The Morse Riddler is a circuit I designed to be simple and cheap enough for kids and adults to use as a first soldering project, but powerful enough that they could have fun with it. In fifteen minutes, it can be soldered together and programmed to send riddles and their answers in Morse Code. Each press of the button will play one Morse Code message, which is either a new riddle or the answer to the last riddle. After a message, the chip goes into deep sleep to save power, not “waking” until the button is pressed again.


It’s a very basic circuit, just giving power from a coin cell battery to a microcontroller, and connecting the microcontroller to an LED and a piezo buzzer. The microcontroller is an Atmel ATtiny85 programmed using the Arduino development environment. A momentary switch grounds the reset pin when pressed. The firmware sends a message upon waking and then goes into low-power sleep.


It uses the following parts:

I designed the circuit boards myself, and had them manufactured by OSH Park. You can order more of them through the link above. Like the other links, though, I’m not making money from this, I’m just sharing my work and sources to help other folks make stuff.

You can find my code on GitHub. You will see the functions for making dots, dashes, spaces between letters, and spaces between words. The code also contains a bunch of power-saving stuff that might be scary to a beginner, but it’s just there to let the circuit sleep between riddles. I’ll keep tweaking the code for clarity and power consumption.

When doing the workshop with kids, I give them this handout to take home.

Happy Making!

Meditation strikes a special chord with me as a maker because it is said to foster creativity, intuition, imagination, and fantasy. I can’t think of traits better suited to making. I’ve tried meditation in the past, but it didn’t seem to stick. When I saw that NeuroSky’s Mindwave headsets had dropped to $100, I couldn’t resist trying meditation again, this time with feedback. These headsets measure electrical signals from your brain and determine two main metrics: attention and meditation. The charts and graphs in the headset’s app worked well enough for measuring attention, but the very nature of meditation is that you can’t focus on charts and graphs while doing it. I set out to build a more peaceful and serene visual output for my headset, one that would actually serve to calm me even further as it displayed the depth of my meditation.

Read more details at my post on Make Magazine site.

I’ve thoroughly enjoyed attending the last couple North Carolina Maker Faires. This year, I felt that I’ve finally built enough interesting gadgets to host an exhibit of my own. “The Creative Contraptions of Jeff Highsmith” will be a small table or two containing a few of my more interactive builds. The idea of the Faire is to engage visitors and inspire them to keep or start making fun stuff of their own. My projects are well-suited for this because they are original enough to be cool, but simple enough for most people to make, especially if they’re willing to learn a little.

I’ll borrow back my climbing game from the break room at REI.

Dispatchatron Senior has been in storage but will be ready with a little dusting and a few more toy fire trucks.

Dispatchatron Junior is always ready to travel, being smaller than a gallon of milk.

Additionally, I’ll have two more projects on display, a race track toy that I seriously enhanced and a scratch-built, multi-piece play set inspired by a Dr. Seuss book. These projects are complete, but I haven’t gotten the videos published yet.

I’ve also been working with a few fellows that are going to be launching a balloon into near-space from the parking lot of the Maker Faire. I’ve been writing code for the telemetry system while others are working on the other (harder) aspects.

The Faire will be awesome, I’m sure.

Post Zero

Greetings and salutations! My intent for this blog is to have a place to scrapbook my various and sundry projects. In the past, I’ve posted the kid-related projects to my sons’ blog and the rest to my Flickr photostream. Since I’ve been sitting on the jeffhighsmith.com domain for awhile, I decided to put it to use and have a consolidated spot for more technical descriptions of my contraptions.

Some of my favorite past projects include:

Web-controlled Car Launcher

Cigar Box Guitars

Peak 97 Climbing Arcade-Style Game

Teaching Gavin Orienteering

Reverse Geocache


Scaredy Squirrel’s Nut Tree


Lowrider Office Chair


Remote-Controlled Pumpkin Tractor

Popscicle Stick Helicopter

Unicycle Dump Truck

Cheerlights Tree

Construction Machine-Themed Tote Bags

Elf-Led Robot Making

Gavin’s First Robot Kit

Green-Powered Gingerbread House




Emboldened by the runaway success of my motobackhoecycle, I decided to expand my enterprise of impractical construction machines. I present the unicycle dump truck, a one-wheeled, self-balancing, load-carrying machine.


This box contains a microcontroller that keeps the box locked from the inside until its GPS sensor detects that the box is located at coordinates I can specify beforehand. Basically, I program the box for a certain location and lock a treat inside. I give the box to someone and they get to figure out what the box does and how to multilaterate the position the box “wants” to reach.
Most of the time, the box is in a very-low-power sleep mode. Pushing the doorbell button on the front wakes up the microcontroller and the box attempts to acquire a signal with it’s GPS receiver. Once the location is determined, the box runs some math to calculate the distance to it’s secret location. If the distance is within the threshhold (usually a tenth of a mile or so, depending on the location I pick), the box congratulates the recipient and unlocks its interior latch. If the distance is too far, the box replies with “Access Denied”, tells the recipient how many attempts they have remaining (after 20 button presses, the box locks permanently), and then displays the distance to the desired location. Eventually, the recipient should figure out that they should travel to different locations around town to push the button and draw some circles on a map to see where the distances intersect.
On the top of the exposed lid you see a magnetic child safety cabinet lock that I repurposed to use a backdoor in the event of a malfunction or a failure to locate the secret location. Down and to the left is an EM-406A GPS module from SparkFun Electronics. To the right is the 16×2 LCD that Adafruit sells for just $10. Moving to the bottom portion of the box, most of the wires lead to the Arduino Duemilanove board. To the right of that is a small circuit board that comprises the Pololu Power Switch that lets the Arduino disconnect its own power. Right some more you see the black Radio Shack battery case. I had to switch to a solidly enclosed version because the open type let the AA cells fall out too easily. On the left side of the bottom portion of the box I mounted a servo I had leftover from a Vex robot kit. The servo drives a latching mechanism I designed and built using sheets of PVC. The top lid latch engages the keeper on the bottom, unless a strong magnet disengages the lid latch or my servo slides the keeper to one side upon the solving of the puzzle.

When testing my reverse geocache, I found that it was rather tricky to solve, logistically speaking. I figured that the recipient of the box would simply grab a map, drive a fair distance, push the button, draw a circle of the radius specified by the box’s “Distance:” clue, and repeat until they had multilaterated the desired position. Simple, right? Turns out the trickiest part was drawing the circles. Even if you have a paper map that covers the area in question, you probably don’t have a compass that can draw a big enough circle. It isn’t any easier to do within Google Maps or Google earth. There are sites that will draw you one circle on Google Maps, but I could find none (as of December 2010) that would overlay multiple circles. So I wrote my own.
Please note that I made this only for the creator of the box to use in quickly and thoroughly testing the accuracy of the math. I did not write this page to lessen the challenge for recipients of reverse geocaches.