It appears you have received the direct driver before with the E21A and that is why the LEDs burned, those 4pcs E21 cannot take direct drive.
This new driver should have the linear FET only working and have the direct drive FET disabled.
No
Compasses and mechanical watches are two of the only things I can think of that you really want to keep magnets away from anymore (and even then I’ve yet to magnetize or noticeably affect a mech watch by carrying any of my lights that has a magnet).
If I order a D4V2 with the KR4 driver how will that be different from the current D4V2 that I have?
Never mind, I have a better understanding now of what’s going on.
Is there a positive and negative side on the Olight UC charger?
NO. No polarity
Best to keep lights with magnets away from computers with hard disks as well. Sticking your light on the chassis of a computer like that is a no-no. Same principle as magnetically destroying data on floppy disks (or credit card strips!) back in the day.
SSDs (solid-state drives) and flash memory (like USB sticks and SD cards) are fine, though.
When it comes to flashlights, the one thing I can think of to watch is if you have a light with a magnetic control ring UI. My Sunwayman V20A behaves very strangely if another magnet gets too close to it. A powerful enough magnet could conceivably damage the little magnet in the control ring (and break the light) by permanently changing its direction of magnetisation.
Yeah, the magnet on a light can bugger up a credit card strip. Happened to me. Forgot I had a magnet on the light, and put a card in the same pocket, which I normally never do.
I got to watch my wife vanish down the subway entrance, while I tried to get get my subway pass card to work. After a few days she noticed I was MIA.
Mechanical hard drives are pretty tough. Don’t think a flashlight on the chassis of a desktop would bother one. After all, they have way stronger magnets inside the HD than found on a flashlight.
Dead HDs are a great source of magnets to play with. I have a file cabinet side decorated with a few dozen.
Don’t think it would be a good idea to stick a magnet on a laptop over the drive area. That’s a little too close for comfort.
As Phlogiston said, solid state devices won’t be bothered.
All the Best,
Jeff
It depends where you stick the flashlight. Most of the time, you’ll get away with it, because the magnetic field lines will pass through parts of the chassis metal without reaching the hard drive.
If you stick it to the hard drive rack inside the case, or to a chassis plate that comes in direct contact with that rack, then you’ll be pushing your luck, because the field path of least resistance may pass through the hard drive.
The magnets inside a hard drive are positioned very carefully and have metal elements near them to guide stray field lines away from the disk platters where the magnetised data bits are.
I must remember to salvage the magnets from my next dead hard drive 
I keep forgetting about the magnets and throwing them out!
I’m also collecting the platters out of my dead spinners, for a future art project. Most of my hard drive magnets are on my fridge…
What do these magnets look like?
I’m too lazy to take and upload a picture - but I checked, and the google image search result for “hard drive magnets” is pretty representative. I have varieties from both desktop (3.5”) and notebook (2.5”) hard drives.
The ones I grabbed look kinda like brake-pads.
Yep that’s exactly what they look like
Here are a couple. Often the holder has bends in it and makes it less handy to play with.
You can pry the magnets off the plates, but the magnets are way brittle and I often end up breaking one when doing this.
If you want a really strong magnet to play with, seek out an old 5.25” floppy drive - one of the early ones. They have a circular magnet that was used in the motor. So strong, it’s difficult to remove one from a fridge without divine intervention.
I’ve used the HD magnets to make clasps for woodworking projects. Good for holding “stuff” in place when a third hand is needed.
All the Best,
Jeff
Scallywag, I’ve also been collecting HD platters. I started when clients needed a data wipe on a drive that wouldn’t spin. Pulled the platters rather than smashing or drilling.
Not sure why I started putting the platters in a drawer after hitting then with the degausser, but there I go again collection “stuff”.
Some of the platters are more silver colored. They make great first surface mirrors as they are VERY flat.
For some reason I also stared stacking old CD disks from software releases Etc. Stuck a dowel in a hunk of wood and started piling them up. About 3’ tall by now.
For those interested in harvesting HD magnets, you will need a few smaller Torx drive screwdrivers. Be sure to look under labels for hidden fasteners.
Good quality stainless steel screws and aluminum (from the chassis) for recycling if you are so inclined.
All the Best,
Jeff
Yup. I have one of the $25 iFixit miniature screwdriver sets (well, it was $25 when I bought it, $35 here ) and it’s all I need for the screws. Some of the labels/stickers are a bit tough on just fingernails, so I’d recommend some kind of metallic spudger tool for those. As mentioned the magnets are quite strong so have fun with ferrous-metal tools occasionally snapping over to the magnets :+1:
The best platter I almost had showed significant head-crash damage. Along the inner half-inch the coating was mostly completely removed (some rings here and there remained). However, that platter technically belonged to an old employer and had to go to their secure data destruction procedures… (they drilled holes in the platters). My plan for my shiny platters is to mount them all in a frame as a cute artsy “mirror”.
That’s cool re: 5.25” floppy drives. I’m not old enough to have ever used one myself, though I’ve encountered them (and the actual floppy floppy disks) as scrap occasionally over the years.
salvaging magnets from old tech was something we did for several years.
now, we check out the recyclers on Craig’s List when we need some more.
regarding mirror-like platters: we used the hole as an aiming device
for signaling in Cub/Boy Scouts. it was harder to do as opposed to
using a dedicated signal mirror, but it can and was done.
fragility forbid inclusion in our load-outs.
Forgive my ignorance, it can be harm to the eyes look direct a Led driven by about 5 mA but with PWM?
the driver is AMC 4*7135.
A friend ask me if there will be eyes issues with PWM.
PWM itself will not harm eyes. However, if it’s slow enough, it can be unpleasant to see. Even disorienting, I think.
If the driver is 4*7135 the current should be 1400mA, so it’s unlikely to be 5mA unless there are 280 of such LEDs in parallel. I guess you mean 5W.