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how to make a cheap led lamp?

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sonalnew

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i want to know about that how can i make a led lamp with sufficient light to study at night and if possible without transformer
 

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pauloynski

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Try this . Take about 30 cheapo white leds and connect all in series. Also connect in series a 1kΩ/5W resistor and a diode (1N4004). If it flickers filter the rectified voltage using a 4.7uF/250V cap. You can adjust the current by changing the value of the resistor and/or decreasing the value of the cap. Point all leds to the same direction. This can work fine for a mains voltage of 127V. Be aware: no isolation from the power network.
 

pranam77

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You may consider this simple design of an LED based emergency light published in EFY Magazine. This circuit uses 6volts 4.5Ah battery which is charged when the power is available and illuminates 12 white LED's in case of power failure.

http://www.electronicsforu.com/elec...pdf&title=Automatic Low-Power Emergency Light

Or in case you decide to go without a transformor, the led's can be driven directly through a capacitor and diode combination as shown in this link.

http://www.discovercircuits.com/H-Corner/AC-Powered.htm

Hope it helps you. Cheers.
 

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pauloynski

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Hi pranam77: I´ve tested the circuit posted in http://www.discovercircuits.com/H-Corner/AC-Powered.htm . The problem I´ve found is that in this circuit the current assumes a sinusoidal form, with a high peaking value. Using very cheap leds this caused 3 of them to fail in 1 month. Using rectification and filtering the current is almost constant and now the circuit has been working fine for almost 2 years.
Regards.
 

pranam77

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pauloynski said:
Hi pranam77: I´ve tested the circuit posted in http://www.discovercircuits.com/H-Corner/AC-Powered.htm . The problem I´ve found is that in this circuit the current assumes a sinusoidal form, with a high peaking value. Using very cheap leds this caused 3 of them to fail in 1 month. Using rectification and filtering the current is almost constant and now the circuit has been working fine for almost 2 years.
Regards.
Yes..i do agree with your words. We need to put our experiences and skill to make some things work better as per our requirements. Thanks for the valuable info. Cheers
 

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