Anyone know a good luxeon flasher circuit?

[Leeoniya]

trying to make a flasher thing for my girlfriend so she doesnt get hit by a car when she goes out running, need a circuit with as few components as possible, run off or 1 AAA or anything that size...6V, 3V, 12V lithium photo. whatever. i guess current control is not really needed and there is no real need for PWM voltage control, i know there are 555 timer circuits and transister flasher circuits but i dont think any of them can run with 400-500ma bursts.

thanks.

 

[ledaholic]

http://www.911ep.com/ledstar.html
Check these out. I have one installed on the back of my motorcycle connected to my brake light circuit. They have 3 red (I think amber, blue are also available)1 watt ls's, run on 12v flash 3 times-pause 3 times-pause... Very bright very effictive and compact.
Bob

 

[Leeoniya]

it looks like what i need, except a lot bigger. i just need a schematic, i can build the circuit myself, cause it has to go on a clip or something, it cannot be huge.

thanks tho.

 

[tonyb]

http://www.discovercircuits.com/index.htm

 

[Doug Owen]

You're right, 555s while simple and easy to use are limited to 200 mA or so, source or sink. So use a few dozen mA of that to drive a transistor to switch on the LED. Say a 2N3055 or any other that can handle the current you want. High current FETS are another option.

Doug Owen

 

[Steelwolf]

Leeoniya: This is probably against the spirit of this thread, but do you have a bicycle shop nearby? They usually sell little LED flashers that clip on a bracket at the back of a bike. Some versions have a plastic clip that you can hook to the waist band, some have a strap to tie it around your body or arm. I figure this will be more cost effective than building your own, mainly because of the cost of building an effective housing.

These are usually fairly cheap, use 1 or 2 AAA cells and run maybe 6 red LEDs. This design used to use a LM3909 IC (along with a couple of other components like a capacitor) to handle the boost as well as the blinking.

If you are still adamant about building your own, the site tonyb mentioned is great. The particular page you need is this one. But check around as there may be other useable circuits under other listings.

 

[Leeoniya]

http://www.techlib.com/electronics/flasher.html
ok, i think this is close, i'm looking on this page at the one with the mosfet. can anyone help me gett he proper specs for the components plz? and if i were to vary the flash rate can i do something other than switch the capacitor? if not it's no big deal. but here is what i want to adapt it to. 1W luxeon so prolly around a 3hz flash at 400ma-450ma, so the mosfet has to be able to handle that, i need the specs for the resistor values that will work well with the design. i'm gonna go to digikey and get all of the stuff surface mount. my only concern is getting the appropriate resistance for the LED, which i am assuming goes inline with the power and the collector or emitter of the mosfet. is it a depletion or enhancement mosfet? the schematic looks like depletion. but i dont know. and i want to regulate the voltage across LED by applying a smaller voltage to the gate rather than fully saturating it and using an inline resistor with the LED. now to find out how to only partially turn on the mosfet.

i'm planning on using a 6V CR2 battery.
need component specs! any advice is appreciated
thanks.