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Ultra Bright LED Lamp for AC230V

This ultra-bright white LED lamp works on 230V AC with minimal power consumption. It can be used to illuminate VU meters, SWR meters, etc. Ultra-bright LEDs available in the market cost Rs 8 to 15. These LEDs emit a 1000-6000mCd bright white light like welding arc and work on 3 volts, 10 mA. Their maximum voltage is 3.6 volts and the current is 25 mA. Anti-static precautions should be taken when handling the LEDs.

The LEDs in water-clear plastic package emit spotlight, while diffused type LEDs have a wide-angle radiation pattern. This circuit (Fig. 1) employs capacitive reactance for limiting the current flow through the LEDs on application of mains voltage to the circuit. If we use only a series resistor for limiting the current with mains operation, the limiting resistor itself will dissipate around 2 to 3 watts of power, whereas no power is dissipated in a capacitor. The value of capacitor is calculated by using the following relationships:

* XC = 1/(2pfC) ohms —————(a)
* XC = VRMS /I ohms ———— (b)

where XC is capacitive reactance in ohms, C is capacitance in farads, I is the current through the LED in amperes, f is the mains frequency in Hz, and Vrms is the input mains voltage. The 100-ohm, 2W series resistor avoids heavy ‘inrush’ current during transients. MOV at the input prevents surges or spikes, protecting the circuit. The 390-kilo-ohm, ½-watt resistor acts as a bleeder to provide discharge path for capacitor Cx when mains supply is disconnected.
The zener diode at the output section prevents excess reverse voltage levels appearing across the LEDs during negative half cycles. During positive half cycle, the voltage across LEDs is limited to zener voltage. Use AC capacitors for Cx. Filter capacitor C1 across the output provides flicker-free light. The circuit can be enclosed in a CFL round case, and thus it can be connected directly to AC bulb holder socket.

A series combination of 16 LEDs (Fig. 2) gives a luminance (lux) equivalent of a 12W bulb. But if you have two series combinations of 23 LEDs in parallel (total 46 LEDs as shown in Fig. 3), it gives light equal to a 35W bulb. 15 LEDs are suitable for a table-lamp light. Diode D1 (1N4007) and capacitor C1 act as rectifying and smoothing elements to provide DC voltage to the row of LEDs. For a 16-LED row, use Cx of 0.22 µF, 630V; C1 of 22 µF, 100V; and zener of 48V, 1W. Similarly, for 23+23 LED combination use Cx of 0.47 mF, 630V; C1 of 33 µF, 150V; and zener of 69V, 1W. This circuit (inclusive of LEDs) costs Rs 200 to Rs 400.
Source: EFY Mag
Read more: http://www.extremecircuits.net/2010/05/ultra-bright-led-lamp.html

Be the first to comment - What do you think? Posted by admin - February 15, 2011 at 11:53 pm

Categories: Lighting Tags: ac light, led lamp, super bright led

Single AA cell drive 5 LED display flashing

This the circuit or schematic diagram inexpensive LED flashlight (LED display) at 5 LED amounts that apply runs on a single aa cell battery 1.2V size AA cell and has a cluster of 5 LED. By it use transistor x2 very the circuit is the character switching regulator boost up voltage 1.2V DC from be 3V DC for apply to LED super bright 5 Pcs. usability circuit be this amounts just press SW1 only.
Source: http://www.members.shaw.ca/novotill/LedFlashlights/index.htm

Be the first to comment - What do you think? Posted by admin - April 30, 2009 at 5:49 am

Categories: LED Flasher, Lighting Tags: led flashlights, led signs, super bright led

Switch-Mode LED Backlight by MAX1698

White-LED backlights are gaining acceptance because they offer higher reliability and simpler drive circuitry than those based on CCFL and EL technology. As a result, the white-LED backlight is increasingly common in PDAs, cell-phones, digital cameras, and other portable devices. A design in which the display is backlit (or frontlit) for extended periods needs an efficient circuit that drives the LEDs with a controlled current, and eliminates the wasted power associated with current-limiting resistors.