Simple Tranformerless Power supply


It is very easy to convert 220 Volt AC to DC for powering electronic circuits. Any DC voltage from 3 volt to 36 volt can be generated from 220 volt AC using appropriate value of X rated capacitor and Zener diodes. The X rated capacitor drops 220 V AC to low volt AC. This can be rectified to DC by a Rectifier diode and smoothed by a Filter capacitor. By selecting a required value Zener, regulated DC can be obtained. But the only drawback of the Tranformerless power supply is its low current, so only light loads can be used. Here explains the design of a 4.7 Volt 4.6 Milli Ampere Tranformerless power supply to power PIR sensor .

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AC Powered PIR Light


A Simple design of PIR Light using Tranformerless Power Supply and Triac for driving the load. Too compact and can be enclosed in a small case. The light turns on when the PIR sensor detects human movement and turns off after the preset time. Re triggers in another movement. Its range is 30 cm to 10 meters and time delay, 30 seconds to 3 minutes both can be adjusted using the presets in the PIR sensor Module.

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Fast Charger for Car battery



Here is an efficient Car battery charger for fast charging the Car battery. It is a 5 Ampere charger with Digital Volt and Ampere Meter to display the charging voltage and current. Since the charger provides maximum 5 Amps current, battery can take high current it needs to charge very fast. As the charging process completes, current flow reduces to zero and will be displayed in the meter. So it is easy to confirm whether the battery is fully charged or not.
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How to connect Panel Meter in Battery Charger



Digital Volt Ampere Meters are now available which can be used in Battery chargers to monitor voltage and current. One section of the Meter displays 0 to 100 V DC and the second section displays current 0 to 10 Amperes. The Meter works off 4 to 30 V DC. Let us see how it can be used in a charger….
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Automatic Car Battery Charger


This 5 Amps charger automatically stops charging when the terminal voltage of battery rises to 13.7 V thus preventing over charging. If the battery voltage drops below 11 V, Charger turns on and starts charging. Check it……….
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Wireless Electricity Generator


Wireless Electricity Generator
Here is a High Efficiency Wireless Electricity Generator project. Usually we make a simple wireless electricity generator to light 1.8 volt Red LED. But here the efficiency of the Wireless Electricity Generator is increased to light 1 Watt White LED Bulb that requires 3.6V. It generates voltage and current even to light a Strip LED. Try it and see the wonder of LED lighting without a battery connection.

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PIR Sensor Alarm


PIR Sensor Alarm

This simple alarm can be used to detect the movement of human beings at a distance of 10 meters. It works both day and night and beeps shortly when there is a human movement through its detecting range. It is ideal to monitor the entry passages, stair case, corridors etc. It is highly useful to monitor the human movements in Flats, Multi storied buildings, Shops etc. A relay can also be connected for activating lights, electric alarms etc. It can be used as a Personal alarm during journey to protect luggage.
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How to connect Digital Volt Ampere Meter


How  to connect Digital Volt Ampere Meter
Digital Volt Ampere meters are now available to measure DC voltage and Current. It can be connected to the output of the Power supply. So the output voltage and current to the load is displayed in the meter. If a battery is connected to the power supply for charging, we can see the current consuming by the battery during charging. When the battery is fully charged, current drops to zero which indicates the termination of charging. If project is connected, the voltage and current to the project is displayed.
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Ultrasonic Pest Chaser


Ultrasonic Pest Chaser

Here is an efficient Electronic Pest Repellent to chase Pests from home. It emits Ultrasound in the frequency 9 to 96 kHz which can be set for each Pest. Human can’t here the Ultrasound since it is out of human sound detection range. But most animals can hear Ultrasound.The circuit emits powerful Ultrasound to repel pests.

Mosquitoes are usually repelled between 20 and 40 kHz, Rats around 56 kHz, Cockroaches around 36 kHz and Flies around 30 kHz. Out put power of the circuit is 2 watts 1.3 dB. It can repel Mosquitoes, Rats, Cockroaches, Wall Lizards , House flies etc from home. Made and found effective.


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Power regulation using IC


Voltage regulation through Fixed Voltage Regulator IC is the most suitable method.78xx series positive and negative regulators are widely used to get fixed voltage to drive loads. Here explains a circuit design to get regulated voltage from a 12 volt 500 mA power supply .This circuit can deliver 5 volts at 300 mA for driving a load.

The circuit is Voltage and Current regulated and with Polarity and Surge protection components.
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How to select resistor for 1 watt LED


1 Watt LEDs are widely used in Emergency lights and LED lights. Most of the circuits use 4 volt battery having 0.5 to 4 Ah capacity. The 1 watt LED is rated 3.6 volts maximum so we need the correct value resistor for LED to get maximum brightness. Let us see how the LED resistor value is determined.
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Solar Garden Light


Solar Garden Light
Make a lighting path in the garden using this simple Solar LED light. It automatically turns on in the evening and gives light in the garden. LED light turns off in the morning. You can select any colour LED like Green, White or Yellow as per the choice.
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Automatic Solar Outdoor Light


Automatic Solar Outdoor Light

Very simple to construct an Automatic Garden light using Solar Panel and LED light. ON in the evening and OFF in the morning. No switching needed and it light the premises of home even if inmates are not there. No circuit complication is here instead  only a Relay and few components are used to make this efficient Solar light. It is very well lighting my home.

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Efficient Car Battery Charger


It charges 12 V Lead Acid battery with 5 Amps current and Automatically stops charging when the battery voltage increases above 13.8 V to prevent over charging. Charger starts charging when the battery voltage is below 11.8 V and stops charging at 13.8 V.
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Automatic Battery Charger


Here is an efficient battery charger for Car battery and Inverter battery. It quick charges the battery with 5 Ampere current and cut off charging when the battery attains 13.8 V which is the full charge condition of the Lead Acid battery. Red LED indicates charging process while Green LED indicates full charge and charger cut off status.
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How to determine the current in X rated capacitors


High volt X rated capacitors are used to make Transformerless power supply. But the current delivering capacity of such power supply is very low generally less than 100 mA. Let us see how to select a Capacitor to get required current
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How to make a Mini Power Bank


Don’t throw away the old Mobile battery. The high efficiency Lithium Ion battery can be reused to make a Mini Power bank useful as a Travel Mobile charger. For this, you needs a Lithium battery charger Module and a Mobile charger module in addition to the battery. Both modules will cost around Rs.100.
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How to connect Relay with NPN and PNP transistors


Transistor is used to drive relay to connect AC loads. For efficient working, it is important to connect the relay correctly in NPN and PNP transistors. See the way of connection. Continue reading

How to connect 7 segment display in circuits


7 segment display is used in Counter circuits, Temperature sensing circuits, Timers, Clock circuits etc. Let us see its pins and way of connection Continue reading

How to set CD 4060 IC as Timer


CD 4060 is the versatile Binary counter IC that can be used in Timer applications.When a resistor is connected to its pin 10 and a capacitor in its pin 9, it forms an oscillator that gives pulses to its pin 11.According to the timing cycle, each output goes high one by one. Output gives around 10 mA current and a voltage near to the supply voltage. Timer oscillates only when its Reset pin 12 is grounded. Continue reading

How to determine the voltage level in Lithium Ion battery


Lithium Ion batteries are now widely used in Mobile phones, Power banks, Digital cameras and other devices that requires 3.6 V . Lithium Ion batteries are long lasting since its current rating is very high above 2300 mAh.It is very important to maintain Lithium Ion batteries since, both over charging and poor charging may completely destroy the battery.Some have the habit of plugging the Mobile phone in charger overnight. Mobile battery needs to be charged only when its charge goes below 50 %.Proper charging and discharging increases the life of Mobile battery and its efficiency. Let us see its voltage levels
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How to fix PIR sensor Alarm


PIR sensor is the ideal device to use as Surveillance systems that operates by sensing human body heat. It triggers the alarm from a distance of 10 meters when a human passes. It operates both day and night. Let us see how to fix it on the wall
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How to set the Re trigger Jumper in PIR sensor Module


The PIR sensor module has a Jumper arrangement to select single trigger and re trigger modes. Let us see how it works Continue reading

How to connect PIR sensor Module


It is important to know the connections of PIR sensor module. It is easy to connect it with alarms, relay to drive AC load etc. Let us see Continue reading

How PIR Sensor works


PIR sensor module is an ideal device to make efficient alarm systems and save energy lights. Let us see how it works?

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How to make a simple Transformerless Power supply


Most simple Transformerless power supply that can convert 220 V AC to DC. Out put DC depends on the value of the Zener used. Output current is 60-80 mA.
See the step wise procedure

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How to Convert SMPS to Bench Power supply cum charger



Don’t throw away the SMPS power supply when the Computer damges. SMPS is a high current device that gives different regulated voltages from the output wires. It has numerous wires to give different voltages . So you can make a good Multi voltage power supply for the Projects or use as battery charger for different types of batteries. It has total isolation from Mains and output is safe DC.
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Power Supply Box


This Power supply box can be used to interface with the High current Bench power supply made from the SMPS of Computer. The Power supply box has a DC-DC Converter cum Booster module, A Volt Meter and an Ammeter to show output voltage and current consumed by the load. Continue reading

How to retrieve data from the Laptop Hard Disk


Suppose the Laptop crashes and is irrecoverably damaged .Its Hard disk has full of valuable data. What will do to recover that? SATA to USB device will help. Its cost is just Rs.170 and available in Computer sellers. Open the small window on the back of laptop. You can see the Hard Disk there. Unplug from its socket. Connect it to the SATA-USB socket. Connect the USB cable to PC or Laptop. It will detect the removed Hard Disk. You can open the folders and copy the data. It can be a good external hard disk in future. Continue reading

How to retrieve data from a Hard disk.


Suppose the computer mother board crashes and the PC is irrecoverably damaged .Its Hard disk has full of valuable data. What will do to recover that? SATA to USB device will help. Just plug in its power supply and data cables to the Hard disk removed from the PC. Connect the USB cable of SATA- USB unit to a computer or laptop. The PC will detect the hard disk and you can copy the files to the computer. You can also use this Hard disk as an external hard disk.

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How to convert SMPS Power Supply to Bench Power supply


Don’t throw away the SMPS power supply when the Computer fails. It is a high current device that gives different regulated voltages from the output wires. It has numerous wires to give different voltages . So you can make a good Multi voltage power supply for the Projects or use as battery charger for different types of batteries. It has total isolation from Mains and output is safe DC.
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Simple LED Volt Meter


A simple LED Volt Meter using Zener diodes as switches. If it is connected to a 12 Volt battery it shows the following indications.

 

Flash LED Blinks – Above 13 volt – Fully charged
Green LED lights – Above 11.8 V
Yellow LED lights – Above 11.5 V
Red LED lights – Above 10.6 V

If all LEDs light, battery voltage is above 13 volt and fully charged

DC-DC Converter Module. Application Circuit 6


dc-dc-converter-8
This is an excellent DC- DC Converter Module that can adjust the output voltage to any desired value, even fractions from 0 V to 17 V. It is a very good Variable Power supply Module. But pressing the switch we can adjust the output voltage. It can handle a Peak current of 3 Amps. The output voltage and current are displayed in an LCD Screen that has back light. If the input voltage is from a Battery, the LCD display shows the Battery Level also.  Input voltage can be between 5V and 23 V but the best voltage is 20 V. It has 95% conversion efficiency and 1% LCD accuracy. It is available with a transparent casing. You can fix it in the case provided along with the Module.It can be connected to the Bread board so that we can determine the current consumed by the project.  Its cost is just Rs.350.
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IR Sensor Tester. Application Circuit 5


ir-sensor-tester-1Here is a simple tester to test the IR Sensor TSOP 1738. It is a highly sensitive device that damage easily if its input voltage rises above 5V. This Tester can be used to test TSOP 1738 before using in a circuit. It confirms the condition of the Sensor, whether it is functioning properly or not. It can also be used to check the IR Sensors kept in your junk box so that you can keep only the good one for use.

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IR Transmitter Tester. Application Circuit 4


ir-transmitter-circuitWe make Infrared Transmitter circuits to generate Pulsed Infrared rays to use with IR Sensor based receivers. The IR Transmitter circuit based on IC 555 generates IR rays pulsating in the frequency typically at 38KHz. The IR Sensor used in the receiver is TSOP 1738 which also works in the same frequency. So here is a simple IR Transmitter Tester to check whether the IR Transmitter is emitting 38 KHz frequency or not.
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Hacking a Remote. Application Circuit 3


remote-5We construct different types of Infrared Receiver LED ( Rx) or IR Sensor ( TSOP 1738 ) based circuits. To test, the working of the circuit we have to use an IR Transmitter. Usually we use IC 555 based IR transmitter for this. But the frequency of the IR from the Transmitter should match with that of the Sensor, otherwise the circuit will not respond. Here is a simple solution to test the IR based circuits. Simply Hack a Mini Remote obtained along with low cost FM radio, Toys etc. You have such Remotes in your Junk box. Let us Hack one such Remote to make a Tester.
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IR LED Tester. Application Circuit 2


led-testerIR Rays are invisible to human eye, so it is very difficult to check the working of IR LED. Usually we use a Mobile camera to test IR LED since the pink light from the IR LED becomes visible in digital camera. We can make a simple IR LED tester so that, before using it in the project, we can confirm whether it is good or not. Lot of IR LEDs are also in our Junk box. So we can check all IR LEDs and  discard the damaged ones. The same tester can be used to check all ordinary LEDs, Photo diodes, Silicon and Germanium diodes etc.

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Deterrent Light. Application Circuit 1


deterrent-light-circuit
Install this Deterrent Light in your Home backyard and Porch to thwart the attempt of Burglary. This PIR Motion Sensor based light switches on instantly when it detects a Human movement from a distance of ten meters. The light turns on for 3 minutes and then turns off. It Re triggers again if the movement continues. Relay is used to drive the load, so any kind of lights can be used.
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Car USB Charger using MC 34063. Start Up Project 40


usb-charger2So many types of Car USB chargers are available which step down the 12 volt DC from the Car battery to 5V DC for charging devices like Mobile phone, Tablets, MP3 player etc. These are usually connected to the Lighter socket to get 12V. The low cost chargers do not have a circuit inside but simply providing 12V DC directly. Only a fuse is present in it. This is dangerous because, the Car battery is a high current one which can damage the gadgets. Here is a simple solution for this. We can make a Voltage and Current regulated Car Charger using the IC MC 34063. It is a Step down DC – DC Converter IC with many features. The output from the circuit will be 5 V at 500 mA.

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LED Indicator for Emergency Lamp. Start Up Project 39


charge-indicator-2-aMost of the low cost LED Emergency lamps do not have LED indicators to show charging and load on conditions. This simple circuit solves the problem. It can be hooked in the Emergency lamp. A Green LED lights when the charging is going on and turns off when the charger is disconnected or power fails. It gives a good indication that current is flowing to the battery. A Red LED lights when the load turns on. It also indicates that charging process stopped.
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Laptop Battery Power supply. Start Up Project 38


12ADon’t throw away old Laptop battery; it can be reused for other purposes. I hacked one Laptop battery and salvaged six high efficient Samsung Lithium Ion batteries each rated 3.6V, 4300 mAh. It is worth Rs. 1000. Few days before, I found that, my Laptop is not getting enough back up and shutdown immediately when the charger is removed. So I replaced the battery at the cost of Rs.1200. Due to curiosity, I just opened the case of the old battery pack and found that, the batteries inside can be reused. After testing, I found that only one battery out of the six is damaged. All the other five are in good condition. That damaged battery created the problem in the battery pack and prevented the remaining five batteries from their work. So actually this is happening in our Laptop. If one battery fails, we have to replace the battery pack. If the good batteries are salvaged from the old pack, we can reuse them for many different applications like LED lighting, Mobile charging, making power supply etc. So I spend Rs.1200 for the new battery pack but I salvaged 5 good batteries worth Rs. 1000 from the old battery pack. So my actual expense is only Rs.200. So do not discard the old Laptop battery. Tear it, salvage the individual batteries and reuse. You can save money and can reduce the e-waste.
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Peltier Joule Thief. Start Up Project 37


13AYou know, we can light a 1 watt LED without a battery! Peltier will give “Free Electricity” for that. When we heat the Peltier with flame, hot water or a hot object, it starts to generate current. Its voltage can be around 1.5V when the heat is above 60 degree. But this 1.5V is not sufficient to light even an ordinary LED that requires 1.8V minimum. 1 watt White LED requires 3.6V. Then how? We can add a Joule Thief circuit for that. A Joule Thief circuit is a self oscillating circuit that increases the input voltage as low as 700 mV to 4-5V. So if the Peltier is connected to a Joule Thief and heated, Joule thief will amplify the voltage to light the 1 watt LED. Let us check this.
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Peltier Electricity. Start Up Project 36


12APeltier is the Fantastic device used to make cooling devices. When a current of more than 500 mA passes through the Peltier, its one side cools while the other side turns hot. This is due to the transfer of heat from one side of the Peltier semiconductor to the other. As the current increases above 1 Amps , the cooling effect increases and the temperature of the cold side of Peltier drops below 0 degree. But if we reverse the function of Peltier, it generates electricity. For example, if we heat one side of Peltier above 60 degree using a hot object, hot water or flame, Peltier generates around 1.6V DC and around 350mA current. Let us make one circuit of “Free energy “generation using a Peltier Module. Since the 1.5V from the Peltier is not sufficient for lighting an LED, we have to add a voltage booster to increase the Peltier voltage sufficient to light the LED. If 5 Peltier are serially connected, we can even charge our Mobile phone using a Candle flame.

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Mobile Scanner. Start Up Project 35


2AKeep this Match box size Mobile Scanner in your pocket. It will Scan around you and beeps loudly when a Mobile phone turns active in your vicinity. It can detect the activation of Mobile phone around 2 Meters radius. It beeps during incoming call, outgoing call and when somebody tries to take your Photo. It is an ideal device to detect Mobile phone use in examinations halls, confidential rooms, hospitals etc where Mobile phone is strictly prohibited. Its range can be from 50 cm to 3 meters depending on the type of the active Mobile phone. With  Smart phones, its range is less than 1 meter because there is a mechanism in it to prevent excess radiation. But in ordinary Mobile phones, its range can be up to three meters. Try this nice weekend project.
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USB Wall Socket. Start Up Project 34


15AI have many devices using USB Port for charging. For this, I purchased one USB Hub to connect 4 devices at a time. But the result was disappointing . The devices are not charging and even a Pen drive is not opening in the Hub. Analyzed the reason and found that the USB port of Laptop is not giving sufficient current to the devices for charging. The USB.2.0 Port can give maximum 200 mA current and USB.3.0 can give maximum 400 mA current. Then how all these 4 devices in the Hub charge normally. The 200 mA current from the Laptop port is sharing to all devices, so no one is charging. Moreover, the Laptop gave a warning that, “USB Port over loaded and shutting down”. Remembered that famous saying “Every problem born with its own solution”. Got the remedy. If the current to the USB Hub is increased, all devices will charge normally. But in that case, Laptop is not useful and I have to make a separate power supply. So made a USB Wall socket. It has an AC socket for charging Laptop, and a 5V, 1 Amps SMPS power supply to power the USB hub. Thus the problem solved. The USB Wall socket is fixed on the wall and powered from Mains. SMPS has well AC-DC isolation, so no shock hazard while charging the USB devices. I found the same type of USB Wall socket in the Online shop but its cost is Rs.2500. I made it at the cost of Rs.250. Let us check it.
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