I do not know which one came up with the idea first, but these two web pages- AL7FS Jim Larsen and Pirate Nation Radio – show circuit board designs that fit into an Altoids box. But I also remember an IT Infrastructure Manager at a company that I used to work at that always had stacks of Altoids boxes on his desk. Wonder if any of those ‘empty’ boxes was really packing something like this little version.

The view from the front is a bit deceiving except for the little yellow tail coming out of the back. For surveillance on behalf of a legal department, this tail can easily be concealed with a bit of tape below the table; but of course the device would be in a plain black box stuffed into the LAN wire aggregator in the middle of the meeting table with the microphone dangling only slightly below the table. This is the designer ‘Altoids’ version.

The circuit design is from this Japanese group that sell circuit kits, but have apparently quit supplying this particular circuit; the diminishing production nicely coincides with changes in Japanese law that outlaw eavesdropping… hmmm… about time I thought. That was only about six years ago. The range is only about 20 meters through three different walls, so the ideal placement is a window location. The next attempt at one of these smaller versions will be a higher power version of Harry Lythall’s various designs. The particular design linked here is stable and medium range at 500 meters up to one kilometer, but by reducing the collector resistor on and changing the transistor to an old, left-over, and trusty 2N3866, I think the power can be boosted to to about 5 to 7 watts. As Smugwimp pointed out earlier, the antenna resonance needs to be measured and cut appropriately to prevent reverse current into the circuit on transmission.

The back side where the top hinges to the Altoids can is where I mounted the microphone and power switch. The power switch mounting is rough…. will do a cleaner job with the Harry Lythal circuit when I get to it later this week or next weekend.