Imagine the ideal beach trip. The sun is shining, the skies are blue, the water is warm, and the humidity is low. You and your friends have everything you need to soak up the sun, sand and surf: a cooler filled with drinks and snacks, sunblock, flip flops, the coolest new swimwear, and the newest beach tech: the beach blanket/towel with corner pockets to fill with sand so it won't blow away; the sun shade with privacy screens and sand-fillable anchors for ultimate beach sheltering, even the spiked drink holders that keep your frosty beverages upright and sand-free.

But what's a summer day without a summer soundtrack? Good thing you've got your tunes on...your...very expensive...and very vulnerable to the elements...phone...hmm. Well, you do have that waterproof phone case with speakers, but it's bulky, ugly, and doesn't have a hole through which you could connect the little solar charging panel you bought (for when that fickle phone battery goes dead). Huh.

Well, while you're musing on what to do, don't forget the pain-relieving aloe gel in your cooler, for those inevitable sunburns. You're not keeping track of the time since you applied your sunscreen, admit it. You're just gonna burn. Might as well have the aspirin and Lidocaine easily accessible anyway. Enter the Beach Buddy. It's an all-in-one, water- and sand-resistant, solar charger, audio speaker system, and sunburn timer calculator.

This Instructable harnesses the power of Arduino, a UV sensor, and simple mathematics to make one nifty gadget sure to boost your outdoor summer fun - and minimize your indoor summer recovery!


For my Digital Multimedia class' final project, we were instructed to develop "a proposal for a new product, new iteration, a “masterful and well-crafted kluge”, etc. of technology and interface" in the categories of apparel/fashion, toys, tools, furnishings, and/or art.

My mind instantly flew to something having to do with sun protection, because of the horrible sunburn I suffered on the first day of class - even though I'd applied sunscreen before going to the beach that day.

What had happened? Had my sunscreen expired? Not at all - it wasn't as evenly applied as I'd thought, for one thing, but also I was in direct sun for far longer than my SPF was meant to be.

The World Health Organization has well-documented explanations for the UV Index, and the Skin Cancer Foundation goes into detail about both sunscreen sun protection factors (SPF) and the Fitzpatrick scale, a Harvard-developed system for classifying skin tones.

BUT WHAT DOES IT ALL MEAN?! And who has time for the WHO, the UV, the SCF, and the FPS?!

It all boils down to a simple formula. Once you know your Fitzpatrick scale type, you can calculate how long you can stay in the Sun without sunscreen before sunburn. Then divide that number by the current UV Index rating. Then multiply that quotient by your SPF rating - and your product is your allowed time in the sun before SPF reapplication is necessary.

So, in equation form: (Skin type time to burn ÷ UV Index) x SPF rating = time before reapplication of sunscreen.

The Beach Buddy does all this math for you with a few button pushes. Simply tell it your Skin Type and the SPF, and it'll read the UV index and spit out your timer calculation!

SO NOW, without further ado, let's get started on the Beach Buddy!

Step 1: Gather Materials

Note: the list below is rather exhaustive, and includes every last tool and supply I needed to make this project. Also note, my preferred supplier is Adafruit Industries, as it is a female-run company in a male-dominated field. Feel free to search for similar or equivalent products from alternate suppliers!

Materials - Project-Specific

  • 4x 10k ohm resistors
  • 10mm insulated standoffs (2 packs)
  • 2.1 mm DC Barrel plug > Alligator Clips
  • 9V Battery > 5.5mm/2.1mm plug
  • Acrylic sheet (thin)
  • Analog UV Light Sensor
  • 4x Breadboard-friendly momentary pushbuttons
  • Cable: 3.5mm Stereo Plug > Pigtail
  • 3x Cable: JST-PH Battery Extension
  • Enclosure
  • F/M jumper wires (1 pack)
  • LCD screen, 16x2 characters
  • 2x Lithium ion polymer battery – 3.7v 2500mAh
  • M2 screws, nuts, and washers (1 pack each)
  • M3 screws, nuts, and washers (1 pack each)
  • Mini adhesive-backed cable clips (1 pack)
  • MintyBoost Charger Kit
  • Nylon spacer (M2) (2 packs)
  • 4x Panel-mount momentary push buttons
  • PCB with connecting pads
  • Solar Charger Kit
  • Solar panel
  • 3x SPST Rocker Switch
  • Stereo Audio Amplifier
  • Stereo enclosed speaker set
  • Velcro strip
  • Wrapping wire (30AWG)
  • Optional: rub-on letters

Materials - Standard

  • 22AWG Wire, 3 colors each of stranded and solid
  • Breadboard
  • Cable Ties
  • Desoldering braid
  • Heat shrink tubing
  • Low-tack (painter's) tape
  • M/M jumper wires
  • Solder


  • Acrylic cutter
  • Arduino w/ USB cable
  • Calipers
  • Center punch
  • Cork-backed ruler
  • Dremel with cut-off-wheel attachment
  • Drill
  • Flush cutters
  • Glue gun with glue sticks
  • Heat gun
  • Needlenose pliers
  • Precision needle file set
  • Precision screwdriver set
  • File set
  • Soldering iron
  • Step drill bits
  • Tabletop vice
  • Third-helping-hand
  • Wire stripper

Download the attached .zip archive for the above list in 1) product-linked spreadsheet, 2) product-linked webpage, and 3) unlinked printable PDF form.

See it from germany, nice quality, perfekt Job and nice idea! maybe you took a Bluetooth Modul for the Audio input :D than it was perfekt!
<p>The best part of this is the sunburn timer calculator! I have to be very careful since skin cancer runs in my family, something like this would be very helpful!</p>
<p>That's the idea! I'm a licensed esthetician + a high risk as well, so I know the science, and have personally witnessed the effects of skin cancer. No bueno. Thanks for checking out my 'ible!</p>
It's a veey nice idea. perhaps you can build a version 2 with the tips bsims1 gave you! maybe i built one with that tips, i recently received a old set of pc speakers :)
<p>As a Ginger who had skincancer and is now tinkering with RE and Arduino this gets a big +1 and votes for both contests you are in. <br><br>Keep on tinkering on. </p>
<p>please marry me</p>
<p>This is a pretty cool project. If you find someone to help you with the code, then a voice message interrupting the music to tell you to apply sunscreen would really be cool. It also might be nice to have a UV index readout and temperature sensor.</p><p>Here are some more ideas... I think at the beach, the buttons would be better mounted to the top so you can bend down and press them without having to fumble around the sides with sandy paws to find them.</p><p>If you could fit all of the electronics in the top, that would be best. You can still cover them with the acrylic for protection, but the entire bottom could be used for cell phone and other stuff you don't want to get sandy. A flexible brush strip mounted around the opening could block sand and clean the phone as you slide it in.</p><p>It might be better to mount both speakers on the front so they would face forward. The wind at the beach is really noisy so it's hard to hear even louder speakers if they aren't pointed directly at you.</p><p>A light or two would be nice for those nights camping on the beach or anywhere else you might use the box.</p>
This is really really good! What a great idea and write up. super pics too :-)
<p>This is quality ! Excellent job.</p>
<p>Very cool project and well written. </p>
<p>O_O i can only say aweosome!!!</p>
<p>very cool!</p>
<p>So glad it turned out awesome! Great job, K. </p>
woohoo! feature! congrats K! :3

About This Instructable




Bio: starwisher is a shoe hater. A music breather. A cat lover. An ink bleeder. A (mostly) canon shipper. A yarn stasher. A super stanner. A ... More »
More by starwisher:Beach Buddy: 3-in-1 Solar Phone Charger, Boombox, and Sunburn Timer Calculator 
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