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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Automatic Lamp


Here is a possible solution to prevent the wastage of energy if you forget to switch off the bathroom or terrace lamp. Once it is switched on, it stays on for 22 minutes and then automatically turns off. The lamp will turn on only if the switch is turned off and turned on again.Save Energy. It is precious.

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Long range uPD6121 IR Transmitter


Here is a long range Digital IR transmitter. It is a precision IR transmitter suitable for TSOP 1738 IR receiver module. Unlike other IR transmitters, this circuit is highly reliable and gives fail proof operation.

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Personal Alarm


If you feel threatened or need an urgent support in a crowd, use this alarm to catch the attention of others. It generates a loud siren simulating that of the Fire brigade which is enough to get support from others. A single press on the switch can activate the siren for 2 minutes and then it automatically stops. It is too small enough to keep in the pocket or hand bag.

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Bread board Regulated Power Supply


You can use this multi voltage power supply for the bread board projects. Most of the circuits require regulated power supply for errorless operation. This power supply can give regulated 12V, 9V, 6V and 5 V. Charger point for battery charging and Test point for LED and Buzzer are also included.

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