Articulated Dimmable LED Bar Lamp

prusaprinters

This is a lamp that consists of a bar of LEDs, multiple articulated arms, and a base. The base has a swivel joint. Each arm has lockable joints. The LED bar has a tilt swivel joint.The default configuration is, from bottom to top, base, a plain arm (with hex nut recesses), a controller arm, and an LED bar. However, you can conceivably chain together several arms to make a custom configuration. One caveat on this: each joint must have at least one arm end with a recess to accommodate a hex nut (see the “elbow-bar-*-hex.stl” files. Also, there's nothing stopping you from doing a mix-and-match on the arm lengths. The “large”, “medium” and “small” folders contain LED bars and arms of lengths that are approximately 300mm, 250mm and 200mm respectively. The “small” pieces will easily fit on a Prusa Mk3 build plate. The “medium” ones will fit if you rotate them. The “large” ones would require a larger printer.Note: In addition to 3D-printing, you'll need to be comfortable with Arduino programming, basic electronics, and soldering. And, while this lamp runs off relatively low voltage, it is possible for a short circuit or an incorrectly-wired component to cause it to overheat, potentially melting or setting fire to the lamp. If you're not comfortable with this risk, please don't build this.PrintingAll parts are designed to be printed in the default orientation without supports. I printed everything in PLA at 0.2mm layer height, except for the lens, which was printed in transparent PETG. It wouldn't hurt to use something a bit more durable than PLA for the main pieces. ABS or ASA might work.For the default configuration, you'll need to print:1 LED holder (e.g. led-holder-16.stl)1 LED lens (e.g. led-lens-16.stl)1 LED back (e.g. led-back-16.stl)1 LED bar elbow (led-bar-elbow.stl)1 controller arm (e.g. controller-bar-200.stl)1 controller cover (controller-cover.stl)1 arm with hex nut recesses (e.g. elbow-bar-200-hex.stl)3 elbow knobs (elbow-knob.stl)1 table clamp (table-clamp-30.stl)1 base elbow mount (elbow-mount.stl)1 base mounting ring (mount-ring.stl)1 clamp bolt (clamp-bolt.stl)ElectronicsThe controller consists of an Adafruit Trinket M0 MCU, a power MOSFET, and two 6mm tactile switches. Note: If you don't care about dimming capability, you can skip the controller and power the LED bar directly from a 6V DC power source.Non-Printable Parts List10mm white LEDs (as many as will fit in the LED bar you print)680Ω resistors (one for each LED)M3 × 25mm cap-head bolts (one for each elbow joint)M3 nuts (two per bolt)Adafruit Trinket M0Power MOSFET6mm tactile switches (5.5mm height)Lots of hookup wire (22AWG)either heat-shrink tubing or electrical tapeA 5.5mm × 2.5mm power jackA 6V DC power supplyNote: The LEDs listed here aren't particularly bright. They're just what I had available. You should be able to substitute any 10mm LEDS and still have this work, provided you don't overload the power supply or MOSFET.AssemblyAssembly is, frankly, a bit of a pain. I designed this thing on-the-fly, paying more attention to ease of printing than ease of assembly. Let's start with the LED bar…The LED bar consists of a lens, an LED holder and a back cover. Insert the LEDs into the holder from behind (the side opposite where the lens snaps on), taking care to orient all the LEDs so that the negative (short) lead are all on the same side.Note: The red and black wires used here should be at least long enough to thread through to halfway along the controller bar. When in doubt, overestimate. You can always trim them back later.Solder all the negative leads together and solder to a black wire at the swivel end of the bar. Solder one end of a 680Ω resistor to each of the positive leads. Solder the other end of these resistors together and solder that to a red wire at the swivel end. Feed the red and black wires through the hole in the back of the holder, then out through the hole in the middle of the swivel. (Did I mention this thing's a pain to assemble?)At this point, you can test the LED bar by supplying 6V DC to the wires. Verify all LEDS light up and that you have no loose connections or shorts. If all looks good, you can snap on the lens and back cover. You can also snap the LED bar elbow onto the swivel. The elbow has a hex nut recess. You can insert a nut into that now, if you'd like.Next, let's tackle the controller. Do a quick test fit of the Trinket (aka MCU), switches and MOSFET. The buttons are a very snug fit, mainly because they need to hold up to mechanical pressure when you're adjusting the brightness.Remove the components and program the Trinket using the bar-lamp.ino code. Note: At this point, I tested the dimmer electronics using a breadboard and a single LED to represent the LED bar. You don't have to do this, but it doesn't hurt.Holding down the “up” button should cause the LEDs to gradually brighten.The wiring of these components goes like this:Trinket pin “Bat" to a red wire (this will eventually go to a 6V supply + )Trinket pin “Gnd” to a black wire (this will eventually go to a 6V supply - )Trinket pin “0” to MOSFET pin 1 (on the right side of the image below, yellow wire)Trinket pin “2” to one side of each switchTrinket pin “3” to the other side of the “up” switch (upper one in the image below)Trinket pin “4” to the other side of the “down” switch (lower one in the image below)MOSFET pin 3 (on the left side in the image below) to a black wire (this will eventually go to a 6V supply - )MOSFET pin 2 (middle pin) to a wire colored anything but red or black (I used blue; this will eventually go to the black wire from the LED bar)I insulated the middle pin on the MOSFET with a piece of heat-shrink tubing to avoid short circuits.Additional info on the Trinket M0 pinout can be found here. It's probably a good idea to keep that handy while wiring things up.At this point, I tested the circuit again using a breadboard and a single LED, just to make sure.A minor tangent at this point... You're going to need an elbow knob for to connect each arm to the next. The images of the knobs didn't come out well, but assembly is basically just pushing a bolt through the knob and tightening a hex nut into the recess on the opposite side. These then get pushed through each half of an elbow joint, and tighten into another hex nut on the opposite side. Here's a fairly blurry picture of an assembled knob. Now, back to assembly… Thread the red and black wires from the LED bar into the controller bar. Attach the black wire to the blue wire from the MOSFET, making sure the connection is well insulated (e.g. heat-shrink tubing or electrical tape).Cut two very long pieces of wire: red and black. These need to be long enough to snake through the arms leading to the base. Feed these into the controller box.You should now have 3 unconnected red wires in the box: from the Trinket, from the LED bar and from the base (the very long wire). Connect them all together and insulate the connection.There should also be 3 unconnected black wires: from the Trinket, from the MOSFET and from the base. Connect them all together and insulate the connection.You can connect the LED bar and the controller bar together using an elbow knob. Take care not to crush the wires while doing so. They need to move freely.At this point, I did another test, hooking up the long wires to 6V DC and verifying I could turn on the LEDS. If everything looks good, you can snap the cover on the controller box. Assuming you're doing the default configuration, you can now feed the long wires through the remaining arm from the controller bar, and attach the two arms together with an elbow knob.Now, onto the base…Feed the wires from the power jack through the hole in the side of the base (table clamp) and push the jack into place.Screw the elbow mount onto the base, attaching it with the mount ring. Feed the wires through the hole in the elbow mount.Trim the wires from the power jack and the remaining free arm end as short as possible but still leaving enough length to connect them.Connect and insulate each pair of wires.Now, push the wires back through the hole in the elbow mount so that the insulated connections are inside the base. (I did say this was a pain to assemble, didn't I?) No, seriously, this step elicited the greatest amount of swearing from me.Connect the arm and mounting elbow using the last remaining elbow knob. Screw the clamp knob into the bottom of the base.At this point, the whole thing should be assembled. Mount the lamp onto a table, plug in the power supply, and hold down the + button on the controller to ramp up the brightness on the LEDs.