Both Energous’ WattUp and Ossia’s Cota mobile device charging systems work much like a wireless router, sending radio frequency (RF) signals that can be received by enabled wearables and ...

HF radios often use toroidal transformers and winding them is a rite of passage for many RF hackers. [David Casler, KE0OG] received a question about how they work and answered it in a recent video ...