LED driver options?

[kleme]

Im building a lamp with a 3w cree LED, and I'm using a 7.4v battery pack. I've found this driver to go with it. Are there any cheaper alternatives that I could use? Im putting it in a cube enclosure so shape and size are not a problem. I've looked on DX but im not sure what I'll need....

 

[bstrickler]

After a quick 2-3 minute search on DX, here's a list of drivers compatible with the voltage you're using:

http://dealextreme.com/details.dx/sku.26108
http://dealextreme.com/details.dx/sku.7425
http://dealextreme.com/details.dx/sku.3256
http://dealextreme.com/details.dx/sku.25517
http://dealextreme.com/details.dx/sku.26107 (same as 108, but this one doesn't have memory)

If you're going to be driving 5 3W emitter's, this should work
http://dealextreme.com/details.dx/sku.26106

 

[kleme]

Thanks for the info, ill check those out!

 

[bstrickler]

You're welcome

~Brian

 

[TorchBoy]

If you've got a few minutes to browse it, you might also like to check out the link in my tagline.

 

[kleme]

Brian,

I checked out the ones on DX, I'm lookin for a 700mah driver, so i think the only one that would work would be this one. But its on backorder and it seems like it isnt reliable from what the sites forums say. Also, i plan on using a 7.4v battery, and the threads say that this driver would bump the Vf to 1000mah which would be to high for my application. So, could I use a lower voltage battery, what would be the difference of using a lower voltage battery with the same capacity? Would it change the brightness or run-time of the lamp? And could i hook up a pot to it, i read one thread about doing that but it seemed pretty complicated... is there a noob guide somewhere?

Mike
​

http://dealextreme.com/details.dx/sku.3256

 

[TorchBoy]

BTW, mAh is capacity (eg, of a battery) and mA is current. Some drivers output a constant current, while the output of others varies depending on the input voltage. I much prefer the constant current output ones. Edit: I've just added that info to the table.

http://www.dealextreme.com/details.dx/sku.13557 might do - there's a post there that says the latest ones work from 5-25 V.

 

[kleme]

Got the units mixed up there. What I meant was that if i have a 1000ma of current to the led, others have found that it does not make the LED brighter, but it does make the LED very hot. So, I'm putting this on my head and don't want a tattoo on my head lol jk. At 700ma, it will extend the life of my LED and i will have longer battery life (which is the reason why I'm modding this in the first place :candle: lol).

Thanks for the link Torchboy, I checked out the forum chat on that one, and it seems that this driver used to be sent out with wrong specs and people were happy with the 700ma output, but now they've changed it to function to the correct specs that it is advertised at. So its now outputting 300-350ma.

This one seems very promising though. Good price, and it has good support from the site. Seems like it hit all the points I needed :thumbsup:. Is this the manufacturers website? Anything I should know about them before I pick this one?

 

[TorchBoy]

Thanks for the link Torchboy, I checked out the forum chat on that one, and it seems that this driver used to be sent out with wrong specs and people were happy with the 700ma output, but now they've changed it to function to the correct specs that it is advertised at. So its now outputting 300-350ma.

The wrong specs was the "320-350mA" in the title, something which has never been fixed. Give or take a conflicting report, the output has always been 650-750 mA, which fits with the (nominal) 3 W claim. I ordered one myself after Roozl and drknss99 claimed they were only 300 mA; I measured around 650 mA, and there are others who claim it's still 650-700 mA. One reason for their wonky results may be poor test equipment, since the switching frequency may be too high for their meters to read current accurately, or perhaps just poor test methods. I've had a bit of trouble there, because inserting a (possibly high resistance) ammeter into a circuit can change circuit conditions a lot. Hey, maybe they just measured the input current? :mecry: :shakehead Who knows?

This one seems very promising though. Good price, and it has good support from the site. Seems like it hit all the points I needed :thumbsup:. Is this the manufacturers website? Anything I should know about them before I pick this one?

I think so and I really don't know, respectively. I only got around to adding Sure's two drivers yesterday, and I haven't heard anything about what the company is like to order from. I reckon give it a go and let us know.

 

[kleme]

Cool, I think I will try Sure Electronics. They seem like they are pretty accommodating to their customers. I had a bad experience with DX to get the lamps I used, and they weren't very customer friendly, and I don't like the low reliability of the products they ship.

I had a question about the hook up that I need to make. I've included a pic to make it more clear of what I'm looking at. I took off the battery pack that came with the lamp and it had three wires coming from it, i was only expecting two. There was a potentiometer in the pack and a small driver I think. I was wondering what the yellow wire goes to??? It went to a connection labeled "SW".

So if I wanted to add a potentiometer into the new pack, where in the circuit would I put it... I've included a pic of how I think the new pack would be put together without a pot. The buckpuck driver by luxeon has the leads that go to the pot already shipped with the pot connected which is idiot proof. Can I even add a pot to the sure electronics driver? If not, I'm not worried, just go with out it, but I still need to know if i should worry about the yellow wire coming from the LED, in my new pack, should I just cut it off if I don't add a pot???:thinking::thinking:

 

[TorchBoy]

I think I've found your problem. You're trying to insert a fried egg in your circuit. :thinking: Seriously though, I don't know. If you chose a driver with a set resistor you could maybe use a potentiometer in its place to adjust what the driver is trying to output.

SW for "switch modes"?

 

[HarryN]

Torchboy - Thank you for the very nice database of drivers. You found some interesting ones.

When you get bored, I would like to suggest adding in the Buckpuck. Here is a link. http://ledsupply.com/led-drivers.php

I am just an end user of their drivers (and others as well) - not in any way related to them.

 

[kleme]

Ok, i think im going to go with the sure electronics driver. I'll be the guinea pig for the group lol. Should take a while for all the different parts that im ordering to come in from China, but I'll keep you posted.

I want to sketch out a schematic soon of what the setup will be like. I want your guys feedback, so that when I get the parts shipped, all I have to do is wire it up.

I'll be back...

 

[TorchBoy]

Thanks Harry. I've had Led Supply on the "Not Yet Added" list for ages. I had another look a couple of days ago and there were so many different varieties of Buckpuck, and in four different current outputs, that I gave up again. I guess I'll just lump each type (eg, Buckpuck, Micropuck etc) together.

Keep us posted kleme.

 

[kleme]

Quick question,

Im thinking of just buying a mobile phone charger, its basically what I want to build, but for way cheaper.

Only one hitch though, I can only find chargers that output around 5v and 450mA (which is ok). Would that voltage be to high for my LED? I don't know how it would react to this voltage, could anyone enlighten me?? (no pun intended, well actually yea it was... )

 

[TorchBoy]

Yes, 5 V would be too high. Even if it wasn't, LEDs should really be run in a current controlled fashion, which you could basically do by using a resistor to drop from 5 V to what you do want. http://ledcalc.com/

And I've now added all those pucks etc. I guess I'm still impressed with the versatility of the MicroPuck.

 

[VegasF6]

Quick question,

Im thinking of just buying a mobile phone charger, its basically what I want to build, but for way cheaper.

Only one hitch though, I can only find chargers that output around 5v and 450mA (which is ok). Would that voltage be to high for my LED? I don't know how it would react to this voltage, could anyone enlighten me?? (no pun intended, well actually yea it was... )

Won't the phone charger be current limited to 450mA? So voltage shouldn't be a problem, it will simply output whatever the forward voltage of the led is at 450mA I am pretty sure. With a transformer it probably wouldn't last long, but a switch mode power supply should be fine. Right?

 

[kleme]

This is the pack I would like to use, it has huge storage, great packaging, minimal modification, and did I mention cheap!

Sanyo Eneloop Mobile Booster

What do you guys think about just running this pack straight to an LED?

Heres the specs:
Output max: 5v at 500mA
Capacity: 5000mAh

 

[J_C]

You don't really want to direct drive an LED from a supply that is voltage regulating at 5V rather than current regulating. Although some may list an acceptably low max current, it's not trying to stop supplying power at that current, it is trying to maintain 5V and will probably either fry the LED or shut off because it can't stay at 5V. There are ways you could make that work, if you took the 5V output to an intermediary stage, a proper LED current regulated driver though the 450mA @ 5V supply isn't enough current to meet your goal for LED current. You could also, or instead, use a series resistor to run the LED at the max current any particular 5V supply is capable of, though often with consumer grade electronics it is better not to try and run a supply at it's max rating, it's better to run them at about half to three forths of the rating to increase lifespan of the supply. Industrial equipment is usually rated more conservatively so you don't have to derate like this.

 

[VegasF6]

Hmm. I have a Kyocera charger speced at 5V 350mA that has been running 8-10 hours a day for several months with no problem. (driving a spare cree P4 housed in a copper cap). It pushs 3.245 volts at the emitter right now (warmed up). If I recall it was actually more like 390 mA though that was some time ago.

In the case of a cell phone, I am sure the lithium battery is charged CC/CV, would those electronics actually be in the phone or in the power supply?