Wiring LED Chips

Supplies:

SMD LED Diode Light chips https://www.amazon.com/gp/product/B01CUGADNK/ref=p...

Soldering iron

Thin soldering wire

Liquid paste https://www.amazon.com/gp/product/B007Z82SHI/ref=p...

Thin cardboard or plastic for mounting chips

Magnet Wire (really perfect for this project) https://www.amazon.com/gp/product/B07H7FQTZM/ref=p...

Painters tape (to hold the chips while soldering)

Step Up Converter chip https://www.amazon.com/Eiechip-Voltage-Regulator-C...

Voltmeter

Tweezers

This project was designed specifically to light up a Cyclops Visor I made.

The goal: a thin narrow band of lights, with a compact battery source.

Disclaimer: I'm an amateur, most of what I have here is self-taught or gleaned from youtube. There are probably easier and/or better ways to do this, but it worked for me. Send me a message if you have any advice!

Quick backstory of what and why I didn't do something else:

First thought was LED light strips.

Pro: they're flexible, bright, and cheap.

Cons: the individual bulbs are spaced too far apart. If you want to the light strip to look solid, you need to add at least 3/4th of an inch space in front of it for a diffuser. Plus, it's only flexible one way (if you think X Y Z axis, flexible light strips are only flexible on the X axis, so curved paths are annoying. I could cut and splice a strip, but it's tricky and easy to mess up.) Conclusion: too rigid, lights not close enough

Second thought: LED Diodes. I spent a lot of time with these.

Pros: They're cheap and bright

Cons: they're big... well, big compared to LED SMD chips... more on that later...

Also, they're hard to solder, and you need to add a resistor to the light, also more on that later...

Last con, the light is focused into a directional beam, which looks weird, so even if the bulbs are right next to each other. So I'd still need a diffuser, adding more space in front of the bulb, which is already a quarter inch tall.

Conclusion: too bulky

LED chips are fairly easy to wire, in theory. They act just like old fashioned LED Diodes. Actually doing it is pretty hard. LED chips are super easy to burn out if you apply too much current. They're also super easy to melt when soldering. In all honesty, they're a real pain to work with; they're tiny, fragile, fickle things. So you've been warned...

The formula: R = ( Vs - ( Vl x n )) / I, where R = the correct resistance, Vs = Supply Voltage (your battery source), Vl = Voltage Drop (listed on the LED chip specs), n = number of LED's, and I = LED current (listed in LED specs). So I'm using a 9 volt source, the the Voltage drop on my LED chips are 2.2v, the current is 20 mili amps. Add it all up, and I'll need seven 10 ohm resistors, split into groups of 4 LED chips.

This website does the math for you:

http://led.linear1.org/led.wiz

Note: this is actually the easiest way I found to do it. If you just want to wire the whole thing in a line, you'd need a 62 volt source. Plus, one mistake, and you burn out all your chips at once. Breaking it into 4 chip groups is way easier to manage.

After some experiments, I decided on a 9v source (no you can't use a 9v battery, I tried, more on that later), and chains of 4 LED's per resistor (10 ohms for mine).

So I built about 7 separate 4-LED parts, with one 10 ohm resistor on the positive, and a thin wire tail on the negative lead (you can salvage the trimmed piece of wire from the resistor).

Put a piece of painters tape sticky side up, then tape down the edges. This gives you a tacky work surface to hold your chips in place while you work

Using tweezers, line up four LED chips UPSIDE DOWN, careful to match positive to negative, head to tail.

With a toothpick or small brush, put a small dot of flux on just the metal edges of the chips, as little as possible, just enough to coat the metal contacts.

Using hot iron and soldering wire, connect the four LEDs. Careful you don't melt the chips! Trim the wire ends attached to the resistor, the wires are super long, and you only need about a quarter to half an inch wire attached to resistor. Save the trimmings! I use them for the negative end...

Solder the resistor to the positive contact of the first LED, make sure it points straight up (going behind the chip, NOT to the side). Now use the trimmed resistor wire piece, and solder it the same way to the last LED, to the negative contact.

Turning 3.6 volts into 9 volts:

Time for the "Step up Converter Chip"! It can be set between 2v up to 24v (amazon links at the top), you can measure this with your voltmeter

First, before you attach the battery to the step converter, there's a little screw on it, rotate it with a screwdriver clockwise about fifteen times before using. Now you can measure the outputs with your voltmeter, turning the screw back counter clockwise until you get to 9v.

Quick tip: Disconnect the battery when you don't need it, the chip is easy to burn out if you cross your wires.

Another quick tip: When wiring up the step converter, use Magnet Wire for both input and output. The stiffness of the wire makes it harder to cross and short out.

For each LED group your made, touch the resistor end to the positive output and he negative wire to the negative output. It should light up instantly. If it doesn't, check your work: make sure chips are facing the right way, the solder isn't broken, the chips aren't melted, etc. If the something else happens, like smoke, or they flicker, chances are the chips are fried. I had to remake them several times. Better to find out now before you put it all together!

Now we need something to put the chips on. I actually 3d printed a curved chip holder, but in hindsight, I way over engineered this. In the future I'd probably use a thin bit of plastic (heat resistant plastic, like Kapton or Polyimide film). But I digress...

So choose what thing you're going to mount it to. If you can draw out or print out the thing first, even better. I used the images about as a guide. You'll need to poke holes in it for the resistor and negative wire to poke through to the back. I created some guides like these to help.

Before I glue the chips to the board, I glued a curved Magnet Wire on the top and bottom going all the way across I bent it carefully and smoothed it out to best fit the final shape, this helps keep it rigid. This will be soldered to the "Step up" chip we've calibrated already.

The magnet wire is our power for all the chips, so we'll need 9 volts going into the magnet wire. To get this, I used a 3.6v lithium ion battery (I bought these new, but you can salvage them from alot of sources) and using a "step up" chip to make it 9 volts.

Note: why a 9 volt battery won't work: Current! Each LED chip draws out 20 milliamps of power. This is complicated (for me at least) but a 9V battery is weak on current and doesn't have the amps to power that many chips.

Sorry I don't have a good pic of just the lights, I forgot to take one before I attached it to my project. You can see the resistor wire attached to the power magnet wire still.

So now I have two curved magnet wires attached to the step-up chip. Now I can solder on the 4-led chip groups I made earlier.

First, glue the chips to the board with the resisters and negative wire pointed out behind them. Make sure the LED groups DO NOT TOUCH EACHOTHER. The chip I chose has positive and negative contacts on the edge, if they touch another bank of chips, it'll short out.

Next, file / scrape / burn the parts of the magnet wire where the resistor wire and the negative wire will contact it. There's a thin insulation on the magnet wire, you need to remove that to get a good contact. Then solder the resister end to the positive magnet wire, and the wire tail to the negative.

If you did it right, they should all light up when you attach the battery. If one led doesn't light up, it probably shorted out and need replacing. If a group of four won't light, check the resistor and negative wire contacts, soldering can be tricky, and it may have broken contact.

Biggest problem you'll have: I don't know how to set up a real heat sink for the lights, so they heat up quickly. For my project that's ideal, but adapting it to another project that needs constant light, you'll probably want to find a way to do that.

And that's it! Is it a pain? Yes... is there an easier way? Probably... Does it look awesome? I think so!

I did this through trial and error, and made a bunch of things that didn't work. It was fun, frustrating, and thrilling. Send me comments if you like this or have a better info on how to improve it.