Low cost LED Driver. Start Up Project 22


2ALED Drivers are used to drive High Power LEDs that require more than 100 mA current. A typical 1 watt LED consumes around 100-300 mA current while a 10 watt LED consumes 600 mA to 1 Amps current. So a resistor to drop the current is not sufficient since it heats up when high current passes. Moreover, the high power LEDs require a Constant Current to give steady brightness. So LED Drivers are used for this purpose. A typical LED driver has two sections. An SMPS converts 220V AC to DC and a Constant Current Generator Circuit provides Constant current to LED. But LED Drivers are costly units and the cost range from Rs. 150- Rs.600. We can make a Low cost LED driver just for Rs.15. Try it.
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LM 317 Voltage Regulator. Design Note 16


LM317-T
LM 317 is the popular adjustable voltage regulator IC commonly used to make variable power supply. It is a three terminal device with Input, Output and Adjustment pins. Actually, LM317 is an Op Amp with relatively high output current capacity. The Inverting input of the Om Amp is Adjustment pin, while the Non-inverting input is set by an internal band gap voltage reference which produces a stable reference voltage of 1.25 volts.
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Familiarize Electronic Components Part IX – Voltage Regulators


Voltage Regulators are used to give regulated power to a circuit. Most of the circuits using CMOS devices require well regulated power supply. Zener regulated power supply is simple but less reliable than the power supply using Fixed Voltage regulator IC. 78 XX series ICs are Positive voltage regulators while 79 XX series ICs are  Negative voltage regulatorsLM317 and LM338 are Variable voltage regulators.

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Inverter Battery Charger with Cut Off


The Blog Stat shows that most of the readers are interested in Battery Maintenance as indicated in the Tag cloud. So I wish to post a Friendly Charger circuit for the battery. This Battery charger can replenish any kind of 12 V Inverter battery or Car battery and keep it in top condition. The charger never allows the battery to Over charge or Deep discharge. It automatically charges the battery when its terminal voltage drops below 12 volts and switch off the charging process when the terminal voltage rises to 13.5 volts. So that the battery can be kept unattended.

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