Desperatly looking for driver (updated kennan driver?)

[jtr1962]

Would a zener diode do that job?

It would in theory but it would have to be capable of absorbing the full LED current times the zener voltage. In other words, in theory yes, in practice no. A better solution is to feed back the output voltage via a resistor divider, and limit the duty cycle when it gets too high. Many step-up drivers have inputs for doing this.

[zega]

How bout this one?
http://cgi.ebay.com/3W-LED-Driver-fo...713.m153.l1262
In the menatime i have designed some discrete SMPS drivers (1 BJT and 1 MOSFET 1coil few res and caps) 90% eff in LTC cad in efficiency report (eff report is done wit a help of some tricks, cannot be done with discrete design), pricing of the parts is well under 1 $...
Ok i scrap coils from wasted PC PSU-s but it works great on small scale...
I have done 4,5W 54 10mm LED submersible LED drop in that work on 60V (boost) to drive 4x14LED in series in pulse mode and i am very satisfied with results!
I plan to work on that drivers a little more because they perform great for the price and lately i have fetish on simple as possible designs (no PWM controller or PIC used)...
z

[romroro]

Hello all, I have a question about Kennan drivers.
I received it from KD, it works fine ( approximately 1A Vin=7.4V Vout=3.5V)
But I would like put two in a parallel design for an hight current design.
But importunately it doesn't works ( it works but at 800 mA in place of 2000mA expected).

Is someone have design idea for do that works fine ?
Tks
Rom
PS: please excuse my bad English.

[TorchBoy]

Hello all, I have a question about Kennan drivers.
I received it from KD, it works fine ( approximately 1A Vin=7.4V Vout=3.5V)
But I would like put two in a parallel design for an hight current design.
But importunately it doesn't works ( it works but at 800 mA in place of 2000mA expected).

I don't know about using the Kennan in parallel, but I see that the datasheet for the PT4105 regulator chip (used in the Kennan) indicates that 1A current output should only be used with at least 9V in, and it doesn't recommend anything over 750mA output at any input voltage. Perhaps the Kennan isn't the best driver for the job?

[romroro]

Maybe you right, i'll look at effect with a bigger tension source ( 12 or 14 V ) and look at the result.

If someone one have an idea, i still looking for solutions.

[zzonbi]

I've got exactly the same driver as MikePL, after a similar delay too, but mine doesn't work nowhere near 1A, as I'd like, but around 700mA, creeping under 600mA as things heat up. I also noticed an annoying hiss, probably the inductor. Any suggestions for sollutions?

Be careful when connecting this board to a PSU over 12V as ringing may damage the IC. They skipped the RC snubber originally recommended. It's true this isn't required with batteries, though. But the long wiring in a car may be an issue.

OT: Is expecting an other free replacement realistic and do you guys get those packets at your door, or do you have to collect them from the post office?

[mike2g]

I recently got a few of the updated Kennan boards and am having trouble connecting to it. I followed the second diagram from MikePL's directions for (+) and (-) (which agrees with Jerry from KD). However my flashlight won't light up and I can't get any reading when disconnected on my multimeter. Poking around with the multimeter I found power as shown below. It seems that the negative contact is the same but the positive moved. From playing with the multimeter it seems as though the old positive is also negative (after positioning the positive probe as shown I moved the negative probe to the ? and got the same reading as when on the negative contact)

I know nothing about what the pieces on the board are doing but I know where the multimeter says that there's power. Is my board configured properly? Will the board operate as designed as I've made the the connection and if not what should I do?

just a little background, maybe relevant:

This board is connected to 6AA eneloops in a 2D maglite. I have a quad SSC (2 parallel, 2 series) setup. The emitters are H-bin so I was expecting each emitter to receive around 350-375ma at approximately 3-3.25V. (6-6.5V in series). My multimeter shows that the batteries are supply approximately 7.8V right now on the board contacts so I'm assuming that there is sufficient voltage for the board (at least 1.3V over what I need). As I've shown it the flashlight lights up but I am disappointed in the output. The brightness is comparable to a single SSC being driven by 4AA at 800ma this driver, which should be around 200 emitter lumens. I had expected the quad scc setup to be putting out approximately twice that, 400 lumens (350ma per emitter = ~100lumens X 4 emitters = ~400 lumens).

[R290]

So the extra IC would be for PWM dimming?

Why do some of these photos have a 22µH inductor and some a 47µH one? (I think those units are right.) I noticed that for the first version too. What difference does more than doubling the value of the inductor make?

I found this thread, as I too order these drivers for auto app.

The difference in the inductor has to do with the efficiency of the driver.
If you go to webbench you can select different efficiency ratings and see the values change. Another reason is size, and cost, less copper is cheaper.



From there web site

[uk_caver]

...This board is connected to 6AA eneloops in a 2D maglite. I have a quad SSC (2 parallel, 2 series) setup. The emitters are H-bin so I was expecting each emitter to receive around 350-375ma at approximately 3-3.25V. (6-6.5V in series). My multimeter shows that the batteries are supply approximately 7.8V right now on the board contacts so I'm assuming that there is sufficient voltage for the board (at least 1.3V over what I need). As I've shown it the flashlight lights up but I am disappointed in the output...

I'm not sure if there's quite enough headroom if the input voltage is 7.8V. At the very least, it'd be fairly borderline
I'd suggest trying to temporarily connect an extra cell or two into your setup and see if you get a brighter output.

[TorchBoy]

I'm not sure if there's quite enough headroom if the input voltage is 7.8V. At the very least, it'd be fairly borderline

KD's information said it needed 1V headroom for each LED being run, so the supply would need greater than 8.5V.

[zzonbi]

"Is my board configured properly?"

Your board is either a new design, either in error, as it has a condensor instead of a resistor (R5). I would resolder the led wires on the round pads, short circuit R6 and then try again.

What are these H bins SSCs?

[TorchBoy]

FYI "condensers" are normally called capacitors in English.

Capacitors are occasionally referred to as condensers. This is considered an antiquated term in English, but most other languages use an equivalent, like "Kondensator" in German, "condensador" in Spanish, or "Kondensa" in Japanese.

[zzonbi]

Hope you have the capacity to condense more English language (http://www.thefreedictionary.com/condenser), but thanks for trying to be "informative" ;-)

[spun]

in answer to mike2g i also have one of these new kennan's with what appears to be another of the capacitors in place of the old R5. well it works fine for me running two rebels in series. i read positive at both where you show positive in your pic as well as at the normal round positive pad that my led's are attached to. however i'm getting a 12v reading of my source at the pin you show and the proper 6+v for the rebels at the normal pad. make sure your soldering doesn't bridge the round positive pad to the smd part to the left of it. i've also had a couple of these drivers arrive doa.

[TorchBoy]

zzonbi - when synonyms are reasonably well known they aren't normally a problem, but the use of antiquated terms (in English, at least) may be a problem, for example because meanings change. I'm sure some people still like to use it, and it seems there are several non-English languages that still use a variant, but most people just won't understand what you're talking about, even if they know what a capacitor is. And I'd like to think that I did more than try to be informative - we now all know what you were talking about. QED.

[Brownstone]

Not only is "condenser" no longer used in English to designate a capacitor, electrical engineers have reused the word "condenser" to designate a device used to manage reactive load in power systems.

"Condenser" still exists as a fossilized word in "condenser microphone", but that no more means "condenser" is a current word for "capacitor" than the phrase "spick and span" means "spick" is a current word for "nails".

P.S. - I did understand you though. Just don't start talking about Leyden jars, animal electric fluid, and the aether.

[moonfish]

On motors, they are called condensers, as far as I know. But as far as the weird acronyms you guys use here that don't make sense, this seems trivial and a bit preachy.

[TorchBoy]

But as far as the weird acronyms you guys use here that don't make sense, ...

I've seen this angle before and I don't see the issue - I'm under the impression that forums and abbreviations go together, as it's a handy way to not have to type as much. You would do well to learn a few. (Whenever I see one I can't guess from context I look it up.)

... this seems trivial and a bit preachy.

And it's now off topic as well. If we all typed in our native language, understanding would drop considerably as there are a lot of people on CPF from non-English speaking countries. Your call on how important you think it is that we all understand what we mean by certain words. It doesn't need to be made into a big issue.

[zzonbi]

"because meanings change... people just won't understand"
QED
I like the last part. It hasn't changed much last thousands of years.

[TorchBoy]

"because meanings change... people just won't understand"

That quoting is a tad disingenuous. I said "people just won't understand" because they don't have a clue what a condenser was, which was a separate point from the meaning of words changing. But as I've said, people now know what a condenser was. Shall we get over it and move on?

[spun]

on a new(3 capacitor) kennan i've replaced the .2 ohm R1 sense resistor with .5 ohm and it's driving two rebels in series at 400ma now instead of the 950ma stock. at 12v in i'm measuring around 87% efficiency which fits the datasheet specs. my question is what wattage the .5 ohm resistor should be, i'm using two 1 ohm 1/4 watt resistors in parallel and they're not running hot at all.

second, a posting above has suggested modeling this circuit in webbench(webench.national.com) but the pt4105 is not a national semi part so is this possible? is there another modeling app for this circuit?

[jtr1962]

my question is what wattage the .5 ohm resistor should be, i'm using two 1 ohm 1/4 watt resistors in parallel and they're not running hot at all.

P = I²R = 0.4²*0.5 = 0.08 watts. This is about 1/12 of a watt. In other words, any resistor rated for 1/8 of a watt or more will suffice. 0805 size or larger should suffice.

[thides74]

I have just received some Kennans from Kaidomain. However, when measuring them, it seems that both output current and efficience is way off the specs.

Measuring the output current with a Cree Q5 I get 930ma and when measuring the efficience with a 3 x 18650 li-ion battery pack (Vin ~11,8 v) I only get an efficience of roughly 76%.

I have not done any kind of modification to the driver.

Can anybody confirm these results?

[TorchBoy]

Measuring the output current with a Cree Q5 I get 930ma and ... I only get an efficience of roughly 76%.

That's about right for the latest batch of Kennans. If you're handy with a soldering iron you can drop the output current and increase the efficiency.

[spun]

trying the pot dimmer mod from the datasheet, pretty easy and 0-960ma. tried the 10K pot but a 5K has better range. will add a resistor in line with a still smaller pot to limit the ma top and bottom. i use the 10uf cap + 1 ohm r across the input(datasheet and above) as i'm running 12v.

thanks jtr1962 for the help with my prior question.

[brighter-lights]

Received the new drivers a week ago and they are the worst I received yet.

The earliest version (old pcb) was perfect.

I ordered again and waited...I contacted kaidomain here and he said I must be patient we will get an improved version... but this improved version keeps shutting down from overheating until I added a heatsink...

This last version really sucks.

When running one Q5 from 3 cell lipo the board cuts out every 5 minutes or so.... thermal shutdown... It runs so hot you can't touch it.

12.56v battery (no load)
12.47v input (load)
Input current 380mA
Output current 890mA

When the voltage reach 11v with load, input current is 440mA.

It already had IC1 removed so I removed R5, R7 jumped R6 and put a .27ohm R2 in from an old board.... now it's much better... I can touch it...

Input voltage 12.56v (no load)
Input voltage (load) 12.50v
Input current 280mA
Output current 730mA

When the battery is empty at 10.5v the input current is 330mA

I'm trying the dimmer pot mod now.

Why do they manufacture these things if the old one obviously were so much better and more efficient?

[TorchBoy]

Why do they manufacture these things if the old one obviously were so much better and more efficient?

My guess is supply and demand. Enough people think that ~1A output is automatically better than ~750mA output that KD gets it made that way. I've even seen people on CPF basically demanding their 1A buck board. That the efficiency of the IC drops from >86% to <67% and the thing gets toasty hot as a direct consequence isn't a consideration for all these people at all, or that the difference in brightness isn't very great; they don't have a list of priorities.

Kai should know better though, and offer the old version as well, but perhaps he doesn't have a choice at a reasonable price, and he just has to accept what the manufacturer offers.

[brighter-lights]

As per the dimmer pot modification above:

Using the 100K across R2 and +
and a 1K2 (with R2 removed) gives me :

Input: 12.5v 290mA,
Output: 3.61v 780mA

Just what I want!

[saabluster]

provided I can get interest in 250 to 500 pieces.

You will have my support.

[ace0001a]

I've recently done a Quad Cree 3D Mag mod using 2 of these drivers in parallel running 2 emitters in series each and using a 9AA-to-3D battery adapter. I thermal epoxied the drivers IC side to the inside of the heatsink. So far it seems to run well. I've had the light on for as long as 20 minute stretches and it the light gets warm but not really hot. My Kennans are fairly recent and are of the newer design. Like the Sandwich Shoppe's Shark driver, I think the key is making sure you heatsink the driver well.