We all use LED bulbs today to save energy. Different types of LED bulbs ranging from 3 Watts to 15 Watts are now available at low cost. The LED bulb has an array of serially connected 0.5 watt Chip LEDs and a small capacitor power supply. We can also easily make the LED bulb. Let us see what is inside the LED bulb and the circuit operating it.
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Hum is a nuisance in Amplifier circuits which is mainly due to improper filtering of AC fraction from the power supply and improper grounding. Hum will reduce the quality of sound from the speaker. You can easily eliminate the hum from the amplifier to get clear voice.
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Presenting 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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Let us move to the world of capacitors. You can see a number of capacitors scattered here and there in the circuit board starting from the front end to the last. These capacitors are doing lot of job in the circuit like smoothing, filtering, coupling, de-coupling, buffering etc. You can also see the size and shape difference. The capacitors may be electrolytic or disc but the structure is identical in both having two electrodes separated by a dielectric material. But the functions will be different. For example, a Smoothing capacitor in the power supply section will remove ripples from AC to give a clean DC while a capacitor in the audio circuit acts as the noise filter. So the selection of capacitor and its use in the different parts of the circuit is important. Electrolytic capacitors are polarized so always connect with correct polarity otherwise, it will explode. Disc capacitors are non polarized so they can be connected either way round.
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