Kid ski helmet led light

Hello,

I would like to add LED lights to my childrens ski helmets. Basic idea is to have two small "antennas" (or Mickey Mouse ears or whatever shape they choose), two LEDs on each. Red LEDs directed backwards, white LEDs directed forward. Purpose of LEDs would not be to light up the slope ahead, just to make children happy, so they can see each other during night skiing and to get attention from other skiers on slope as a safety measure. Quick sketches:

Aside from mechanical construction I am more considering the eletrical part. Vision in my mind:

  • CR2032 battery/batteries(?) for pair of "antennas" (they are small)
  • Operation mode: flashing (1 Hz, 5 Hz) (maybe solid/fade-in/out/other patterns in advanced version)
  • Two individual channels: front LED pair and back LED pair (maybe four individual LEDs in advanced version)
  • Minimum working temperature: -15 deg C
  • Turn on/off switch, mode toggle switch
  • Expected battery life: 50 - 100 hours (solid mode)
  • Weight: as low as possible

Microcontroller would be nice to handle all that operation modes easily but one 3V battery would not be enough. One 3V battery with 555 chip and voltage booster or joule thief circuit could work for flashing mode for white LEDs as well. What about 3 AAA recharchables (nice capacity, relatively small)? ... No problem to change specs, I just do not want my children to wear heavy battery packs on their helmets. For safety, no wires from helmet leading under the jacket...

Which way would you go? Any comment appreciated. Thanks

Visit you local bicycle shop. I'm sure they'll be able to supply miniature front and rear lED lights off the peg (as worn by cyclists - not the bike.

CR2032 will not last long, just 225mAH capacity
http://www.dipmicro.com/store/BAT-CR2032
Look at something like 1000mAH LiPo instead

Micro running at lower frequency, 8 MHz or lower, will run fine from 3V.

Or use LEDs with the built in flash ICs

Built in flash will not support "solid/fade-in/out/other patterns in advanced version" tho.

CrossRoads: Built in flash will not support "solid/fade-in/out/other patterns in advanced version" tho.

Indeed not.... I'm thinking "entry level version" 8)

Have you identified LEDs that will actually be visible on the slope? In my experience children tend to be taught in well-lit conditions and milliwatt LEDs would surely not be bright enough to be noticed.

A bicycle front light with LEDs desoldered and moved to "antennas" is one of possibilities - cheap, waterproof housing, included battery holder, limited functions. I am just going through the options list.

What about ATtiny45/85?

  • two PWM outputs allowing to have separated front and rear LED group
  • possibility to program any fade in/out effect or flashing sequence
  • 8 MHz running from 2.7 V
  • 3 x 1.2 V AAA rechargables can provide 3.6 V
  • 3 analog inputs; for mode toggle button

LED power - I have seen couple of kids with a common bicycle red rear flasher attached to helmets, no issue with visibility. My kids already ski after sunset without "light helmets", so this would be a funny accessory, surprise. Anyway, this should be a fun project, no a lightning one.

Thanks so far for your ideas. Please carry on ;)

I’d be inclined to go with a light bar off an ambo, myself; like my son’s “company car” attached

Look at something like 1000mAH LiPo instead

You can probably get some “slightly used” ones from Boeing…

Doc1.jpg

If your using 4 LED's running approx 15mA each then you'll be looking at about 16 to 18 hours from 3 AAA batteries when fully on. I'd deffo look into using an ATTiny45/85 for this project as they are much smaller than the arduino atmega chip (same size as the 555 chip) and they have there own in built crystal (less circuit to build). I've just used the ATTiny85 for a similar LED project utilising the PWM output and creating various flash patterns, easy to program using your Arduino as the ISP.

Maybe thinking of using a rechargable Li-ion battery like a 14500. The're the same size as an AA battery with upto 1200mAh ratings (don't go for higher ratings as sold on ebay, they don't exist) but crucially they already output nominal 3.7v so one battery would be enough.

I forgot to post the image. Kids were happy. It is modified bicycle rear LED flasher. Two red LEDs at back, two organge LEDs at front. Worked in -10 deg. C.

The safety of crash helmets is dependent on the structure not being altered - adding anything on the top that could catch against a hard object sounds very dodgy to me, instantly splitting the protective shell... Also I can't see how you can attach without weakening it - glues are out (polycarbonate is utterly weakened by many solvents), and drilling holes is obviously a no-no.

Tying something soft on seems the only safe method.

If it wasn't for the glue/solvent issue LED strips would be attractive - perhaps these could be tied on rather than stuck on?

a easy solution to lighted ski helmet is to attach a headlamp to the back of the helmet with zip ties to whatever is available. No glues needed. Then you got AAA batteries so it will last a long time. They are cheap at most hardware stores.