Soft start your flashlight for longer bulb life

[Reinhard] has a great collection of DIY SCUBA projects. One interesting hack he put together is a soft start circuit to improve the life of the bulb in a flashlight. Despite LEDs getting cheaper, MR16 halogens are dirt cheap and put out some serious lumens.


  1. rm -rf *zoink* says:

    yes, zoinks, there’s a flippin’ schematic. happy now?

  2. tekunogekai says:

    What a bright idea.

  3. One could probably just use an NTC (negative temperature coefficient) thermistor. Some are actually sold as inrush current limiters.

  4. Rad says:

    I doubt this would make a diffrence with leds, so too bad I bought 200 10,000mcd diodes…

    Either way, hackaday hasn’t been living up to its name, I keep seeing more than one hack posted occasionally.

    And I couldn’t be happier.

  5. aaron says:

    there’s your photo effect to those of you who’ve taken notice when it’s not there :P

  6. japroach says:

    NTC would work, you can get one that will go from say 14 ohms down to 0.1 ohm, with a max current rating of 5A.

    The two downsides are: the 0.1 ohm on resistance is more power loss compared to the 0.04 ohm of his mosfet (although the rest of his circuit will take some power).

    and that if you switch it off, then on quickly, the inrush limit effect is weakened, as the thing is still hot.

  7. The photo effect! :0

    It’s just not the same hackaday without.

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