Received my new red D4K the other day and have really enjoyed it. The sst20 4000K high cri is quite pleasing to my eye and the LumeX1 driver has a very low low. However, when using the lows my flashlight sings a high pitched whine that changes pitch when I ramp brightness and goes away completely when I ramp up bright enough. Anyone else have a singing D4K?
No noise in my D4K w/ 519a dd and Lume X1 driver.
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It’s probably the inductor that’s vibrating, it might be possible to dampen the noise by physically dampening the inductor on the driver. A thermal pad squished up against it or some thermal glue/potting compound poured on it or something might do the trick. This is if you’re comfortable removing the driver and messing around with it.
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I have two Fireflies with this driver. One of them whines quite loudly on low levels, another one is silent.
I think TheFreeman conducted many tests on his driver builds, when he encountered this problem and it was related to capacitors. I vaguely remember the reason being that the switching of the boost converter happened in a frequenzy that caused some resonance on the caps at certain chosen capacitances and certain output levels. Can’t recall exactly.
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Mine does this too but I can only hear it if I hold it to my ear.
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I can hear mine five feet away.
A lot of whining is caused by the inductor when it isn’t soldered tight/flush to the PCB.
If it is soldered tight it won’t whine. If it’s resting on its leads it won’t whine but can break away when falling.
Unless you have future plans to make serious changes to the electronics (on the PCB), I would suggest to cover the foot of the inductor with some kind of dampening material. My choice would be a few drops (or a little wall) of multi-purpose adhesive. Let it dry, repeat if necessary.
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