Series circuit - 3 LEDs

It's not quite a backdoor, but don't underestimate what can be hidden in seemingly simple places: link to this video Here's how that is doing it: link He's got several more, including this one which doesn't even use switches. You just tap the wire to toggle the LEDs: link I have no idea how that one works.

Obviously not at SMD scale, but I have seen fun videos with seemingly simple circuits with LEDs and switches connected in series and they behaved completely differently (eg. each switch connected in series controlled other LED). It turned out that switches and LEDs have been modified with clever frequency generators and filter circuits. edit: link to this video

…nents. It's already been demonstrated journalists will gladly plug random USB devices into their computer. If you wanted the device to just pass a cursory investigation, you'd just put a glob of black epoxy over the USB port. Hiding a microcontroller as a pair of resistors might be possible, but it's far more effort than what is really needed. 1 link to this video 2 link…