I keep looking for, and not finding a 3-mode w/memory, .9v - 4.2v, 750mA - 1050mA, 15mm buck/boost circuit board / driver. That can be used to repair, or replace, or mod all these single AA/14500 led lights that so many of us have and seem to like.
You know, the Trustfires, Ultrafires, AKOray style lights that we all seem to have bought at some time or another. The ones that don't live up to advertised specs, and that would make a great modding project as well as a great EDC light.
In addition, simple features that might even allow us to use this kind of board to create, fix or mod a great number of lights in a variety of hosts with minimal fabrication. I'm thinking that the most daunting issue to use a driver with many different pill / host combination's is the issue of 15mm or 17mm board diameter. That could be worked out within a custom driver board.
Does anyone here have expertise in making this idea work? Is there some-way that WE can come together and get this designed and manufactured within a limited production run?
If we could make it affordable, I'd commit to 8 - 10 units to start.
Please chime in, I'd like to hear your thoughts. It's just an idea at this point, but from what I read, I think as a group we have the skills, and hopefully the money to make this happen!
"You can't get there from here" is a phrase I once heard that comes to mind now.
Doing the math with your numbers reveals that with a 3.4V LED at 1Amp we need 3.4W. Figure the driver is 100% efficient (it won't be), so the power drawn from the battery is 3.4 Watts. This equates to a 3.4 Amp draw on the battery when it is at 1.0 Volt...
At 1.0 Volt to the driver, losses from voltage drop quickly eat a big chunk out of the drivers efficiency. And lower efficiency means even more power is required. Its a vicious circle.
If you're willing to accept a big drop in current at lower voltage, and probably stack two boards (to also get the modes you want) you could squeeze it into a 15mm puck, but it would very closely resemble the performance of what is currently on the market. If it could be designed to sell for cheap it would have happened already.
I don't mean to "rain on your parade" but I've been down this road too.
By the way, count me in for a few of these too, if it can be done.
P.S. I've used this part before: http://www.linear.com/product/LTC3425 Claims 80% eff. for 1.2V in and 3.3V@1A out, but it would be tough to fit it on 15mm board. Oh, and it's boost only.
I do appreciate the feedback. I don't have the technical knowledge, but I figured the skills were here.
Question. Do you think that a circuit board like that found in the AKOray K-106 (programmable), could be made to work reliably? To work with AA alkaline's as well as 14500's.
That single cell, small light w/ modes is very close to my ideal EDC light.
Shiningbeam sells a 3-mode (H-M-L) driver, but it only works lithium cells.
Unfortunately, I,m not familiar with that driver. Are you able to see what parts are used in this driver? Does anyone else out here know? If it uses an ATtiny13 then you're "in like Flynn" as these can be reprogrammed. But I fear that the mode controller may only be a non-programmable type.
My EDC is an AKOray K-102 (same as K-103 but SSC LED rather than Cree) but it is AAA single mode and now has an XP-E and a driver I built using a TPS61200 IC. That IC is slick because it does inductive boost when the battery is below the LED voltage (typical alkaline cell) and also handles linear down mode (current regulation) when the battery voltage is above the LED voltage (typical Li-Ion cell). I have it set for 250mA which, for me, is a good compromise between brightness and run-time. But I digress... sorry.
Sounds like this one from SB is the one you want. Works from 0.9V-4.2V and meets just about every requirement from your original post. I have it in a Sipik SK68 and it works great.
JohnnyMac, Something ain't right with that driver from SB. The specs look good till you read a little deeper:
* Regulated circuit board designed for Cree XM-L, XP-G and XR-E emitters ^Good
*3 modes: Low>Med>High ^Good * Voltage input: 0.9V -4.2V^Good * The memory feature will memorize the last mode^Good * Ideal for flashlights using 1 x AA or single Li-Ion batteries (14500, 16340, 18650, 17670)^Good * Output current on 1 x Li-Ion: 1,000mA on high, 300mA on medium, and 60mA on low^Good * Output current on 1x AA alkaline or NIMH : 500mA on high, 200mA on medium, and 50mA with low mode^Good * Will signal when the voltage of Li-Ion is 3V and below (Blinking 3 times on low and medium mode). ^Good (if it can be disabled) * Boost circuit board ^Boost only? How does it regulate when input is 4.2V? * 15mm base board diameter^Good * Lead wires already soldered on board ^Good ** Due to the low voltage warning for Li-Ion, this driver is not ideal for lights using 2 x AA or single CR123A primary battery** ^Not so good!
So, it is a boost driver, but it blinks the LED when the voltage is below 3V. They have a good thing going here and then they goof up the UI. Hate to say it, but I have to pass on this one.
Well, aside from the LV warning, wonder what happens when Vs exceeds the Vf of the emitter. Im hoping it bucks, but looking at the driver, I've got my money on the fact that it doesn't... I would love to have someone who knows chime in here, Im very interested atm.
Ya see, that's what I get from staying up late reading these postings. I've been to the ShiningBeam website, and I've seen that very circuit board. It is in fact pretty much what I want. I guess that I was too tired to understand what I was reading.
Thanks for the reply, but what I was after is what the driver that was recommended does. The question essentially boiling down to, is this a Boost/Buck driver or a Boost only.
Anyone looked at buck/boost cct using the Maxim1703? It won't drive 3A but it will give a XM-L 1400-1500mA which is decent output from 2 AA/AAA NiMH or anyting up to 5.5V. It'll drive 600mA from a single NiMH...
So far there hasn't been much response. It's probably do to the fact that there are so few drivers of that size available to the public. I would love to see a reasonably priced 15mm driver made for members of BLF. Hope this idea takes off.
