REQ: 3-mode LED buck/boost driver up to 1A

[chandelier7]

Dear other flashlight addicts,

I am planning to get some flashilghts at DX, but I really want three modes.
For those small flashlights with an AA or even AAA, I really don't see the point in throwing lots of light and only having a single mode, so having no choice to use the flashlight longer than eg. half an hour without replacing the battery... *stop rant* Sorry, it's MY preference!

I read a lot through the web (and in here), but I don't find the wanted driver.
I would wish for...
1) an effective circuit to work from one and two AAs, (preferably even from a Li-Ion also)
2) with 3 modes only

What I often found recommended is the sku 7882 at dealextreme (but it has got 3 groups of modes and the simplest groups has 5 modes) and the and the hint, that there can be found a similar driver at kaidomain, which with it's first group of 3 modes seems fine for my purposes. But I'm not sure if I really found it. (COuld it be SKU: S005872 ?) The search-function on KD is bad and I've had a hard time to look for stuff over there, and mostly, there's not even an acceptable description on their product's sites, so I'd be glad if someone could point me to it.

Of course I'd be glad about any other 3-mode driver that suits my requirements! Well, two modes would be ok too...

Or should we design our own? It's not that I'd have too much time on my hands, but if there are a few more people out there, among them some electronics freaks (?), we could possibly do this together? Soldering and making a pcb is not THAT difficult...

Cheers,
Dominique

PS. Hey, it's the first time I am posting here, so hi everybody, I hope you're doing fine!

 

[SkipH]

I got a DX 7882 last week and can't get it to work.

I've been in contact with another user here (Hrvoje) who has one and got it to work.

Meanwhile, I've ordered the KaiDomain one you mentioned SKU 005872, which is the same as DX SKU 15880 (currently back-ordered).

Hrvoje also used a DX 15880 in a light mod in the past. I'll see if I can find the thread and post it here for you to read.

Here's the thread about his mods:

http://www.candlepowerforums.com/vb/showthread.php?t=219166

If and when I get the KaiDomain driver, I'll post back about it.

 

[linterno]

You could replace the driver's microcontroller an get the modes you want.

Read this post I made in another thread about how to replace it and implement as many modes as you want with the percentage of brightness for each mode and the minimum off-on time to switch from one mode to the other.

 

[chandelier7]

@SkipH
I'm glad you confirmed that 005872 was the right part! So I'll get 3 or 5 of those for possible modding actions when I'll have the flashlights. And I'm glad you linked to Hrvoje's interesting mod!
I remember others mention here having a problem with this part, and they had to shorten a certain connection on the circuit, I think. Could your problem be related to this?

@linterno
Wow, that's an interesting option! To date, I've only done small an analog (mostly audio) electronics projects, but I sometimes stumbled upon exciting microcontroller projects. This is one of them and what you describe seems really easy to do, so it's quite tempting! Write your own modes! Then you could later modify them or add hidden extra modes (which aren't accidentally switched on like in some of the usual drivers...)
In your post it sounds if you're not using that Picaxe solution, but a usual microcontroller. But did you try what you described in your post by yourself?
Ah... also, I always wonder what those percents in the modes mean: It's probably not really brightness... is it the mode's current in relation to the maximum current?


Thank you both for those very interesting infos!
Well, I'll order some stuff tomorrow and get the 5872 and see if I will be glad with it's three mode programm.

Cheers,
Dominique

 

[SkipH]

@SkipH
I'm glad you confirmed that 005872 was the right part! So I'll get 3 or 5 of those for possible modding actions when I'll have the flashlights. And I'm glad you linked to Hrvoje's interesting mod!
I remember others mention here having a problem with this part, and they had to shorten a certain connection on the circuit, I think. Could your problem be related to this?

Cheers,
Dominique

Dominique:

No, the DX 7882 is a 'newer' one, a blue one, not the white one as shown on DX. (I guess they sometimes don't update their pictures).

It has a small resistor where the white one and some earlier blue ones were missing a connection. I jumpered that but it didn't help.

Therefore I thought I'd give the KD 5872 a try, as Hrvoje had good luck with it.

Unfortunately, my order at KD is now showing 'backordered', whereas all the individual items were either 'ship right away' or 'ship in 1-3 days'.

I'm in no hurry for the 5872 or the 2 other small items I ordered, so will just wait and see what happens.

 

[linterno]

Dominique:

In your post it sounds if you're not using that Picaxe solution, but a usual microcontroller

The posted code is and work with PICAXE-08M.

But did you try what you described in your post by yourself?

Since I don't have any available driver to test I did test but with a PICAXE-08M (not SMT) and a regular 5mm LED and it worked. I don't see why it would not work with the driver.

Ah... also, I always wonder what those percents in the modes mean: It's probably not really brightness... is it the mode's current in relation to the maximum current?

This is the percent of the PWM period that the LED is on (the duty). The PICAXE-08M PWM frequency is 10KHz. This percents translate to brightness to the human eyes.

Juan C.

 

[chandelier7]

Dominique:

This is the percent of the PWM period that the LED is on (the duty). The PICAXE-08M PWM frequency is 10KHz. This percents translate to brightness to the human eyes.

Juan C.

Aaah, of course! I had the vague idea (but didn't really think about it) that the circuit would adapt the current, but now I understand how it works! Of course, it's an easy solution. It's just a bit a pity that this way, you're not taking advantage of the higher efficiency of the LED at less power (/current). (But maybe, working in short cycles, it's still more efficient than in full mode (?), because the LED has more time to emit the heat and stay cooler)

Thanks again!

Cheers,
Dominique