Weekend Workshop: Detect radio waves (and nuclear detonations) with this DIY coherer

weekend workshop diy energy detector 032616
Need something to keep you busy this weekend? Look no further. The Weekend Workshop is our weekly column where we showcase a badass DIY project that you can complete with minimal skills and expertise. We’ve dug through all the online tutorials on the Web, and gone the extra mile to pinpoint projects that are equal parts easy, affordable, and fun. So put on your work pants, grab your tool belt, and head to the garage — it’s time to start building!

These days, impressing your friends with bleeding-edge technology means showing off your new iPhone or talking to your computer and having it search the Web for you. Unfortunately, most of your friends probably have that phone already or (more than likely) have something better. What ever happened to the diversity of show and tell? Well, thanks to an ingenious look to the past, an Instructables user may have actually found the one device capable of impressing your friends: a coherer energy detector.

Using a technique made popular during the early 1900s, Instructables user Narzan Qarma devised a way to fashion an ancient radio signal detector into something capable of sensing a very high level of energy. Comprised of little more than some metal powder, a 3V battery, and a bit of electrical wiring, a coherer energy detector might be one of the easiest (and most unique) weekend projects we’ve seen.

But what exactly would you use it for? Qarma’s own plans dub the sensor a nuclear explosion detector, capable of sensing the electromagnetic pulse given off during a nuclear detonation. While this function might seem a tad extreme, the device also has the ability to detect strong radio frequency energy, or any electrical pulse emitted nearby.

Though relatively scant on required materials, Qarma’s old-fashioned technique allows the device to work surprisingly well. Moreover, how it manages to recognize energy is incredibly straightforward. Whenever strong enough RF energy is emitted, the shaved metal filings inside the canister cling together and bridge a gap in the simple circuit, tripping the LED light.

To help you get a head start on constructing your own DIY energy sensor, we combed through Qarma’s Instructables walkthrough for all the tools, materials, and otherwise needed for the project. With as straightforward and easy-to-follow as the method is, you’ll have the ability to actually wow your friends with this old (but new) tech in no time. Here’s everything you’ll need to get started:


  • Knife
  • Screws (2)


  • Small LED light
  • Electrical wire
  • Sheet of plastic paper
  • 3V battery
  • Transformer
  • Plastic film container

With all the necessary tools and accessories at the ready, it’s time to start putting together this novel energy detector. Just follow the quick walkthrough posted to Instructables by user Narzan Qarma and before you know it, you’ll have your own unique energy sensor. Happy building!

The step-by-step walkthrough on constructing this coherer energy detector can be found here.

Emerging Tech

Awesome Tech You Can’t Buy Yet: heat-powered watches, phone cases with reflexes

Check out our roundup of the best new crowdfunding projects and product announcements that hit the web this week. You may not be able to buy this stuff yet, but it sure is fun to gawk!
Home Theater

QLED and OLED may have similar names, but they're totally different technologies

The names may look almost identical, but OLED and QLED are two entirely different beasts. In our QLED vs. OLED battle, we dissect the differences between these dueling TV technologies, and help determine which might be best for you.
Emerging Tech

The best 3D printers for 2019

On the hunt for a new 3D printer? We've got your back. Whether you're a beginner or a seasoned veteran, this list of the best 3D printers has what you're looking for.
Movies & TV

The best shows on Netflix, from 'Haunting of Hill House’ to ‘Norsemen’

Looking for a new show to binge? Lucky for you, we've curated a list of the best shows on Netflix, whether you're a fan of outlandish anime, dramatic period pieces, or shows that leave you questioning what lies beyond.
Emerging Tech

The enormous ‘Flying Bum’ moves toward a commercial design

A prototype of the world's largest aircraft is being retired as the company behind it prepares to build a production model. The new Airlander 10, also known as the "Flying Bum," could be ready for commercial use by 2025.
Emerging Tech

Face-scanning A.I. can help doctors spot unusual genetic disorders

Facial recognition can unlock your phone. Could it also be used to identify whether a person has a rare genetic disorder, based on their facial features? New research suggests it can.
Emerging Tech

Yamaha’s new app lets you tune your motorcycle with a smartphone

It used to be that if you wanted to tune your motorcycle’s engine and tweak its performance, you needed specialized tools and even more specialized knowledge. Yamaha’s new Power Tuner app changes that.
Emerging Tech

Lasers and bovine breathalyzer help determine how much methane cows produce

Cow farts and belches don't sound like catastrophic threats, but they contribute to the massive amounts of methane in the atmosphere. Recently, scientists set out to establish the numbers.
Emerging Tech

Researchers discover a way to make 3D printing 100 times faster using light

Researchers at the University of Michigan have invented a new method of 3D printing which is up to 100 times faster than conventional 3D-printing processes. Here's how it works and why it could prove a game-changer for 3D printing.
Emerging Tech

Why wait? Here are some CES 2019 gadgets you can buy right now

Companies come to CES to wow us with their cutting edge technology, but only a few products are slated to hit the market right away. Here is our list of the best CES 2019 tech you can buy right now.
Emerging Tech

Drones: New rules could soon allow flights over people and at night

With commercial operators in mind, the U.S. government is looking to loosen restrictions on drone flights with a set of proposals that would allow the machines greater freedom to fly over populated areas and also at night.
Emerging Tech

Short film celebrates New Yorker’s amazing robot costumes

New York City resident Peter Kokis creates stunning robot costumes out of household trash. His designs are huge, heavy, and extremely intricate, and never fail to turn heads when he's out and about.
Emerging Tech

In a first for humankind, China is growing plants on the moon

Having recently landed a probe on the far side of the moon, China announced that it managed to grow the first plant on the moon, too. Here's why that matters for deep space travel.
Emerging Tech

Ford’s sweaty robot bottom can simulate 10 years of seat use in mere days

Ford has developed 'Robutt,' a sweaty robot bottom that's designed to simulate the effects of having a pair of human buttocks sitting on its car seats for thousands of hours. Check it out.