Battery Chargers. Design Note 32


IMAGEPresenting here three circuits to make efficient Battery chargers. The 12 volt Lead Acid Car battery requires high current for fast charging. If we provide high current, the battery will charge within 1-2 hours fully. Usually a Lead Acid battery takes high current initially, which drops to 500 mA or less after 10-20 minutes. As a rule, it is advisable to charge the battery with a current that is 10 times lesser than the battery capacity. The Car battery is 32 Amps or 45 Amps so it requires 3.2 Ampere and 4.5 Ampere current respectively. So the charger should provide 14 volts with a current of 5 Amperes.

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Smart Solar Charger. Design Note 31


IMAGEYou can make a simple Current regulated Charger for your Solar Panel. It safely charges the 12 volt battery with a constant current of 540 Milli Amperes. It needs only a few components and can be hooked between the Solar panel and the battery. It also has an LED charge indicator and a revere polarity protection diode.
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RF Detector. Design Note 29


This is my latest Circuit published in the June 2015 issue of Electronics For You Magazine. It is a device that measures the intensity of Radiation in the room. Lot of Electromagnetic radiations are present in home emitting from WiFi, Mobile phone, Computer and other electronic devices. So the device shows the level of RF energy in a meter. Meter shows full deflection when the RF radiation is very high. It also gives a simultaneous LED indication.

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How to Protect Solar Inverter Battery .Design Note 28


Hybrid-Solar-Charger-Circui
One of the main problems in Solar Inverter system is poor charging of Battery during rainy seasons and in cloudy days. The high current Tubular battery requires more than 1 Ampere current for proper charging. To solve this problem, I have designed a” Hybrid Solar charger” and the circuit was published in Electronics for You magazine September 2013 issue. So the charger has two sides. One side gets power from Solar panel and the other side from a Step-down transformer. If the voltage from Solar panel reduces below 9 volts, the charger shifts to AC mode and battery charges via the current from transformer.
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Solar Power for Lighting. Design Note 27


Solar panelYou can use a Solar panel to power electrical appliances directly during day time if the Sunlight is very good, direct and continuous. So you have to install a Solar panel in a well lit area over the roof top in the East- West direction with a slight angle facing the Solar panel to the sky. So when the solar panel gets sunlight, it generates voltage and current which flows through the cables connected to it. You can have two options. The current can be stored in a battery to power the appliances at night through an Inverter or you can directly use the solar power using an Inverter without battery. Solar power is DC voltage and the Inverter converts this DC into AC to power the AC appliances. So let us see the requirements.
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Lightning Arrester. Design Note 26


GDT H 230 LB
Various kinds of Lightning arrester circuits are available, but here describes one with Multi-level protection so any one of the component may be damaged if a strong lightning occurs. Thus it leaves the gadget without damage. Usually one Surge protector like MOV, GDT, Bidirectional Diode etc is used in surge protector circuit. But here a combination of all the three is used to give multi level protection. The circuit can be hooked up in Telephones, Cable TV lines, Modem, Dish antenna cable etc.
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LCD TV Protector. Design Note 25


SIMAGEometimes you need a simple circuit to protect the Electronic gadgets like LCD TV from voltage fluctuations. Normal domestic power supply is 230 volts at 50Hz in most countries. But this voltage may not remain steady and may go as high as 250 volts or as low as 180 volts. Complaints in the distribution transformer, operation of heavy current appliances like flour mill, welding machine etc in the nearby places can cause severe voltage fluctuations in the lines. A good stabilizer with Buck / Boost facility can solve the problem, but still it is interesting to make this circuit and it costs less than Rs.100.It cut off the power supply to the gadget connected when the voltage increases above 230 volts and decreases below 200 volts.
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Understanding Symbols. Design Note 24


COMPONENTSAn Electronics Hobbyist needs to know the symbols of the electronic components in the Circuit diagram. Before starting the construction of a circuit, it is necessary to study the circuit diagram first. It has a number of symbols with the values marked. There are different symbols for representing the components. So it is necessary to study the symbols generally appearing in circuits.
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Understanding Capacitors. Design Note 23


TANTALUM As you know, Capacitors are inevitable parts of an electronic circuit, without which the circuit design is incomplete. Different types of capacitors are used in electronic circuits; each performs a function in the circuit. But basically, all the capacitors act as energy storing and transferring devices. Let us discuss the capacitor types, identification methods and functions.
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