is discharged completely by you now. Only after that you should touch any terminal, or leave for some time before touching the terminals so that bleeder resistance work for you to discharge the charge stored in capacitor C1.}


If we use 2uF/400V(because it is readily available in the market) THEN :

the capacitive reactance offered by capacitor(2uF/400V) connected at mains supply is:
x= 1/(2*pi*f*c) where pi is 22/7, and f is the frequency of mains supply eg 50Hz or 60Hz
now reactance or impidence ( or simply resistance) of whole ckt is = sqrt(R+x) where R is the resistance or load and wires all together attached in circuit and sqrt means squareroot of (R+X)
now out put current i=(v/z) where v= mains voltage 220v or 111v
So you can now calculate the capacitance of circuit according to the required current.

If you want to increase the output current just simply increases the capacitance value of C1 or just by Adding more C1 together in parallel if you are unable to find the appropriate value capacitor in market.

The C2 here only used as a filter to reduce the ripples in the output waveform.( it acts as filter to smoothen the output DC desired.)

Z1 is zener to protect the appliances from overvoltages.

If you want to decrease the voltage rating just use appropriate zener diode

If you wanted to increase the voltage rating of the circuit to double just use doubler circuit to double the voltage but the catch is that the current will become half and frequency become twice means 120Hz. so according to your requirement just increase the output DC current by simply adding high capacitance capacitor or add more C1 in parallel if you need high output DC voltage

For capacitance C1 related calculation problems or any problem regarding this explained circuit please reply in comment section and i will be happy to help by reply ASAP.

If you find above circuit interesting or useful please share it will be our reward from your side.

 Thank you for Reading.