In this modern day and age, ignoring the ethical issues, if you wanted to spy on someone you might check out their social media feed or even attempt to hack into the various devices that they use. On the other hand, if those methods fail to give you the results you need — and Jessica Jones is too expensive — you could plant a bug inside your subject’s car or dwelling.
While there are certainly spy microphone transmitters on the market that you can buy, that wouldn’t be much fun; and, if you’re really paranoid, others might note your recent purchase. Besides, it’s hard to imagine purchasing something much smaller than the build shown in the video below by TomTechTod.
The device measures a minuscule 5 x 9mm, and runs on a 4.8mm diameter battery that actually looks quite large next to it. In fact, when placed under a microscope just before the 1:30 mark, it’s not much larger than its field of view. Even at such a small size, this 433 Mhz transmitter is able to transmit at around 120 meters, albeit with static at that range.
While easy to conceal, the other benefit of designing a gadget this tiny is that the PCBs are extremely cheap. In fact, these little boards are shown priced at only $.45 each! The files needed to create one are available here, and once ordered, all you have to do is surface-mount solder a few dozen parts onto it, a task that will likely require a good amount of patience.
[h/t: Boing Boing]