How can I achieve Blinking of LED without increasing cost when there are large No of LEDs???

Answer 1

Even easier than using a 555 IC (my first inclination if you want an easily adjustable blink rate and duty cycle, at low component cost) is to just buy a blinking LED from Allied Electronics, part number 431-0096, at a cost of about 45 cents each (plus shipping). Digikey carries some with a blink rate of about 1.5 to 2.5 seconds in many colors, about 80-90 cents each.

Answer 2

The easiest way to set the blink speed is with a 555 chip.

In order to drive a large number of l.e.ds they can all be wired in series and have a single current-limiting resistor, or each one has to have its own resistor and each l.e.d.+resistor connected in parallel. You can't just connect l.e.d.s directly in parallel.

You could also have more than one series l.e.d + resistor string, each string being in parallel.

Using the bi-polar 555 the maximum number of parallel strings you could drive is 10 (at 20mA each)

The number of diodes in series which you could drive from the 555 will depend on their colour and therefore their forward voltage.

The 555's Vmax is 18 and you will have to allow for the drop across the current-limiting resistor.

Answer 3

Assuming you are using a series or parallel connention, the most cost effective way to make them "blink" is to use a small powering circuit with a solid-state component. For example, find a 555 (industry standard) IC any poke around the web for -555 timing circuit- hook up the output, and ground it.

Or another way is to get a voltage trigger (say of the operational voltage of your LEDs, found on the packaging somewhere) and hook it up to a small disc capacitor. Look for -voltage trigger circuits-

And the easiest way............................................................................

Don't solder a wire in the cicuit, the touch it to the point a which it is supposed to be soldered at your desired interval.

Answer 4

nope it is impossible ...closing your eyes when you sneeze is an involuntary muscle reaction it cant be helped or stopped