LED Flasher

Mains Powered White LED Lamp

Did it ever occur to you that an array of white LEDs can be used as a small lamp for the living room? If not, read on. LED lamps are available ready-made, look exactly the same as standard halogen lamps and can be fitted in a standard 230-V light fitting. We opened one, and as expected, a capacitor has been used to drop the voltage from 230 V to the voltage suitable for the LEDs. This method is cheaper and smaller compared to using a transformer. The lamp uses only 1 watt and therefore also gives off less light than, say, a 20 W halogen lamp. The light is also somewhat bluer. The circuit operates in the following manner: C1 behaves as a voltage dropping ‘resistor’ and ensures that the current is not too high (about 12 mA).
The bridge rectifier turns the AC voltage into a DC voltage. LEDs can only operate from a DC voltage. They will even fail when the negative voltage is greater then 5 V. The electrolytic capacitor has a double function: it ensures that there is sufficient voltage to light the LEDs when the mains voltage is less than the forward voltage of the LEDs and it takes care of the inrush current peak that occurs when the mains is switched on. This current pulse could otherwise damage the LEDs. Then there is the 560-ohm resistor, it ensures that the current through the LED is more constant and therefore the light output is more uniform. ..
Source link:http://www.extremecircuits.net/2010/07/mains-powered-white-led-lamp.html

Be the first to comment - What do you think? Posted by admin - May 4, 2011 at 8:10 am

Categories: LED Flasher, Lighting Tags: high power led display, led display ac current

Digital Dice circuit

A electronic friends was seeking a play circuits in your free time,a cheap and easy to made.This dice digital circuit would be a favorite of everyone, by using it to display the numbers.
When you switch to a spin button or it like is tossing a dice. Looks like a random form normally.
A heart of this circuit,an a stable oscillator 1Khz with IC 555 and RC networks,it will be output to IC2 is Decade counter IC – 4017.
When I turn off the spin switch, it will be converted to a binary input with a diode matrix D1-D9 (1N4148 or number 1N914) and then changed to a 7 segment display with a decoder drive IC No. CD4511 (IC3).
The brightness of the numeric display, may be customized by adjusting the value of R3.

Be the first to comment - What do you think? Posted by admin - April 11, 2011 at 8:08 am

Categories: Digital, LED Flasher Tags: cd4511, digital game, simple game circuit

Low Supply Rail Detect voltage

Here’s a simple low supply rail detection circuit that costs peanuts and takes just 20 minutes or so to make. Its power consumption is quite low, so it could easily be built into battery-powered devices. Instead of using an op amp, the circuit is built around three low-cost transistors (Q1-Q3). Diodes D1-D3 form a 1.8V voltage reference (Vref) for the emitter of Q1. If the voltage across the voltage divider formed by R1 and VR1 is less than this, Q1 turns on and supplies Q2 with base bias current.
This turns on Q3 in proportion to this bias current which then drives LED1. The brightness of the LED gives an indication of the severity of the low voltage condition. The brighter the LED, the lower the supply voltage. Trimpot VR1 is adjusted so that LED1 just comes on at the desired low-voltage point. The current consumption is typically less than 2mA when LED1 is off. Finally, the value shown for RLED is suitable for 6-12V operation. For other voltages, RLED can be calculated using the formula RLED = (Vcc – 1.8)/0.01 (this equates to a current of about 10mA).
Author: Trent Jackson
Source: http://www.extremecircuits.net/2010/05/low-supply-rail-detection.html