5-Minute Project: How to build a "Circuit Sniffer" March 13, 2013 18:24 12 Comments

Here's a fun little noise-maker you can build for under $5 in under 5 minutes: a "Circuit Sniffer." Just as microphones pick up vibrations in the air and turn them into an alternating electrical current, this little device picks up the magnetic fields emitted by electronic devices. You can get some pretty brutal sounds by just plugging it into an amp and probing your household appliances. Check out the video below (4:09) to see what it does and how to build it.

Sourcing component(s)

There is only one component involved here, an inductor. Inductors are measured in Henries; the higher their value, the greater a voltage they can induce from the same change in current. What this means for us is that higher value inductors will have a louder output and need less amplification. I used a 1000uH inductor in the video which is about the minimum value I would suggest to maintain a useful output level. Healthy-sized inductors often pop up in electronics surplus stores like All Electronics or Electronics Goldmine for less than a dollar each. Here are a couple that are available at the time of writing: Besides our inductor, all you need is a cable to get the signal to an amp. The standard choice here is an unbalanced 1/4" which can be found at any Radioshack or music store in the world. Happy probing! If you stumble upon any especially crazy sounding devices, please share you findings here. Many thanks to Nicolas Collins, author of "Handmade Electronic Music" for turning me on to this idea.