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Author Topic: Power 3W LED help requried!  (Read 3461 times)

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Offline kl22Topic starter

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Re: Power 3W LED help requried!
« Reply #30 on: May 16, 2011, 01:38:54 AM »
That's okay TrickyNekro. Thanks anyways!

So you second Soeren's solution?

As I mentioned earlier I'm just about to order the parts, will let you know the status :D

Thanks again to you and Soeren for all the help!

Offline TrickyNekro

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Re: Power 3W LED help requried!
« Reply #31 on: May 16, 2011, 02:36:28 AM »
Help me a little with my English here...

If you mean whether I support Soeren's solution, yup...

I have much less than half the years of service that Soeren has, so...
If he say's it's gonna work, it will.... Never tried myself, but you have to trust this guy ;)
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline kl22Topic starter

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Re: Power 3W LED help requried!
« Reply #32 on: May 16, 2011, 04:42:14 AM »
Oh I don't doubt Soeren:)

Soeren has helped me before seems to ha e a 100% accuracy rate so far

Anyways thanks for all your help. Hopefully Ill get the parts by the end of this week so I can get a proto out to see it working.

I do have one question can I put all the LEDs, the fet and the other IC on the same heatsink?

Offline Soeren

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Re: Power 3W LED help requried!
« Reply #33 on: May 17, 2011, 02:45:01 PM »
Hi,

I do have one question can I put all the LEDs, the fet and the other IC on the same heatsink?
Yes, but only if you isolate them. The drain on the MOSFET (were the LED connects in the schematic) is connected to the metal tab. Since I don't know your LEDs I cannot say if one of their pins connects to any conducting material the heatsink will come in touch with.
The other IC is... What?

You can get some heat conducting, electrically isolating washers for a TO-220 and if the LED has got any exposed parts towards the heatsink, I guess whoever sold the LEDs should have some that fits the LEDs.
When mounting the MOSFET, use an isolating bushing made for the purpose - then the screw won't short them (or use nylon screws).

The heatsink should be rated for the total power it sees (and calculate with an ambient temperature of ~40°C (it's the air right next to the heatsink). Any higher and touching it may be less pleasant.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline kl22Topic starter

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Re: Power 3W LED help requried!
« Reply #34 on: May 17, 2011, 09:59:47 PM »
Hi Finished the circuit it works
but with one problem why it is acting like a strobe light but really fast. Do i need to put in a cap somewhere? works fine if I give it 5V input instead of PWM.

EDIT: nevermind it works. It was my fault the frequency of the PWM wasn't set high enough.

Special Thanks to Soeren & TrickyNekro for helping me get this to work.
« Last Edit: May 17, 2011, 11:24:03 PM by kl22 »

 


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