ruffles' handbuilt diy contest monstrosity -- DONE! (Whew!)

Lotsa pics to follow (mostly of burned parts and wounds, I suspect), but here's a start.

This DIY build is supposed to be an area floodlight, driven by Dewalt 18 volt (19.2 when fully charged) powertool batteries.

Since I've got 5 Nichia 219 emitters and some sinkpads (thanks Nitro!) kicking around, I thought those could be the base. I'm sure I'll have fun learning how to combine the two.

Now, I'm frankly embarrassed that my electrical knowledge is so poor, but I figure asking questions is the way to learn. So my first Q: can I direct drive 5 Nichias in series with 19.2v? (reading the datasheet, the vf seems to be between 3 and 3.5v) The math seems to suggest 6, and I can always get more from IS, but I'm sorta hoping that the 5 I have can work. Does direct drive possibly push more current than the nichias can deal with?

If I'm totally off track and I need a buck driver and to run the leds in parallel, any suggestions? Efficiency isn't that big a concern, as I've got lots of batteries and lots of housing to drain heat with.

Thanks in advance!

A few photos of some of the stuff that’s gonna get victimized for this build… (not to sound like Stalin’s apologist, but you’ve gotta break some eggs to make an omelette)

So, a little bit of threaded aluminum:

A busted charger, and a soon to be plundered tripod:

Some resistors (thanks, Ohaya; I feel like I’m actually learning something here) and switches:

More random stuff: emitters, sinkpads, lexan (perspex for some), aluminum that I’m not looking forward to cutting by hand:

Last but not least, that little bit of threaded aluminum with a little something for size reference:

(Although my inner cheapskate resented having to buy that, I feel like it might be the best 12 bucks ever.)

Thanks again to Ohaya for the excellent resistor math below… it was super helpful.

So, I got started messing with stuff yesterday… here’s a few pics and comments.

One very long 1.5” x 1.5” bar of aluminum. Sadly, the wrong length, and since we’re in hand-tool-only land, I have a very sore tricep in exchange for 14 minutes of hacksaw work.

Putting a hole in the end. Glad we could use cordless drills.

1/4-20 threaded insert… I was too lazy (and didn’t have the right size tap) to do otherwise.

Banged in with a bunch of JB Weld at the bottom.

So that short-ish hunk of aluminum will take 5 Nichia emitters and tir-type optics. To hold them in place, I figured some plexiglass on the front would work well. (Otherwise, it’d be a gooey mess of silicone, and that didn’t seem quite right.) I had some crazy box section aluminum that I thought I could cut a couple of bits off of to make a glorified L-bracket. Like so:

I made a fancy miter box so I could once again tire myself out cut nice miters.

Only problem was, it was way too time consuming to try break it apart without destroying the L-bracket that I wanted. I spent some time trying to cut a groove in each bit that needed to come off and then clamping the #$%@ out of it, but that just plain didn’t work.

Back to the metal dealer… you’ll have to visit again to see what transpired.


Well, the contest is drawing to a close, and I was pretty sure I wasn’t gonna make the cut. However, here’s how it came out.

The earlier idea with the aluminum section really didn’t work, so I found some copper that I figured could work as a spacer between the lexan and the hunk of aluminum.

A little bit of work (okay, a h$%# of a lot!) involved in making nice miters.

Clamped up and ready to cook with the old butane torch.

But wait — what was I thinking? Clamping copper onto a massive heatsink and then trying to sweat it was not going to work. So plan B: do them one at a time.

So with that done, I could enjoy a little hand tapping action in the hunk of aluminum housing the emitters.

Oh carp! Broken hand tap. (And if you’ve ever tried drilling those out, you know that’s a non-starter.) I considered a few options (including giving up entirely and getting drunk), but in the end, flipped the darn thing over and started again.

Done! (The red that you see is silicone baking sheet, smooth both sides, to give me an extra couple of millimeters height.)

Ready to reflow some Nichia 219s onto Nitro’s sinkpads. This was my first time and the contest end was looming, so I was a bit nervous. Thanks to some good advice from here about solder paste, everything went smoothly. (I particularly loved how the emitter would suck itself perfectly into place when everything melted.)

The top one was my first, and you can see I used a little too much paste… the rest turned out nicer.

So, a couple of round bits of plywood for the top and the bottom… I couldn’t find my coping saw, so cut straight and whacked away at them with a chisel for a bit. Very satisfying and slightly time-consuming.

The item formerly known as ‘broken Dewalt charger’ is now chopped up, and its circuit board depopulated.

Top of the charger stuck onto the plywood, which is in turn stuck into the mega aluminum coupler. (Actually, I don’t really know what to call that thing. Maybe just BFAT.) There’s a judco switch stuck on the corner of the charger. The innocent tripod mount has been grafted onto the front of the BFAT, and there’s a magicshine cable for power connection in place. (This allows an extension cable…)

Jump ahead to a whole bunch of soldering being done…

This is direct drive, with 7 parallel 22 ohm, 1 watt resistors draining a bit of power. I could go into the math that I butchered from ohaya (thanks again!), but I’d only embarrass myself.

Oooh, money shot!

More posing!

Lexan on the front still needs trimming, but it wouldn’t be ramshackle if I did everything at once, right?

It lights!

Wall shot from a few feet away. I’ll try and do something late tonight, but wanted to get this all mostly up.

And one last shot. Did I mention that it actually lights up? (You experienced modders get this all the time, but it’s still surprising to me.)

So, many thanks to O-L for this contest. I grumbled, I griped. I cursed having to do metalwork by hand. And I enjoyed every bit of it. (Okay, maybe not the broken hand tap…)

Yeah, use 5 leds… we like flaming burnouts around here! J) 6 would be a lot better if you don’t, but 19.2V is in that area where 5 is too few and 6 too many for a direct drive light.

I’d love to help but I’d be leading you up the garden path.

To direct-drive 5 emitters in series with a 19.2V battery, you could use a current-limiting resistor in series:

- Assume 3V per emitter, so that’d be 3x5, or 15V.

  • So, you need something in series with those that will take a drop of 19.2-15=4.2V.

The Nichia data sheet says “Maximum Forward” current is 1.5 amps, so you want to limit current through the series and the resistor to 1.5 amps.

So, for the current limiting resistor, you want value of R=V/I = 4.2V / 1.5 amps, or 2.8 ohms, or thereabouts.

Since you’ll be putting 1.5 amps through the resistor, power = V * I = 4.2 * 1.5 = 6.3 watts.

So, ideally, you’re going to need a 2.8 ohm resistor that can take 7 watts (rounded up from 6.3) in series with the 5 Nichia emitters, and then you’d be good to go, running them at 1.5 amps.

I don’t know (haven’t looked) if you can get a 2.8 ohm/7 watt resistor off-the shelf, but you maybe get 7 - 1 watt , “X” ohm, resistors instead and put the 7 resistors in parallel (you need to figure out what “X” is). Note that resistors of the same ohmage are usually larger for larger wattage.


Edit: BTW, those resistors might get warm, so you may need to do something to help them throw off the heat.

Edit2: 7 1 watt resistors in parallel would give you an equivalent of a 2.8xx ohm/7 watt resistor

e.g., 7 of these in parallel: 20 Ohm 1 Watt Resistor

Edit3: Better yet

Thanks for the info! I’ll head to Fry’s (electronics supply, for those not in the US) this afternoon and grab a bundle of resistors.

I’m also toying with the idea of a proper driver from… we’ll have to see.


If you do direct drive with resistors, keep in mind that the calculations above are “ideal”, i.e., they don’t take into account an already-existant resistances like the switch, the body, etc., so, assuming that there are such resistances, and how large they are, if you use the “theoretical” calculations, you’d end up under-driving the LEDs relative to their maximums. From an engineering standpoint, that’s a good thing, but from a hobbyist, or your standpoint, you may want to/prefer to over-drive the LEDs :), so adjust the values as you see fit.


… now I actually have to build something with them, right?

With the size reference picture, you now have Foy's full attention.


Since a 219 on a well heatsinked sinkpad appear to give maximum output at about 4.3V (and survive 4.7V) I see no problem at all in just going direct drive here with this setup with just 3.8V max per emitter.

3V per might be a little under powered for this fugly monster. 8) Adding another(or more) resistor(s) in parallel will increase the current a bit with each added resistor.

….just in case??? lol. :open_mouth:

holy cow, that’s not a “little” bit of threaded aluminium, unless that drill pack happens to be one of Ken’s toy batteries!

as for cutting that solid bar of aluminium, good luck :slight_smile: I spent about 30min cutting through a bar a bit thinner than that with a jigsaw and metal blade, I shudder to think how long it would have taken by hand.

I put on my man shirt and my man pants. I cursed. I moaned. 14 minutes and one very sore tricep later, I was through. Now I have to make a miter box to cut these @#$! channel bits. (At least the channel will go quick.)

Quick edit: making the miter box was way too time consuming. And the channel went quick but was a complete fail for a few reasons that I’ll detail in the build section above. Back to the metal store…

your man pants must have more space for swinging pendulums as that’s bloody quick. Then again, B&D probably didn’t envisage some muppet cutting through 1x2in alu bar with their jigsaw :slight_smile:

Mentioning “man shirt” and “man pants” from a user whose name is “ruffles” just seems a little odd :)… Sorry, I couldn’t help it :)!!

I know it’s supposed to be portable but this is shaping up to be a shoulder fired fugly monster. Keep it going, I love it! :open_mouth:

That’s for when the flux capacitor goes critical — duh!

Anyway, updated pics+chatter in post 3… enjoy.

Fair dinkum. I’m sure OL did not realize what he would create when he was in the bowels off his shed smoking whatever dreaming up this comp. You guys doing the hand tools build all have one thing happening to you that is common through all the builds. Your all going to have arms on you like Arnold Schwarzenegger. Maybe when this comps over we could have another comp to see who has the biggest biceps off you all. Keep it up guys. I don’t think there will be any machine builds happening as you have put us all to shame.