It’s a staple of spy thriller movies, that the protagonist has some kind of electronic scanner with which he theatrically searches his hotel room to reveal the bad guys’ attempt to bug him. The bug of course always had a flashing LED to make it really obvious to viewers, and the scanner was made by the props department to look all cool and futuristic.
It’s not so far-fetched though, while bugs and hidden cameras in for example an Airbnb may not have flashing LEDs, they still emit RF and can be detected with a signal strength meter. That’s the premise behind [RamboRogers]’ RF hunter, the spy movie electronic scanner made real.
At the rear of the device is an ESP32, but the front end is an AD8317 RF detector chip. This is an interesting and useful component, in that it contains a logarithmic amplifier such that it produces a voltage proportional to the RF input in decibels. You’ll find it at the heart of an RF power meter, but it’s also perfect for a precision field strength meter like this one. That movie spy would have a much higher chance of finding the bug with one of these.
For the real spies of course, the instruments are much more sophisticated.
That is a great looking design. Clever use of the log detector. I’ve seen a few bits of homebrew test gear that use it too. Thanks for sharing l
The NLJD in the previous articles linked website is a gem! https://web.archive.org/web/20190420141213/http://67.225.133.110/~gbpprorg/perl/555.txt The long list of RF related Perl scripts is a blast from the past.
Look at this 555 calculator complete with ASCII diagrams!
I had to follow your link to see if the 555 was being used as a calculator, or if it the calculator was used for 555 component values. (The latter)
Interesting stuff – have a look at the rest (below) on that now-suspended site (GB likely meant Green Bay, WI)
https://web.archive.org/web/20190420140949/http://67.225.133.110/~gbpprorg/
What appears to be the current “GBPPR Advanced Development Projects” site: http://www.gbppr.net/proj.html