Eyebrow Lights

A high energy collision / accident / mishap in front of Adams Fairacre Farms (a.k.a., the grocery store) demolished 20 feet of their dry laid stone wall along Rt 44, flattened several bushes, gouged trenches in the grass, and scattered plastic debris into the parking lot. The remains of a headlight eyebrow running light emerged from a snow pile:

Eyebrow light - front
Eyebrow light – front

From the back:

Eyebrow light - back
Eyebrow light – back

Contrary to what I expected, it has one white LED at each end of the chromed reflecting channel, topped with a shaped plastic lens collecting the light:

Eyebrow light - Lens mount
Eyebrow light – Lens mount

The LED PCBs are in series, which produced a backwards wire color code on one end:

Eyebrow light - LED PCB 1
Eyebrow light – LED PCB 1

The other end looked more reasonable:

Eyebrow light - LED PCB 2
Eyebrow light – LED PCB 2

The white SMD LEDs draw 300+ mA at 3.6 V, so they’re obviously depending on external current limiting provided by the regulator PCB, sporting a TLE4242 linear current regulator and a handful of passives:

Eyebrow light - Regulator PCB
Eyebrow light – Regulator PCB

AFAICT, they didn’t use the chip’s PWM control input or its LED failure status output.

Extracting the various PCBs from the wreckage and reconnecting the wires produced a satisfactory result:

Eyebrow light - resurrection
Eyebrow light – resurrection

The regulator limits the LED current to 120 mA at any input from a bit over 7 V to well past 12 V, with each LED dropping 3.0 V.

Dunno what I’ll use this junk for, but at least I know a bit more about eyebrow lights. The chip date codes suggest 2010 and 2012; perhaps linear regulators have become passe by now.

7 thoughts on “Eyebrow Lights

  1. Why was this interesting item filed under Recumbent Bicycling? The words riding, bicycling, and recumbent are not found in the text. There are no photos of a bicycle. Nit pick, nit pick…

    Maybe the unspoken (unwritten) idea is that you will install an eyebrow light on your recumbent bicycle. A distinctive accessory that will make your bike stand out from the crowd of other ‘bents on the streets of DCNY!

    1. Obviously, the plan is to turn this into a longer series involving the recumbent bike, custom designed 3d printed parts, battery management, and bed-bugs. The ad-revenue from this new blog topic will generate enough income to buy a vacation home and to give up quilting and selling blankets to tourists.

    2. Ooops, I forgot a link to the running lights for the bikes: fixed!

      Edge-lighting the fairing would be even spiffier than an eyebrow light, although we’d have a hard time seeing around the glare. Maybe as an RPQ for our night-time parades?

  2. Tantris, you are on the right track. Weave in wild turkeys and the proper seasoning of cast iron cookware… and you have a sure winner!

  3. Most of the running lights I see on cars here are individual LEDs and on my weekly commute on the highway I find it annoying! Specially at disk.. Old eyes cant handle those sharp lights.

    1. Newer cars definitely use many more white LEDs, which probably means the per-LED cost has dropped by a factor of ten since 2010-ish, and they definitely produce more glare.

      I worried about glare when I built the bike running lights. Now, we’re just another pair of white LEDs.

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