# luxeon 3W strobe



## butch (Apr 10, 2006)

Hi,

Has anyone tried to build a strobelight with the lux 3W LED? Just like the gladius.
If so I would be interested in schematics etc.

Thx


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## sp5it (Apr 11, 2006)

LM555 with mosfet should do the job.
Mike


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## butch (Apr 11, 2006)

any schematics?


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## sp5it (Apr 11, 2006)

Look here: http://www.discovercircuits.com/L/lite-flash.htm
You should find what you need.
This will help in designing: http://ourworld.compuserve.com/homepages/Bill_Bowden/555.htm

Mike


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## butch (Apr 11, 2006)

Thanks alot. This will get me underway.


But where does the Mosfet come in?


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## sp5it (Apr 11, 2006)

Drive mosfet from timer output. Mosfet will drive led.
Mike


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## legtu (Apr 11, 2006)

You can also use a medium/high power transistor or LDO in place of the mosfet.


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## butch (Apr 11, 2006)

Ok, I've managed to create a 3Hz strobe with a normal led. Circuit was a astable LM555. 

The Luxeon 3W Led has a maximum of 1A current. So to switch the luxeon led I have to use the output of the 555 and control a mosfet or high power transistor. 
How do I do this?




and will the mosfet be able to manage the frequency?
What about the current of 1A? Will this not affect the 555?


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## sp5it (Apr 11, 2006)

Like that: http://www.moreleds.com/pwmcircuit.jpg
Mike


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## sp5it (Apr 11, 2006)

Like that: http://www.moreleds.com/pwmcircuit.jpg
Bipolar transistor able to handle 1A current.
Base to output of 555
Emmiter to ground (-)
Collector to (-) of luxeon.
Don't forget to use current limit resistor for Luxeon.
Mike


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## Corona (Apr 11, 2006)

DON"T FORGET A CURRENT LIMITING RESISTOR!

I normally hang in the laser forum but strayed here because I'm a LED nut and avid modder besides...anyway, in Real Life I'm a power electronics engineer so maybe I can help...

butch - post your battery / operating voltage and I can recommend some specifics for the MOSFET, current limiting resistor (else you can kiss your Luxeon III goodbye) and some other pertinent stuff...

For a strobe effect, you want a short duty cycle (like a Xenon tube discharge) - around 10% duty cycle (10% ON, 90% OFF) gives a pretty decent flash. Staying at a low duty cycle also reduces heat and losses in th LED, FET, and current limiting resistor (= extended LED and battery life and eliminates need for any heatsink on the Lux)

BTW yes the FET can easily handle 3Hz - we routinely use 'em upwards of 300kHz - so 3Hz is basically DC to them 

If there's any significant interest in such a thing I might get in a little deeper...


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## IsaacHayes (Apr 11, 2006)

I want to do this only switch a light on/off that is using dual BB500 constant current step up regulators.

That means whatever circuit I use to strobe must be able to switch 2+amps of current. Also would want soft switching between on/off/strobe. I need to talk to goldserve some more about the flupic. If only my light were DD the flupic would be perfect...


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## butch (Apr 12, 2006)

Ok, thx for the replies.


I want to use Two CR123 batteries, so the power will be 6V.


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## sp5it (Apr 12, 2006)

Look here: http://www.e-f-w.com/community/images/content/led_drivers/555_MOSFET_pwm_driver.gif
It is PWM controller, but after little modification you can use it as strobe. 
It is good example ahow to use mosfet to drive Luxeon led.
Mike


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## cmacclel (Apr 14, 2006)

Why not just buy a $20 Flupic board??? Low High Burst 1.2amp + adjustable Strobe.

Mac


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## sp5it (Apr 14, 2006)

Pleasure of DIY?
Mike


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## Builder (Apr 15, 2006)

I built this several years ago as a gag at parties - overdriving a 120mA 10mm to about 500mA from 4AA's. The driver was a Zetex PNP (for high current and low power-loss) with a 2N3906 as the current limiter. Use R=.75/I for the current limiter resistor.

fwiw, the flash duration was designed to maximize the irritation to the eyes - just long enough to register but before the irises could close...

To maximise its nastiness I would choose a LED with as narrow a beam as possible, so the Lumi's 100degree spread is NOT as effective. Unless you spring for a reflector as well...

With the values shown, it will go from 1 flash/2second to a "continuous" beam (while staying under 1/10 duty cycle) - so I could see where I left the car...

Must be good - someone "borrowed" it and never returned it.


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## sp5it (Apr 16, 2006)

Another regulated strobo. 
http://www.moddingtech.de/portal/pics/content/tutorials/ledstroboskop/ledstrobo_schaltplan.png
Mike


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## Builder (Apr 16, 2006)

sp5it said:


> Another regulated strobo.
> http://www.moddingtech.de/portal/pics/content/tutorials/ledstroboskop/ledstrobo_schaltplan.png
> Mike


The circuit just has limiting resitors - it's not regulated.


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## sp5it (Apr 16, 2006)

I mean regulated strobo frequency. 
And of cuurse to use it with luxeon builder need to use proper resistor value.
Mike


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## butch (Apr 18, 2006)

Whats a "Flupic board" and what can I do with it?


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## legtu (Apr 19, 2006)

butch said:


> Whats a "Flupic board" and what can I do with it?



It's basically a PIC(programmable microcontroller) + LDO combo. 

The PIC can be programmed to dim(via PWM), strobe, etc...


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## butch (Apr 19, 2006)

Is it possible to give some more info on this.

Costs of everything, software, etc

Internet sites with strobe examples?

Thx


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## butch (May 2, 2006)

Ok guys, I've managed to make a strobe circuit with 7Hz flash

I used a Luxeon III star. But I have problems with the cycle time. I can't get it lower than 50. Only higher 
What can I do to solve this problem.


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## Builder (May 2, 2006)

If you are using smoke alarm 9v batteries, they only have 300-500mAH capacity, with a fairly high internal resistance - the sag under load is something awful!

What values are you using for the resistors and capacitors?


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## sp5it (May 2, 2006)

Look for software called "555 timer designer" Find it with google.
It will solve your problem.
Mike


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