Petzl Zoom Headlamp Upgrade: Part I

By now you may have realized that my blog has turned into a series of reports on what I do on weekends and holidays. This is because most (though not all) of the noteworthy events in my life occur during these periods. For a while in the summer I was pretty lax with reporting about anything at all, but I am now working hard at getting caught up again in case anyone still bothers to read this, and I will try to keep it up to date (though if it isn't up to date rest assured that it usually means I am too busy having fun to do so).

Anyways, nothing particular was planned for the current weekend in question, mostly due to an odious weather forecast that called for rain everywhere within a 6 hour drive of Seattle. Stinker! So, as Roanne had plans to head up to Vancouver for some wedding dress shopping with Mer, I decided to stick around Seattle and get some of the home improvements done that I have been postponing during the summer months when the weather was too good for it.

As you may have inferred from the title of this post, sometimes the best laid plans of mice and men go awry and as it turned out I did not do one single act of home improvement (much to Roanne's disappointment when she arrived home Sunday night). I did, however, spend a lot of time working on upgrading my old Petzl Zoom incandescent headlamp to high-output LEDs.

I'll spend another post on this after I have finished building up the design and have everything working as intended, but here is the short version of what I plan on doing: the general model of the Petzl headlamp I am upgrading is pictured below, it has a battery pack (designed to house a non-rechargeable primary cell) that is situated on the back of the head, and an incandescent light source up front which is turned on by rotating the outer bezel with further rotation of the bezel adjusting the beam focus. What I plan to do is remove the "guts" of the headlamp, replacing the disposable battery with a rechargeable Lithium Polymer cell (very high energy density, these are what are found in portable electronics like cell phones, etc.) and replacing the incandescent light source with an array of 4 high-output LEDs.The big advantage of this change is that it will be lighter (the Li-Po battery will weigh less than the disposable that it is replacing) and the LEDs will be stinkin' bright. By way of comparison, Petzl currently markets a high-end LED headlamp that is intended for caving which costs $430 and puts out 350 lumens, the 4-LED array that I am using will put out over 750 lumens under full power. Further upgrades to the headlamp functionality include in-situ battery charging (the battery will not need to be removed and will be charged by plugging an AC/DC wall adapter into the headlamp) and a continuously variable light output (the light output will be continuously varied between 100 and 750 lumens by turning a knob if you want less light output and longer battery life).

What I spent the weekend on was choosing parts to use for the electronics and designing a printed circuit board (PCB) that they will be mounted on. I sent the PCB out to be fabricated on Sunday afternoon, so it should be back in a week or two and I can start assembling the new headlamp and see if it works. I ordered some extra parts and PCBs, so if you have an old Petzl Zoom headlamp sitting around that you want turned into a real barn-burner then get your orders in!