LED Light Panel Build, Part 1

Ok, ok. This is finally the first post that even remotely relates to what the website is all about. However, I confess. This isn’t exactly a step-by-step build. More of a build that’s about 75% complete. But I’ll go through some of the steps on this build.

The main purpose of why I wanted to build 3 of these LED light panels was that it would be relatively cheap and provide the necessary lighting that I wanted to use for either photography or shooting video.  There’s a whopping 468 daylight white LEDs on each light panel! A brand new unit would cost around $500-$800, whereas the cost of each panel built is about 25%-30% of that!

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The LED array and wood box frame.

I drew inspiration from DIY Perks build (you can check out the Youtube video here). I picked up a few reels of daylight white LEDs (I’ll have links to the stuff I’ve implemented under a budget breakdown table in either Part 3 or Part 4). Since there are 468 LEDs, I had to use two reels to do a single panel (each reel comes with 300 LEDs on the strip). I decided to go with the cheapest jelly roll pan as a heatsink surface to apply the LEDs to, instead of applying it to a non-metallic backer. The jelly roll pans were unfortunately covered with a non-stick coating, so I had to rough up the surface with a cheap chisel to allow the LED strips and any adhesives to adhere better to the surface. If I had to do this over again, I would probably use an aluminum baking sheet that didn’t have a nonstick coating on it.

DSC_0087 (3)I epoxied blocks of wood onto the jelly roll pan to raise my flat tinned copper braids, off the surface, for my positive and negative terminal power bars. A bit crude, but it does the job. Before applying the LED strips down, I also made sure the ends of the LED strips would lay over some electrical tape, since I would be soldering the ends to my terminal bars. I didn’t want to risk a short by accidentally solder directly to the metal surface. That’s why you see the black electrical tape. Once the LED strips adhered in place onto the jelly roll pan, then came time to solder the respective points on the LED strips to the terminal bars. As you can see, the left side of the panel had all the positive connections, and the right side of the panel had the negative connections.

DSC_0085I used some 24AWG magnet wire to bridge the terminal bars to the LED strips. These are coated in enamel which burns/melts off quite easily with a soldering iron. Once this was done, I decided to make a wooden pine box frame to hold the jelly roll pan. I made a dado cut within the box to make space for the jelly roll pan to sit in. Nothing too fancy. I didn’t want to waste my time and effort hacking the jelly roll pan to fit in the pine box frame. I also made a second dado cut to allow a 1/8″ piece of plywood to sit right behind the jelly pan, just so it would be easier to attach the electronic components onto the surface easier.
I made some 45 degree mitered cuts on the plywood frame, to create the box. Instead of using splines (since I don’t have a real spline jig yet), I used some screws to hold the box together. For those that aren’t aware, mitered joints are weak, due to the joint being end-grain to end-grain. Woodworkers will use a wood-type joinery, instead of metal fasteners, as they’re more elegant and they don’t look awful.

The build quality of the wooden box frame doesn’t scream “fine woodworking.” I know. If I took the extra time to build a decent spline jig, this wouldn’t look so horrid with the screws showing. But the screws will be covered up with some wood putty and this will be painted, eventually.

I wanted to make the LED panel versatile. I wanted to add legs onto back of the panel so I can prop the light panel at an angle on the floor, to light up a background or whatnot. This is composed of a single block of wood with a carriage bolt through the top. I drilled a hole through each side of the back portion of the light panel, to accommodate the bolt through the panel. This would be held on tight with a 5-star plastic knob.

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DSC_0092-(2)I also wanted the ability to use this on a light stand, so I snagged a few brass Manfrotto threaded studs that would thread onto some t-nuts. I only needed to attach a stud to either the bottom (for the panel to sit horizontally) or one side (for the panel to sit vertically). So only two sides had the t-nuts installed. Again, nothing too crazy. Unfortunately, the Manfrotto threaded stud was longer than the thickness of the wood box frame, so I had to notch out one of the legs to make room for the threaded stud clearance. I could’ve ground down the Manfrotto stud, but I didn’t want to waste time grinding down several brass studs. Notching out the leg (as shown below) is way easier! Also note in the below picture, that I made sure the t-nuts would stay secure with some screws on both sides of it.

Oh, the reason why I had to recess the t-nut from the inside panel was because the dado that I cut in the pine wood, for the 1/8″ plywood, had clearance issues. So I decided to recess the t-nut with a Forstner bit on the good ol’ drill press.

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That was the bulk of the main panel build. A lot of planning was involved, trying to figure out how to make the cuts that I wanted, as well as the features that I wanted to add. This was definitely not a lightweight build by any means. The box alone was weighing in at under 10lbs. I would probably try my hand in some ultralight MDF next time. But the features that I had were well worth it. The ability to prop the light panel up on itself was a huge plus for me, as well as propping it onto a regular old lightstand with a tilt attachment (see picture below).

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The dimmer circuit.

DSC_0101 (2)To simplify the build, I went with some cheap electronic parts off of eBay and AliExpress. There are some people that complain about the Chinese DC-to-DC power converters, but I haven’t had any issues with them. There are very limited instructions/manuals out there on how to use these, so I can see the challenge for most folks trying to figure out how they work. I may consider doing a write-up to breakdown these power converters so that folks out there can spend less time tinkering and more time applying these to their projects.

The first part of the electronics that I wanted to get out of the way was the 12V dimmer circuit. Dimmers out on the market typically consist of a pulse-width modulating circuit, or PWM. The basics of a PWM is that there’s a duty cycle of an on and off “pulse”. Depending on how long the pulse-width of “on” time is, compared to the “off” time, will ultimately dictate your brightness level. There’s nothing wrong with a PWM dimming circuit, except they tend to show up on video footage as a pulsating/strobing lighting effect that can be undesirable.

Instead, I wanted to build a voltage-controlled dimming circuit, which starts off with a DC-to-DC power converter. The one I used was a DROK DC Buck Converter, which typically steps down voltages. This type of converter is great for LED strips in boats or cars, because they can protect the over-voltage when the engine’s on. Buck converters will typically step-down voltages, and step-up currents. This means an input of 1A @ 15V, can be converted to 1.25A @ 12V. DIY Perks does a great job of how to setup the DC buck converter for the dimming circuit.

As you can see in the picture above, I had to create some custom enclosures out of 1/8″ baltic birch plywood. Instead of waiting for your typical wood glue to dry, I sped up the glue process of the small custom plywood enclosure boxes with some cyanoacrylate glue, commonly called CA glue. There’s a ton of different brands out there, but I prefer the 2P-10 brand, as it was more convenient for me. There’s usually an activator spray and several “grades” of CA glue, ranging from a thin liquid to a gel-type glue. I prefer using the gel-type glue because you can reinforce the interior of these boxes with a thick gel bead, spray some activator over it, and it’ll yield a strong wood box enclosure. The cure time for CA glues is usually a minute; however, spraying a mating surface with the activator will yield a strong bond instantly.

Below, I’ve created a simplified PCB layout of the modifications that were made to the DROK DC-to-DC power converter. On the bottom of the power converter, I soldered a 6.8K resistor in series with a 22K potentiometer, parallel to the onboard trimmer potentiometer pins. This provided the dimmer circuit, to dim the lighting. On the top, I had to add an extra line from the input terminal block to wire the fan controller…I’ll get to why I had to use a fan on this circuit.

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Once I modified the buck converter, I plopped it into my small custom wood enclosures. I went with custom wood enclosures, instead of a readily available plastic enclosures, because of the clearance of the potentiometer knob. I wanted everything on the rear of the light panels to be relatively flush to the brim of the back side of light panels. This would allow me to stack these light panels on top of each other rather easily, and nothing would be sticking out and off the back side.

DSC_0098 (2)After I finished this circuit, I did a quick test with the LEDs and my 12V bench power supply. As noted by DIY Perks, the aluminum heat sink on one side would tend to heat up. This would worsen when you applied 15V to the input of the buck converter, and stepping down to 12V. So, to mitigate the issue, I decided to go with a centrifugal-type fan. They’re a bit pricier than your typical axial PC fan, but they can provide a ton of CFMs. They do tend to be noisy as well, so I had to use a fan controller to reduce the voltage being supplied to the fan.

I soldered the input of the fan controller to the input of the buck converter. But before connecting the output of the fan controller to the fan, I made sure that the small potentiometer, on the fan controller board, was turned down so that I didn’t supply the fan with a voltage greater than 12V. This is the potentiometer to control the fan speed, show in the image below. Since the fan itself was pretty powerful at 12V, but overbearingly loud, I stepped down the voltage to the fan to around 6-7V. I didn’t want to noise level of the fan to be too loud, especially if the light panels are being used in videography. This keeps the fan quiet, but still pushing a decent amount of air onto the one heatsink on the buck converter that tends to heat up.

Fan-Controller

A cheap plastic enclosure was used on the fan controller, just so I could stay consistent with keeping most of the electronic components covered and out of the way. Also, I used a sheet of automotive gasket material for the fan to sit on, which can be purchased at any automotive store. I figured that it would reduce the amount of vibrations being transmitted from the fan to the light panel.

If I were to do this part of the build all over again, I would prefer using a laser cutter or 3D printer to build a custom enclosure to house the buck converter, fan controller, and centrifugal fan in. There was some trial-and-error involved, but on future builds, I would definitely consider automating the build of the custom enclosures. Cutting each piece of plywood to the correct shape with a coping saw and hand saw is tedious and time-consuming.

So, is it worth it? Well, I did a quick test shot with two of the LED light panels. One light source was at mid-brightness, aiming down from above the subject. The second light panel was at 75% brightness and it was placed standing up, towards the front left, aiming at the subject. My faux table top is too narrow for this particular shot, but you get the idea. It’s amazing what good lighting can do to your photos!

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In Part 2, I’ll cover the battery pack system when using the light panels in remote locations where you don’t have access to AC power. One other thing I want to add to this build are some barn doors, so I can focus the light on a specific portion of a subject, and not flood an entire scene with light. Still contemplating a decent design for that!


Random Tip: Using Meat Grinders

I figure for the blog portion of the website, I’ll have random tips that may not interest everyone on the website. These are just great tips that I’ve picked up and tested. They’re not necessarily relevant with the website, but they’re nice to haves and may interest folks.

Grinding your own meats.

I purchase my chicken breasts in bulk. A local butcher tends to sell $1.20/lb to $1.30/lb for a 10lb bag of chicken. Unfortunately, they don’t have any ground chicken. Typically I’ll do some shredded chicken, by boiling a large batch of chicken breasts for approximately 2 hours. It tends to get old, and I’ve got a few recipes where I want to use some ground chicken. So, I decided to snag an electric meat grinder off Amazon. The bottom is a LEM meat grinder. From what I’ve read about meat grinders off many of the products on Amazon, consumers who tend to buy these machines, either electric or manual, tend to complain about the final ground product to be slow, sub-par, or the machine jams up.

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Fortunately, I’ve got a great tip from a friend that will help folks from ending up with buyer’s remorse! My friend Ben read somewhere that freezing your meats and the meat grinder for approximately 30 minutes will help yield a better grind. Which makes sense, since it’s harder for the machine to try and grind something blob-like vs something firmer. And ‘lo and behold. After tossing the grinding portion of the machine (not the electrical motor unit!), and cutting up pieces of chicken in small portions, the machine had zero jam ups and one happy customer!

But yeah, decided to jump on this because ground chicken around here is almost $4/lb, depending on where you go. After grinding 50lbs worth of meat, the machine pretty much pays itself off! Shavings? No, savings! (Sorry,…the damn GEICO ad is so obnoxious yet too memorable.)

So next time you’re going to get a go with grinding your own meats, remember to freeze the loading tray, the grinding blades you plan on using, and the meat grinding worm and housing assembly! I would highly recommend that you DO NOT freeze the electric motor assembly!


Harbor Freight Roller Cabinet Mod, Part 1

I snagged a 26″, 16 drawer glossy red roller cabinet combo (good ol’ U.S. General) from Harbor Freight the other day. This usually goes “on sale” for around $370, but if you look hard enough, you can find coupons to knock off $50-$75. My buddy Ryan linked me to a sweet HF coupon database (the Google is strong with that guy). So I managed to snag the combo cabinet for about $317. With tax, I ended up picking it up for around $334, which wasn’t too bad, considering the reviews that this cabinet gets.

Now, before I get lambasted because I bought something from Harbor Freight, let’s be perfectly clear. Harbor Freight doesn’t always have quality products. The same day that I purchased the tool chest combo, an older gentleman was giving the cashier a little trouble when he returned a 12V defroster. He raged a bit about how he ended up freezing in his car, while waiting over an hour trying to defrost his windshield to no avail. Yes, Harbor Freight does have garbage. But every once in a while, you’ll find some gems that are an excellent bang for the buck, that will either work flawless out of the box, or you’ll have to tinker with it to make it work beautifully. This 26″ tool cabinet combo is the latter.

The comparison.

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As you can see above, the US General (HF) cabinet, side-by-side with the Craftsman tool cabinet. Not much of a fair comparison, considering one is a the 16 drawer cabinet (HF) and the other is a 6 drawer cabinet (Craftsman). The differences between the two (aside from the slight chroma of the red paint, logos, handles, and wheels) are very noticeable. The Craftsman cabinet drawer slides very effortlessly and feels very light when opening and shutting the drawers, even when they’re packed to the brim full of tools. Whereas the HF cabinets are chunkier and heavier, which I actually don’t mind. It’s like comparing the chiclet-style keyboards on laptops vs the chunky 90’s IBM-esque keyboards. I like the refinement of the new, but the tactile feel of the old is oddly satisfying.

Mobility.

Imagine both chests were filled to the brim, weighing about 500-600lbs total. Moving the Craftsman chest is an effortless task. The roller bearings feel like they can handle any surface. Unfortunately, this is where the HF cabinet struggles. Other owners have notice the same issue where the wheels are sub-par, and there’s a SIGNIFICANT racking issue, which is quite noticeable when you’re opening and shutting the drawers (see this Youtube video on the issue, and how it was tackled by ghostses). When you take the drawers out of both cabinet and perform a quick inspection on how the casters are attached the box, you would think that the Craftsman was a bit lacking in securing the bolts.

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Oddly enough, that wasn’t the case. The Craftsman drawer showed very little signs of racking/swaying when opening/closing the drawers. Without doing some thorough investigation by measuring the thickness of the sheet metal on the bottom of the cart, or inspecting the welds between the floor pan and the body of the cabinets, my best guess is that the sheet metal on the floor pan of the HF cabinet is thinner and isn’t reinforced as well. This assumption is further strengthened when you inspect the 44″ cabinets that HF offers (one can do a quick Google image search of the bottoms of the 44″ cabinets). It appears that they reinforced the front to back with a solid piece of rectangular tubing, right above where the casters would sit. I guess the 26″ cabinets were not so lucky!

The future solution?

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After seeing what the Youtuber ghostses did with a piece of angle iron that reinforced the inside of the floor pan of the cabinets, I decided to go with some wide channel 6061 aluminum. I went with 6061 aluminum, specifically for its structural-type applications where rigidity matters. As you can see above, I’ve also decided to go with an upgrade on the caster wheels. The cheap roller bearings on the OEM HF casters weren’t cutting it for me. I could potentially see the stock casters ending up dragging along over time, and potentially be harder to move around when I decide to move the tool chest around. Stay tuned for updates on this project!


Why not?

So I found myself barreling into the new year with the yearn to finally scratch a personal goal off my list. I wanted to start a small blog detailing builds and ideas that I’ve culminated over the past few years.

Reflecting back.

Looking back, I’ve worked on a ton of projects, where some have been completed, and more than a handful were stuck in limbo. I’ll be honest…I do have this habit of putting projects on the back-burner because a full-time job and a social life do tend to get in the way. It’s a little harder with my current shop set-up, as it’s not as convenient as a basement or shed in the backyard. Nor is it heated in the winter. So the motivation during the winter seasons just isn’t there. But these are excuses that I’m giving myself, and it’s a new year!

Lesson One.

Stop making excuses for yourself. Bottom line is that it doesn’t have to be a new year’s resolution, or something you’ll put of until next week to get done. Get out there and do it! Whether it’s building a project, hitting the gym, or attending a network event. Never put things off. I’ll admit I’m a culprit at doing this, but putting in the effort is well worth it. And sometimes you’ll have to dig hard to get that self-motivation churning. Or maybe surround yourself with like-minded people where you can feed of each other’s motivations. If anything, this website is a good example of how I’ve put something off for too long, and I’ve finally decided…why not?

Just the tip.

Yep. Getting this website started is just the tip of the iceberg. Where did you think I was going with that? My goal here is to hopefully impart some of my technical background upon the masses. I am an electrical engineer, during the weekdays. So I’ll try to flex some intellect around here when I can. But the website is about mixing technology with raw media projects. The raw media will mostly be wood, but there may be some metal and composite-type projects that I’ll share as well. So, with that said…
…take it or leave it!