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RaceR86
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Great thread Rufusbduck!


About whining drivers and FETs. Its the main reason why im still on the sideline and seeing all the progress being made by knowledgeable people... I hope you guys finds the solution. I prefer my lights to not sound like there is something wrong with them..

Keep up the good work everyone!

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Tom E
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Talking to the EE's at work, they said the magic # is 20 kHz or higher - out of the human range.

comfychair
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Or lower, too. Lower frequency will be less likely to make parts this size move in a way that makes audible noise. Like if you take a poly done tweeter and send it a 200hz signal, it will move but not enough to make a noise you can hear.

RMM
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The fast PWM in STAR works well with the K4212... I accidentally did that when I was testing the momentary at first.  Forgot to switch it...the low modes just weren't nearly as low, high modes were the same.  Never tried it with the 70N02 but it may just work as well.

The inductor/etc. seems to definitely add a lot of squeal depending on the size and as Comfy has noted, the size of the capacitor.  The problem is that a large inductor + large capacitor = not enough room! 

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DB Custom
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I’m about to put my very 1st scratch built driver together. I’ve got the 17mm FET board, V1, and all the components. But now I can’t seem to locate what goes where and in which direction. This is pointed at which resistor is R1, and which direction does the diode go? Is the line on the diode the positive?

comfychair
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http://75.65.123.78/nanjg105c.jpg

For the diode, best to check the datasheet for the specific one you have. They don't all follow the same rules.

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Tom E wrote:

This is weird because I’ve been using luxdrv with phase-correct at 9.4 kHz for over a year and can’t seem to hear a whine in PWM modes at all, on all my builds – lots. Am I just not sensitive to it? Of course at my age, I can’t smell much or taste much either – I have to smother my meals in Habernero sauce so I can taste something at least, though it may be somewhat painful… Smile Got my 1,000 lumens EDC strapped to my head and drug store #3 glasses on just to get something done on the bench… It’s fun, Just you guys wait and see…

Pics or it didn’t happen Big Smile
RMM
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Tom, I'm still young and I need a headlamp strapped on and glasses as well.  My hearing is still good though! Tongue Out

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Tom E
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You really don't want to see this ... Can't believe I'm planning on playing softball again this year - first game this Sunday morn. These guys were begg'n me - dunno why, accept maybe for a few laughs as I stumble down to 1st base. Actually my reflex's are still pretty good - been playing ping pong and can still keep up with the quickness. I pitch, so reaction time is extremely important against these roid rage kids and their shaved bats...  (ooops, off topic). Well, bats that are high powered and mod'ed -- sounds familiar...

texaspyro
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Tom E wrote:
I can’t smell much

Sure you can… just don’t shower or change your underwear for a couple of weeks. You’ll be smellin’ big time in no time. J)

comfychair
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Welp, my old standby version of luxdrv doesn't work on the 17mm FET board (sometimes a half-press gives two mode changes instead of one, sometimes none at all), even though with the same components on a 105C PCB it works fine. I think I need a nap.

DB Custom
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Based on the components as they were on the Qlite. I wired it as it seemed best and the DMM shows power, but no light. I’m at a loss.

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texaspyro wrote:
Tom E wrote:
I can't smell much
Sure you can... just don't shower or change your underwear for a couple of weeks. You'll be smellin' big time in no time. J)

Only to others though Smile

"Based on the components as they were on the Qlite. I wired it as it seemed best and the DMM shows power, but no light. I’m at a loss."  which board?

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Matt’s first FET board, the one with no ground pads on the spring side.

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DBCstm wrote:
Matt's first FET board, the one with no ground pads on the spring side.

Can you post a photo of both sides and I can tell you if it's a hookup issue or if there is (I hope not) a potential trace issue?

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Mine acts like the early attempts when the code didn't work right without an added capacitor. Just weird, unpredictable mode changes. Sometimes it even does a strobe mode that's not there. Sometimes it does weird patterns of blinks like morse code. Checking the board with the meter, the cap is connected to where it should be.

http://75.65.123.78/Dsc07490.jpg

http://75.65.123.78/Dsc07489.jpg

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Check the Vcc voltage of the MCU to make sure the diode is not connected in reverse.

comfychair
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If the diode were backwards it wouldn't work at all.

The diode seems to be compatible with what comes on the 105C, I get 9 blinks in luxdrv's battmon mode from a cell that measures 3.87v, close enough for me.

Now that I think back, on the big 46mm version, mode changing went goofy as well when I was testing without the big 470uF cap. I'm using this one, should be correct right? Does it just need one rated higher than the 105C's original?

RMM
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Comfy, I think that capacitor is correct, I think I've seen mentioned that the stock cap is also 10uF.  This one should even be better since it's an X7R from a name brand... dunno what's going on there.  You could try and stack a second cap on top of that one to see if you get any better results.  

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DBCstm wrote:
Based on the components as they were on the Qlite. I wired it as it seemed best and the DMM shows power, but no light. I’m at a loss.

Pics of your build please?

Diode backward?

What OSHPark board are you building the 15,17, or SRK?

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Comfy…is that the 17DD initial release the one w/o the ground ring on the battery side..might not be getting a good ground (floating ground)

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WarHawk-AVG wrote:
Comfy...is that the one w/o the ground ring on the battery side..might not be getting a good ground (floating ground)

Looks to me like he's got a wire soldered directly to the FET pin for ground, is that correct?

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Ah…duh…bench test

Why did you go to a 10μF from a 470μF? Wouldn’t it be advisable to go higher rather than MUCH MUCH lower?

comfychair
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I have a separate ground wire stuck right onto the FET's ground pin, testing right now with a battery box with alligator clip leads but I'll be using a separate wire soldered to the inside of the pill, and rely on just a press fit to hold it in place, it's plenty tight like that if you don't completely file off the flashing.

comfychair
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I think I have a giant bag of 33uF 'A' case tantalum caps around here somewhere...

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WarHawk-AVG wrote:
Ah...duh...bench test Why did you go to a 10μF from a 470μF? Wouldn't it be advisable to go higher rather than MUCH MUCH lower?

Because he's using this one on a 17mm board where there isn't room for a huge electrolytic cap.  We know that it can function from the stock 105C cap., so it should be able to function here as well.  

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comfychair
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The 470uF/16v on the SRK driver is only for noise reduction, it shouldn't be needed for the MCU to function (but for some reason, it looks like it is letting the MCU work right, because the little 10uF/16v doesn't seem to be enough).

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Ah…and just did a SMD 0805 search on digikey..largest SMD is 47μF

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Well…that cap could be storing enough energy to keep the MCU alive at 470μF, opening up that huge MOSFET more than likely causes large voltage sag and drops the power below the MCU voltage range causing it to go all squiffy

comfychair
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But why does it work when you stick the same FET onto a 105C, using all the 105C's original parts? Is it possible the original cap isn't 10uF? There's nothing different about the new PCB, I've checked everything until I'm crosseyed.

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