LED Panel Emergency Lamp. Home Utility Circuit 21


LED-PANEL-3

You can make an LED Emergency lamp easily using the LED Panel available now. The lamp turns on when the power fails and turns off when the power resumes. When the mains power is available, the 12 V 7.5 Ah battery charges. Since LED panel is used, the emergency light can have a back up time of many hours. You can make 9 Watt or 18 Watt Emergency lamp using the circuit presented here.Its Backup time will be 10 Hours.Its cost will be around Rs. 950. Of these, the battery alone costs Rs.800. If properly maintained, the battery will last more than 4 years.

Designed and developed by D.Mohankumar

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Invisible Tester. Simple Design 8


IR-DIODE-TESTER-CIRCUIT-2Title of the circuit is deliberately given because it is used for testing the Photo diodes, Infrared LEDs, Photo transistors etc working in “Silent Mode”. How can we confirm an Infrared LED is working or not. It gives No visible indication. It is working and emitting Infrared rays but the IR rays are beyond our spectral response and we can’t see it. So this simple tester will help you to check whether such devices are good or bad before using in a circuit or even during trouble shooting. Not only one function the tester doing . It can test, all diodes, Capacitors, LEDs etc. Its cost is just Rs.10 but it is a worth tool.
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Tristate Battery Level Indicator


Here is a simple but useful battery level indicator to monitor the battery terminal voltage.Efficiency of the battery reflects in its terminal voltage. A good Lead Acid battery will show 13.8 volts in the fully charged state and if it is below 10 volts, the battery needs immediate charging. If the battery voltage goes above 14 volts, it is in the overcharged condition. This circuit uses a two lead bicolour LED to indicate three battery levels. If the voltage is below 10 volts, the Green part of the LED lights and if the voltage is above 14 volts, the Red part lights. If the battery voltage is between 10 to 14  volts LED remains off.

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