Solarforce drop in produces sound

mousemouse said:

Hi Guys,

Just a background, I bought a new Surefire Centurion some time ago and it came with 2 cr123 primaries with an expiry date of 2018. With the incan p60 module it functioned as it should. However, with a single mode 3.7-8.4v Solarforce xml drop in, it produces an audible "whistle" when turned on. One thing I did to be able to use the drop in was to remove the big outer spring which did not allow the complete closing of the Centurion's head. I tried using 3.0v Soshine rcr123s and there was no sound. Any ideas as to why there is a sound? Would using this be safe?

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texas cop said:

It's the whine cause by pulse width modulation (PWM) yes from the inductor whine or also called coil whine. A few ways to get it reduced. Inject epoxy into the holes around the dropin, usually two of them when the reflector is taken off the pill. It's the holes the wires come through to connect the driver to the led. Put an o-ring sandwiched the reflector and the lens. Wrap foil around the dropin's brass base until its snug in the host. Make sure the reflector is tight with the pill.

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mousemouse said:

@everyone- thanks for the replies. Any ideas as to why it only happens with the primaries and the particular single mode drop in? I tried the combination on a Solarforce host and replaced the outer spring and it still buzzed. I used 18650 (on the solarforce host) and rcr123 (on the surefire host) and didnt get the buzzing. I also tried switching another 3 mode solarforce host and didnt get buzzing with the primaries.

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WalkIntoTheLight said:

Could be inductor whine. Might be a slight difference in voltage changes the resonant frequency so the coil stops vibrating and producing noise, or changes the frequency to something you can't hear.

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