Create a model of a chemical structure using LEDs! Spice them up with 7-segment displays and you get a stunning sculpture!

Basically, you put together LEDs and 7-segment displays in such a way that models a chemical molecule. Each component represents an atom and everything is shaped such that it resembles the actual geometry of the molecule.

They make excellent gifts because they can be very personalized. You can choose a molecule that keenly describes the recipient of the gift, making it more special.

Step 1: Find Your Molecule

A good molecule should be quite complex and forms intricate structures. Really complex organic molecules work best.

Wikipedia is a good place to find molecules because they have pictures of the actual structure of the molecule as well as a brief description of its properties.

If you are giving this as a gift, choose a molecule that best describes the recepient. For example, the first molecule I made was acetylcholine which I gave to my friend Coline. The second one I did was phenethylamine, a substance dubbed as the "love chemical".

Here are some other suggested molecules
1) serotonin - antidepressant
2) tryptophan - makes you sleepy
3) dopamine - "rewards" and pleasure neurotransmitter

For this instructable we will be constructing the estradiol variant of estrogen, the female hormone

Step 2: Buy Your Parts

Your parts list would depend on the molecule you have chosen. What you want to do is designate a component for each atom in your molecule.

For most of the part, since you'll most probably be doing an organic molecule, carbon atoms will define the structure. Use an LED to represent carbon atoms. On a personal note, I tend to associate carbon with the color green, so I used green LEDs. Buy as much green LEDs as there are carbon atoms in your molecule

For the other elements present in your molecule, you may use a different colored LED, but i find it better to use a 7-segment display with the element symbol written on it (more on this later). Atoms such as oxygen and nitrogen are quite nicely represented by 7-segment displays.

Note also that hydrogen atoms are not explicitly represented in the sculpture. Why? Practicality. A typical organic molecule may contain up to 30 hydrogen atoms and that's too much. I find it best to include hydrogen only on those "special groups" like OH (hydroxide) and NH2/NH3 (amine). I tend to associate hydrogen with the color white so I used white LEDs (which are kinda expensive).

So for the estradiol project we'll be needing
18 green LEDs (for the 18 carbon atoms)
2 common anode (ELS402) seven-segment displays (for the 2 oxygen atoms)
2 small white LEDs (for the 2 hydrogens in the hydroxide (OH) group)

You'll also be needing a battery clip, 1kOhm resistor, soldering wire and iron. You might also want to buy an enclosure if you'll be giving this as a gift.

Step 3: Start Building Your Molecule: Carbon Backbone

Here's the technique I used to join together LEDs to form a benzene ring (the hexagonal part). You can use the same technique to create chains of LEDs at whatever shapes.

Take two LEDs and put them up together as shown in the first picture. You can have the LEDs form whatever angles, but since this would be part of the benzene ring, they are angled at 120 degrees. Squeezing their legs together like this fixes them in place so it'll be easy to solder them.

Note: be sure to solder together legs of the same length. What I mean is to solder them in such a way that they are parallel. For convention, I put the longer (positive) leg on top.
Also be careful not to let the solders touch, effectively shorting them out. Check if it works by applying voltage across the legs. All the components should light up.

Continue the process until you get the desired structure, stopping every so often to see if it still lights up. Next I'll show how to put the 7-segment display as well as share the technique I used on those "tricky" parts.

Step 4: Start Building Your Molecule: 7-segment Element

This step is tricky because you have to understand how 7-segment displays work.

On a common anode 7-segment display, you have 8 pins that correspond to the 8 "lights" (7 segments + 1 decimal point) and 2 supply pins (they are redundant).
1) Hook up the supply pins to a positive source
2) Connect the remaining pins to negative (ground) to light up the corresponding segment. See second picture for an illustration.

So if you were to write the letter O, You ground up all but the one pin that corresponds to the middle segment. If you were to write the letter F you ground up all the pins except the bottom and the two right side segments.

Here's the technique that I used to connect the 7-segment displays (refer to the first picture)
1) Bend the supply pins flat inward.
2) Insert a wire (perhaps a resistor or LED leg) through the bent pins and solder into place. (fourth picture)
3) Cut off the pins that you don't want to ground ground (the one that corresponds to the segment that you don't want to light up)
4) Bend the remaining pins together towards the center.
5) Place another wire this time on top of the remaining pins. Solder into place. (fourth picture)

You'll end up wit a 7-segment display with two wires sticking out of it. Connect this into your molecule as you would do with an LED. Be careful with the polarity!

Step 5: Start Building Your Molecule: Third Dimension

Most chemical structures are not planar. Some molecules have atoms that stick out in different directions.

To add an LED that sticks out, I find it best to bend the legs of the LED as shown in the first picture. Slot the LED into place in your molecule and you're good to go. You can use the same technique to attach LEDs at different angles. You can see the LED sticking out of the molecule on the third picture.

*NOTE: I have just realized that my model is not quite geometrically accurate. I should have been forming tetrahedrons on the second and third benzene rings. The technique outlined in this step could be used to make those tetrahedral shapes.

Step 6: Add the Finishing Touches

1) Solder on the battery clip
-Take note of polarity: Solder the red wire to the positive side of your molecule. Black wire goes to the ground side. NOTE: You should put the resistor between the molecule and the red positive wire to prevent burning out your LEDs. I actually forgot to do this, but it's still going to be pretty safe since you got a lot of LEDs in parallel sharing the current.

2) (optional) Put it inside an enclosure. The enclosure that I got has a screw-on lid. It's a nice touch to have the recipient of the gift use a screwdriver to "unwrap" the gift

Note that I didn't put any batteries with it. I also did not tell her what it actually is. She had to figure out that she needs to clip in a battery, and she had to do some research as well (she actually mentioned the Merck Index).

As a cherry on top, I've asked HER to take a picture of the sculpture all lit up. I'll post it here after she does.

EDIT: see the last picture with it all lit up!
In eightth grade we had a project to show the structure of the allotropes of carbon, graphite and diamond. Had I seen this then, lol Nice
execellent idea, but would definitely need a resistor. a 9V batt in parallel to those LEDs would definitely exceed the LED's rating. they'd heat up and die sooner or later. but i especially love the phenylethylamine idea though. nice present for someone you'd be courting or someone you like but wouldn't actually want to tell her so you have to make her guess, eh? hmmm. gave me an idea. he he he.:D
i'm quite impressed about the phenylethylamine idea myself. and that's exactly what i did. i let her guess what it is. about the resistor: I kinda forgot about that eh? I bought some but forgot to put them in
oh, then was she able to figure it out? he he he.:D update: okay. so i made one the other day and gave it this girl. she just loved it... BUT she couldn't figure it out. It's driving her nuts. He he he.:D By the way, I modified the circuit by adding a switch, a 1K resistor and an IC timer for blinking effects. He he he.:D
oh yeah she figured it out in a heartbeat. she's majoring in biology so there :)<br/>at first she said <em>&quot;do i have to use the merck index for this?&quot;</em><br/>then she mentioned &quot;<em>is this a cholesterol?&quot;</em> she noticed the four rings<br/>then she got a lot more closer <em>&quot;human steroid...&quot;</em><br/>then finally <em>&quot;estradiol!&quot;</em><br/><br/>and knowing that someone actually used my idea made this instructable all worth it... even though i didn't win the laser cutter lol<br/>
eh? i'm confused. she guessed estradiol? i thought it was phenylethylamine you gave? oh 711. number on my plate. lol.:D i don't know. i seem to be going nuts over LEDs these days.i've been putting them virtually everywhere, well except in my food. lol:D
the last one I gave was estradiol, the one on the instructable. the person whom i gave phenethylamine did not have a clue either :p
does she at least have an idea that it's a chemical compound? then try <a rel="nofollow" href="http://www.emolecules.com">this</a><br/><br/>if she still can't figure it out, tell her it's &quot;phenethylamine&quot; and it's up to her to figure out its characteristics.<br/><br/>good luck!<br/><br/>ps: is your birthday on july 11?<br/>
in addition to resistor you would need to hook them up in parallel, not series or the first will die thereby opening the circuit
you mean hook up the LEDs in parallel? I suppose they already are connected in parallel. check out the third step
oops. I missed that. Nice ...
What an excellent idea! It's a shame that molecular model convention has carbon as a black sphere.<br/><br/>You could make a <a rel="nofollow" href="https://www.instructables.com/id/E9D2ZJ3FG0EP286JEJ/">throwie</a> version of a water molecule - connect two small white LEDs at an angle of 120degrees, add a blue with the LED right at the junction and the electrodes sticking out to connect to the button cell.<br/><br/>Oh, and I'd love to see an image of the working circuit as well.<br/>
working circuit... hmm you mean with the battery connected? Unfortunately, I forgot to bring a battery when I was about to give it. Tell you what... I'll ask my friend to take a picture of the sculpture after she figures out that she needs to attach a battery to make it work :)
I'd take a bettery round <em>before</em> she adds her own - that clip is begging for a 9V battery, which could make things go <strong>pop</strong> too quickly to get the picture.<br/>
Shouldnt water be two white and one red in the shape of a hidden mickie?? (Micky mouse's ears and head)
Yeah, but blue and white is more ... watery. You could stick a load together and call them "ice".
ohhhh I get you now... hahah your right
Neat idea! I want to see a picture of it all lit up.
Sorry about that. I kinda forgot to bring a battery when I was taking the last minute pictures. I'll ask my friend to take a picture after she figures out what she needs to do, then I'll post it :)

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