How to turn on & off an LED continously for 1 second?

[netfreak]

Please help me the simplest possible way to turn on & off an LED continously for 1 second.
Please don't suggest me to get it done by micro-controller, help me achieve my goal by the most possible and easiest way.

 

[RoshanBBQ]

Maybe you should hook up the LED to a sinusoid voltage source. Turn the voltage source on for 1 second then turn it off.

 

[NascentOxygen]

Please help me the simplest possible way to turn on & off an LED continously for 1 second.

Hi netfreak! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

Usable over a range of DC voltages and currents, the NE555 timer IC can drive a LED with a square wave.

 

[netfreak]

@roshanbbq , no no using AC won't be a good option at all

Usable over a range of DC voltages and currents, the NE555 timer IC can drive a LED with a square wave.

Yes I have just bought 555 IC timer and will try using it tomorrow. . .
For now I was just wondering that by using simple RC circuit, is there anyway I can continously blink the LED on and off for 1 second? I can't get any way to make it work but can you people please help?

 

[gneill]

@roshanbbq , no no using AC won't be a good option at all




Yes I have just bought 555 IC timer and will try using it tomorrow. . .
For now I was just wondering that by using simple RC circuit, is there anyway I can continously blink the LED on and off for 1 second? I can't get any way to make it work but can you people please help?

No, a simple RC circuit, without other "active" components, is unable to do much other than charge or discharge the capacitor once and once only. You need something that will provide a bit of logic and switching, such as the 555.

It's not clear why you want to accomplish this task, but I will point out that it is possible to purchase LED's with a built-in circuit that makes them blink at a rate of a few flashes per second. A suitable web search will find them. Good luck!

 

[netfreak]

um ok ok , now am getting lil step by step now. . .

And yes I have got that LED as well that has builtin circuit which makes it flash every second but I just wanted to achieve the same using RC or using inductor alongwith it and simple components like this

Many thanks to all of you for guiding me so much :) Today I'll try achieving the task by using 555 IC :)

 

[ajbriggs]

Hi Bud,

Use the 555 timer circuit attached and this website for resistor and capacitor values kpsec.freeuk.com/555timer.htm

 

[netfreak]

Hi Bud,

Use the 555 timer circuit attached and this website for resistor and capacitor values kpsec.freeuk.com/555timer.htm

Wow that was of great help as there is lot of such stuff present on the website that made me aware of many things that I didn't know about 555.
I want to ask one thing here. . . On the website its written : "A low frequency astable (< 10Hz) can be used to flash an LED on and off, higher frequency flashes are too fast to be seen clearly. Driving a loudspeaker or piezo transducer with a low frequency of less than 20Hz will produce a series of 'clicks' (one for each low/high transition) and this can be used to make a simple metronome. "

So does it mean that I must choose my C1=10uF ?(as my purpose is to blink the LED for 1 sec ON and 1 sec OFF)

 

[NascentOxygen]

So does it mean that I must choose my C1=10uF ?(as my purpose is to blink the LED for 1 sec ON and 1 sec OFF)

I would probably choose C1=2.2μF (or use a pair of 1μF caps in parallel).
Note that electrolytic capacitors have wide manufacturing tolerances, perhaps as much as +100% and -50% so you should expect to have to adjust R or C to obtain precisely 0.5Hz if that's what you are aiming for.

 

[netfreak]

I would probably choose C1=2.2μF (or use a pair of 1μF caps in parallel).
Note that electrolytic capacitors have wide manufacturing tolerances, perhaps as much as +100% and -50% so you should expect to have to adjust R or C to obtain precisely 0.5Hz if that's what you are aiming for.

Okay :) Thankyou very much for your guidance:) I'll definitely come here with my results and let you all know how things turned out for me :)