A No-Calibration Metal Detector

July 17, 2022 by Jenny List 12 Comments

A traditional early project for someone discovering a love for electronics has been for many years a metal detector. This would mean a few transistors back in the day, but today it’s more likely to involve a microcontroller. [Mircemk] has an example that bends both worlds, with a single transistor oscillator and an Arduino.

This type of metal detector has a large search coil which forms part of the tuned circuit in an oscillator. As a piece of metal enters its range the frequency of oscillation changes. In the old days, this would have been detected as an audible beat frequency with another oscillator. This design would require a calibration step at the start of detecting, to tune the two oscillators to the same frequency.

This detector keeps the first oscillator but eschews the second one in favor of an Arduino. The microcontroller acts as a frequency counter, monitoring the frequency and issuing an alarm when it detects a change likely to be caused by a piece of metal. It may not have some of the finess a human ear could apply to a beat frequency in the all-analogue days, but it’s simple enough to build and it avoids the need for calibration. Seeing it in the video below the break we’re sure that just like those transistor models old, there will be plenty of fun to be had with it.

An Arduino may be one of the current go-to parts, but will it ever displace the 555? Perhaps not in the world of metal detectors!

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You’re The Only One Not Playing With Unity

June 21, 2017 by Will Sweatman 41 Comments

It wasn’t too long ago that one could conjecture that most hackers are not avid video game players. We spend most of our free time taking things apart, tinkering with microcontrollers and reading the latest [Jenny List] article on Hackaday.com. When we do think of video games, our neurons generally fire in the direction of emulating a console on a single board computer, such as a Raspberry Pi or a Beaglebone. Or even emulating the actual console processor on an FPGA. Rarely do we venture off into 3D programs meant to make modern video games. If we can’t export an .STL with it, we’re not interested. It’s just not our bag.

Oculus Rift changed this. The VR headset was originally invented for 3D video games, but quickly became a darling to hackers the world over. Virtual Reality technology is far bigger than just video games, and brings opportunity to many fields such as real estate, construction, product visualization, education, social interaction… the list goes on and on.

The Oculus team got together with the folks over at Unity in the early days to make it easy for video game makers to make content for the Rift. Unity is a game engine designed with a shallow learning curve and is available for free for non-commercial use. The Oculus Rift can be integrated into a Unity environment with the check of a setting and importing a small package, available on the Oculus site. This makes it easy for anyone interested in VR technology to get a Rift and start pumping out content.

Hackers have taken things a step further and have written scripts that allow Unity to communicate with an Arduino. VR is fun. But VR plus physical reality is just down right exciting! In this article, we’re going to walk you through setting up your Oculus Rift and Unity game engine to communicate with the outside world via an Arduino.

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A Wooden Performance Is Fine WIth This Sequencer

February 28, 2016 by Jenny List 11 Comments

You could sometimes be forgiven for thinking that making popular music has become too easy. With a laptop and suitable software almost anybody can now assemble something that had they secured the services of a canny promoter would be in with a shot at stardom. So many performances have been reduced to tightly choreographed dance acts to mask the absence of musicians or indeed musical talent, and our culture is poorer for it. It’s not that music made with modern technology or outside the performance is an indicator of lack of talent, indeed when a truly talented musician makes something with the resources of a modern technology the results are astounding. Instead it perhaps seems as though the technology is cheapened by an association with mediocrity when it should be a tool of greatness.

So it was with pleasure that we noticed a fresh project on Hackaday.io this morning which provides a marriage of accessible music technology and a requirement for performance. [Ernest Warzocha] has made a wooden sequencer.

It’s true, audio sequencers are old hat, so a new one will have to work hard to enthuse a seasoned Hackaday reader who’s seen it all. What makes [Ernest’s] sequencer different is that he’s made one with a very physical interface of wooden pucks placed in circular recesses on a wooden surface. Each recess has an infra-red reflective sensor that detects the surface texture of the puck placed in it and varies the sample it plays accordingly. It’s all held together underneath by an Arduino, and MP3 samples are played by a Sparkfun MP3 shield. At a stroke, he has turned the humble sequencer from a workaday studio tool into a performance art form that you can see in the video below, and we like that.

Home made sequencers have a special place in maker culture, and as you might expect over the years we’ve featured quite a few of them. Shift registers, CMOS analogue switches or even turntables as the sequencer elements, Lego as a human interface, a sequencer made from a cash register, and a rather lovely steampunk sequencer, to name but a few. So this one joins a rich tradition, and we look forward to more in the future.

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A Laser Cut Word Clock

July 19, 2014 by Nick Conn 18 Comments

What is a word clock? A word clock is a clock that displays the time typographically that is also an interactive piece of art. Rather than buy one for $1500, [Buckeyeguy89] decided to build one as a present for his older brother. A very nice present indeed!

There are many different things that come into play when designing a word clock. The front panel is made from a laser cut piece of birch using the service from Ponoko. Additionally, white translucent pieces of acrylic were needed to keep each word’s light from bleeding into the neighboring letters. The hardware uses two Arduinos to control the LEDs and a DS3231 RTC for keeping accurate time. The results are very impressive, but it would sure make assembly easier if a custom PCB was used in the final version. For a one-off project, this makes a great birthday present.

The craftsmanship of this word clock is great, making it well suited for any home. What projects have you built that involve more than just electronics? Sometimes, quality aesthetics make all the difference.