DIY: Super Bright Flashlight Above 10k Lumens Costs Under $40
In this post I’m going to show you how to build a 10k lumens super bright LED flashlight. It’s designed to be operated with just one hand, with easy control of brightness, and can be powered by either batteries or an ac adapter. It has two modes, flood light mode and spot light mode, which makes it very useful for a variety of different situations.
As it’s such a bright light you can get some really interesting shots with it, whether you want to illuminate a scene to emulate moonlight, or add some drama, or raise the suspense with some UFO invasions…
For indoor shots it can be bounced off walls to act like a giant softbox, or used as a rim or hair light. The possibilities really are endless.
Non-photographic uses range from using it as a work light to help visibility while working, to just using it as a super bright portable floodlight rather than those puny little flashlights most of us have. Handy if you ever go camping!
This is going to be a long post, so grab a drink and let’s get going.
DIY Super Bright Flashlight: Install Voltage Regulator On Cooler
So the first thing we need for this build is obviously the LED itself. These LEDs are extremely bright, but they also get extremely hot. So to keep it cool we’ll be mounting it to a computer processor heatsink. These vary in size and shape depending on which you buy, but you should be able to adapt the design if you can’t find the one I used.
As the LED requires around 30v, we’ll be powering it with a voltage booster so that we can use lower voltage power sources, like batteries or laptop adapters.
As this voltage regulator will be handling a lot of power we need to enhance its cooling.
To do this, we could simply put a fan on top of it, which would make the build simpler.
This however would add more noise, so instead, what we’ll be doing is mounting it between the main heatsink’s heatpipes so that the voltage regulator can be cooled by the main heatsink instead.
As it’s a bit of a tight fit we need to re-arange some components. We’ll start by removing the regulator’s own small heatsinks. To do this we need to remove the screws holding them in place and melt the solder on the supports underneath, sing a screwdriver to pry them off the board.
Once they’re both removed we need to also detach the ICs they were screwed to. We can just rock them back and forth until they come free, but as they aren’t identical we’ll work on one at a time so that we don’t mix them up.
Once the first one’s off, we can get three short lengths of wire, around 6cm long, and use them to re-attach the IC, making sure that each pin gets connected to its original contact point. It’s literally just an extension. We need to repeat the process for the other IC as well.
As the capacitors are also a bit too tall, we can desolder them as well and, using some stiff wire to extend the contact points, mount them horizontally instead.
We need to keep the polarity same by connecting the pins marked by the striped edges to the sections marked with diagonal lines.
The regulator is now thin enough to slot in betweenthe heatpipes with plenty of room to spare.
Now it’s time to work on the dimmer controls. The first step is to remove the regulator’s trimmer potentiometer.
To do this, we need to add plenty of solder to the three pins underneath so that they join up, and pull the trimmer away from the board at the same time, being careful of any flying solder. Once the trimmer is disconnected, we can make sure that the pads on the bottom are no longer joined up by the extra solder that was added.
So now what we’re going to be doing is building this simple circuit, which is basically an adjustable resistance divider.
We’ll start with the actual brightness knob. So we need to get a 10k potentiometer and solder a coloured wire to its left most pin, with the shaft facing upwards. Now we can solder an 11k resistor to the middle pin, adding a black wire to the other end afterwards.
Next we can twist some additional wire lengths to the ends, keeping the colours the same for consistency. This leaves two exposed points to which we can solder to in a second.
Now we can get the trimmer potentiometer that was removed from the voltage regulator and again solder an 11k resistor to its middle pin.
Now we can solder the exposed section of the black wire to the other end of this resistor, and solder the exposed section of the green wire to the pin underneath the golden adjustment knob.
It’s now ready to be connected to the voltage regulator. So we’ll solder the green wire to innermost contact point where the trimmer pot used to be, and the black wire to the outermost point, ignoring the centre pin.
The next thing to do is extend the input and output connections using reasonably thick wire. An old mains cable is perfect for this. We need to take careful note of the polarity so we don’t accidentally connect it up the wrong way later. The polarity is written on the top of the PCB, but when looking at it from underneath, the two sets of pins on the left are the output set, which get connected to the LED later, and the two pins on the right are the input set, which will be hooked up to a power source.
The last thing to do is crimp an additional pair of wires to the input connectors. These are for adding a fan later.
So that’s pretty much it with the electronics. Now we can mount it to the heatsink.
So let’s slide it between the heatpipes and use a sharp object to mark the centre point of each of the screw holes in the aluminium fin below.
Now we can use a 2mm drill bit to drill through the fins at these points, using a screwdriver afterwards to push out the waste.
As we don’t want anything on the bottom of the voltage regulator to get shorted out when it’s mounted to the aluminium fin, we can cut out a piece of clear packaging plastic and again punch holes through it corresponding to the holes on the voltage regulator.
Now we can push some m2 (2mm) screws through the regulator into these holes, with a nylon spacers in-between. Once that’s done we can now screw it in place.
Before doing so we need to add the retention bracket that came with the heatsink as we won’t be able to add it later.
Now we can use some pliers to hold some m2 nuts in place and use them to firmly attach the voltage regulator. So that just leaves the ICs, which can now be mounted to the heatsink base using some heatsink plaster, which is essentially thermal glue.
We need to use a decent amount as the metal backs on the ICs does not want to make electrical contact with the heatsink base. We can clamp them in place and use a multimeter to check that the metal pads really are isolated from the aluminium they’re glued to. If all is well we can leave them to dry for around 10 hours.
After which we can remove clamp and again confirm that the metal pads are indeed isolated from the aluminium. Now we can hook the input wire up to a DC power source, and monitor the output wires with a multimeter. We have to make sure the main potentiometer is turned fully clockwise, and then adjust the trimmer potentiometer until the multimeter reports that the regulator is outputting exactly 30v.
Adjusting the main potentiometer should now slide the output voltage up and down between around 26v to 30v.
Before we start working on the frame we might as well sort out the power source for the fan. The power source is going to be a mini voltage step down regulator, which we can use do finely adjust the fan speed later.
So we need to take off the top fin of the heatsink, and drill two holes in it for the mini voltage regulator. Now we can screw it on with two nuts and two bolts, again using some packing plastic to prevent it from touching the fin.
The fin can then be mounted back on the heatsink and secured in place again with a small amount of superglue.
DIY Super Bright Flashlight: Metal Frame
Now it’s time to start on the metal frame.
To make it we’ll need four 60cm aluminum right angle lengths. The first thing to do is get one length and use a knife to mark its centre.
Now we need to make four marks – two 8cm from the centre, and the others 25.7cm from the centre.
Now we can use a right angle to score a V shape at each of these marks, with the point of the V meeting the central edge of the aluminium bar.
We can now cut out these v shapes using a hacksaw, smoothing the edges off afterwards using a file.
The next step is to position the heatsink’s mounting bracket at the center of the bar, but on the side without any v cutouts, and mark its hole points using something sharp.
We can then use an M3 bit to drill through at these points, making sure that we don’t drill into the table by using some scrap wood underneath.
In addition to the bracket holes we need to drill two holes on either side of the Vs, about 1cm out from their central points, again on the uncut side.
The last step is to drill a hole at each end of the bar about 1cm from the very end.
We need to do all this twice so that we have two identical bars.
Now we can get a spare piece of aluminium bar and use it to bend the v cuts against a table. We need to use plenty of pressure to make the bends as tight as possible.
Once they’re done they should look something like this.
Now we can cut a 16cm length off one of the spare bars and drill a 10mm hole in its centre for a quarter inch to 3/8 inch adapter screw to fit through, and use a 3/8 nut to bolt it in place, tightening it up with a penny.
This can now be screwed to the one of the frames using m3 nuts and bolts, forming the base.
Next we can cut out four 11cm uprights for the base, but before screwing them on we need to cut down the edges and then file them down so that they fit nicely inside the bends.
As you can see here, I already drilled a matching pair of holes in the uprights for the screws.
This was done using the same 3mm drill bit so that the screws can just go right through and get secured in place with m3 nuts.
The last step is to add some rubber feet, and that’s the base completed.
Now it’s time to work on the handle which attaches to the upper frame.
The first thing to do is make the supports for it, so what we need to do is get a 17cm length of aluminium bar and cut out a 90 degree v in its centre, and drill two m3 holes on the opposite side.
Lastly we can make two 130 degree cuts, both 1cm from either end. Using a clamp on the 1cm offshoot we can then bend up the bar so that it becomes parallel with the adjacent cut.
Now we can bend the v-cut and screw it to the upper frame. We need to make two of these supports, one for either side.
Now the supports are in place we can work on the handle itself. What we need to do for this is cut off another length of aluminium, this one 17.5cm long, and cut two large holes in it for the potentiometer and a power switch.
The diameters of both of these holes depend on the size of the components you choose, so use your own judgement here. The power switch I’ll be using is a high-current circular one, which required quite a wide 15mm hole.
Just like with the uprights, each end has to have its corner filed off for when it gets screwed to the supports.
To make the padded handle we need to get a dishcloth and roll one end up a few times to fill inside the aluminium bar and then wrap the rest of it the whole way around,using gaffa tape to hold it in place.
To make it look a bit neater, we can get a piece of false leather and fold it in on itself, with the underside of the material facing outwards. Now we can staple it together along the outer edge, and then invert it so that we’re left with a cylinder.
We can now fold over the edges and use some superglue to hold them in place. The whole thing can then be pulled over the padding and held firmly in place with cable ties.
Now we can add the switch, but before securing it in place we need to solder two thick wires to it. Again, an old mains cable is perfect for this.
Now we can add the switch and pull through the main potentiometer, securing it in place with its nut. The handle can now be screwed to the supports.
As you can see, I used some cable ties to hold the wires in place, and to secure the trimmer potentiometer so that it can be adjusted if needed.
So now we’re at the point where we can place the heatsink inside the bottom frame, and screw the upper frame to it, encasing the heatsink inside.
DIY Super Bright Flashlight: Install LED
Now we can finally add the LED, but before doing so we need to add a small strip of electrical tape on each side of the base. This is to prevent the LED’s contacts from accidentally touching the heatsink and shorting out. We won’t add any heat paste yet, but instead solder the voltage regulator’s output wires onto it.
It’s important that these are connected the right way around as the LED simply won’t light up if they aren’t. After the wires are soldered on we need to add some more electrical tape on top to protect against shorts.
Now it’s time to add the heatpaste to help thermal conductivity. So we need to lift up the LED and add a pea-sized amount to the centre of the base, and squash the LED back down on top. We don’t need to press it down much as that’ll be taken care of when we tighten up the brackets which we can now add.
The brackets may vary depending on what heatsink you use, but the process should be similar overall. Once they’re in place they can be very tightly screwed together, ensuring a secure mount and good thermal contact for the LED.
With the light now almost complete, there are only a few small jobs left. The first thing we can tackle is the power connection. For this all we need to do is connect a female XT60 connector to another length of thick wire, and then have the negative wire of this connect directly to the voltage regulator’s negative input wire.
The positive wire can be routed through the switch before connecting it up to the regulator’s positive input wire.
It’s important that you don’t get the polarity mixed up as it can damage the regulator and pop the capacitors if it gets hooked up the wrong way around, so double check before powering it on for the first time. We can also add a knob to the potentiometer at this point. So now we can try it out! All we need to do is hook it up to a power source capable of delivering at least 100w. An old laptop adapter is ideal for this, and it’s just a case of either making a little adapter with a male XT60 connector and a female round connector, or by chopping of the end and soldering the XT60 connector directly to it. We will be going over more power options, including batteries, in more detail in just a minute.
As it’s very bright be careful not to look at the LED directly. We mustn’t have it on full brightness for very long at the moment as we still need to add the fan to keep the heatsink cool.
DIY Super Bright Flashlight: Few More Steps
So what we can do first is solder the additional fan wire connectors to the mini regulator’s input, again being careful of the polarity.
Now we can mount the fan, but before soldering it to the mini regulator we need to power on the light again and turn the regulator’s trimmer potentiometer counter clockwise until its blue light goes off. This just means that we won’t fry the fan with too much voltage.
We can now solder the fan’s red and black wires to the mini regulator’s output, ignoring the yellow wire.
The mini regulator’s trimmer potentiometer can now be adjusted clockwise again until the fan starts spinning. We need to adjust it so that it keeps the LED cool whilst not making too much noise.
A good way to check whether the LED is cool is by simply touching its aluminium base. You should be able to keep your finger on it indefinitely even after 10 minutes of being on full power.
Don’t touch the front of the LED whilst it’s on as the light output itself can warm up your hand, giving you an inaccurate perception of how hot the LED really is.
As the heatsink is so large it’s possible to have the fan barely make any noise at all whilst keeping the temperature under control.
So, as this is a flashlight it’ll be pretty useful to have it run off batteries, so what we’ll work on now is the battery mount. The way this is done with elastic allows the light to be used with many different battery sizes and shapes, and it also allows you to strap on an ac adapter if needed.
So to make it we’ll get small aluminium sheet, just big enough to cover the back, and cut two groves in each side. I cut mine too close together; ideally they need to be the same distance apart as the height of the battery we’re planning on using.
After cutting them we can smooth them off with some sand paper.
Now we can drill four holes in the corners, corresponding to the spare holes on the back of the flashlight. We can also prepare an aluminium angle to act as a support for the battery. The fifth hole in the middle is to allow adjustment of the fan speed, as it goes through to the mini step down regulator.
To make the straps it’s just a case of getting some elastic and stapling them into loops, then slotting them into the groves and gluing them in place.
The whole panel can then be screwed to the back of the flashlight.
Lastly we can mount a battery low voltage alarm, so that we can avoid over discharging li-po or li-fe batteries, should we choose to use them. Although, if you’d rather have the battery disconnect itself automatically rather than just beeping, I have actually designed a circuit that can do just that.
The light can be powered by any source that has a voltage between 12v to 24v, so long as it can supply 100w. If you want to use an AC adapter, you can check its output wattage by multiplying its output voltage by its output current.
As for batteries, RC lipo or li-fe batteries are a good cheap option, and are readily available from webstores like obbyKing.
My particular battery didn’t come with the right connector, so it’s just a case of carefully soldering on a male XT60 connector, taking extra precautions against short circuits, as the battery can be killed if the wires touch.
Now that it’s wired up we can plug it in. Before we turn on the flashlight we can press the button on the voltage alarm to cycle through the trigger voltage. We can set it at 3.6v, as when lipo batteries hit this voltage they’re
more or less empty.
I found the beeper to be way too loud so I bunged up the horns with some blue tack.
Now we can try it out. As you can see, the light is incredibly bright. The throw is also quite wide, like a floodlight, which is handy for some situations but not when you need it to shine into the distance.
So, what we can do is make a removable lens to focus the light. To do this we’ll need a reflector and lens – both of these are designed specifically for the LED we used and aren’t very expensive.
The problem is that when the lens is put in front of the LED it brings the LED’s yellowish rim focus, which looks pretty ugly. So what we can do before fitting it is sand down the flat part of the glass element, using some water to help the process, until it becomes finely frosted.
Here’s what it looked like before.
And now after. Much better. Now we can get the reflector and file off the noggins on the bottom. Once they’re removed we can glue the lens to it.
To allow the lens to be removed we can tie some thin elastic into a loop and thread it over the heatsink’s bracket, and then insert the glass.
Now we can glue the elastic to the lens’s rim. This makes it easy to attach and remove, allowing you to quickly switch between flood light mode and spot light mode.
Anyone else think it’s looking like the ship from Flight of the Navigator? Anybody?
No? Just me then.
So that’s the light completed! As I mentioned earlier it’s useful for many different things, making it a very versatile light.