Dear friends.I want to create a circuit myself to use as tail light for my bicycle.I do not need modes for it.It would be enough if it had a flash mode.
And brightness should be like the light on the video

http://www.youtube.com/watch?v=7qqvE9baOwk

But i use 2 leds and i want to use them by AA or AAA or 9v cell.So please help me to find a good and enough powerful circuit to use for it.Thank you very much.

 

Have a look at Bill Marsden's blog about LEDs, 555 timers, and flasher circuits here. I think that will assist you.

 

Not difficult, but I'm not sure what you what it to do. Can elaborate on it's operation?

Two LEDs only?

Do they both stay on all the time or flash all the time or both (say, for example, by flipping a switch)?

Do you want to vary the flash rate using a knob or will it always be the same?

Do both LEDs flash at the same time or alternate, i.e., one LED on, one off and vice versa?

 

Not difficult, but I'm not sure what you what it to do. Can elaborate on it's operation?

Two LEDs only?

Do they both stay on all the time or flash all the time or both (say, for example, by flipping a switch)?

Do you want to vary the flash rate using a knob or will it always be the same?

Do both LEDs flash at the same time or alternate, i.e., one LED on, one off and vice versa?

Yes i just use two leds, but they must be really bright because it is important to be seen in traffic.


I don't want to vary flash rate.It is ok, if it works on the same flash rate.But leds should flash just once in one second.Flashing can be short.

And two leds should flash at the same time.So i do not need seperate them to create a flip circuit.I think i can connect them parallel.

 

There are tons of lights out there with those specs. You will probably. not be able to build one as attractive, efficient and weather resitant as a purchased light. Unless you have something really unique in mind just buy one and think up another fun project on which to work.

 

Spinnaker makes a good point, you can probably buy something for less money and a lot more durable and weatherproof than you could make by hand.

That said, let's say you still want to make this.

As ke5nnt pointed out, Bill's got a great blog.

Take a look here, specifically at figure 4.2, oscillator #1. This circuit will flash one LED then the other with no extra parts. If you just want two on and off at the same time, you can put both LEDs in series if the voltage from your battery is high enough or in parallel -both would either be connected to Vcc or GND, not one each.

Bright LEDs aren't hard to get - you can get them from eBay (questionable quality, but for this application, you should be fine) or an electronics parts distributor, even RadioShack I think. Look for a rating of 3000 or more mcd and at least a 30° viewing angle. If you can tell us where you'd like to order parts from, we can make some more suggestions.

 

Use an LM3909 ic it will work on a 1.5v battery

http://www.solarbotics.net/library/datasheets/LM3909.pdf

or use a IC7555 timer

https://www.intersil.com/content/dam/Intersil/documents/fn28/fn2867.pdf