treasure hunt

2 Articles

Treasure Hunting With A Handful Of Common Components

November 15, 2021 by 16 Comments

Sometimes simpler is better — when you don’t need the the computational power of an onboard microcontroller, it’s often best to rely on a simple circuit to get the job done. With cheap Raspberry Pis and ESP32s all over the place, it can be easy to forget that many simpler projects can be completed without a single line of code (and with the ongoing chip shortage, it may be more important now than ever to remember that).

[mircemk] had the right idea when he built his simple induction-balance metal detector. It uses a couple of 555 timers, transistors, and passives to sense the presence of metallic objects via a coil of wire. He was able to detect a coin up to 15 cm away, and larger objects at 60cm — not bad for a pile of components you probably have in your bench’s spare parts drawer right now! The detector selectivity can be tuned by a couple of potentiometers, and in true metal detector fashion, it has a buzzer to loudly blare at you once it’s found something (along with a LED, in case the buzzer gets too annoying).

All in all, this metal detector looks like a terribly fun project — one perfectly suited to beginners and more seasoned hackers alike. It serves as a great reminder that not every project needs WiFi or an OLED display to be useful, but don’t let that stop you from overdoing things! If touchscreens are more your speed, [mircemk] has got you covered with a smartphone-integrated version as well.

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Navigation Thing: Four Days, Three Problems, And Fake Piezos

October 20, 2016 by 13 Comments

The “Navigation Thing“ was designed and built by [Jan Mrázek] as part of a night game activity for high school students during week-long seminar. A night-time path through a forest had stations with simple tasks, and the Navigation Thing used GPS, digital compass, a beeper, and a ring of RGB LEDs to provide a bit of “Wow factor” while guiding a group of students from one station to the next. The devices had a clear design direction:

“I wanted to build a device which a participant would find, insert batteries, and follow the beeping to find the next stop. Imagine the strong feeling of straying in the middle of the night in an unknown terrain far away from civilization trusting only a beeping thing you found. That was the feeling I wanted to achieve.”

The Navigation Things (there are six in total) guide users to fixed waypoints with GPS, a digital compass, and a ring of WS2812 LEDs — but the primary means of feedback to the user is a beeping that gets faster as you approach the destination. [Jan] had only four days to make all six units, which was doable. But as most of us know, delivering on a tight deadline is often less about doing the work you know about, and more about effectively handling the unexpected obstacles that inevitably pop up in the process.

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