Hi
A friend needs a phone ringing detector for his workshop, as he cannot hear it when working with his machinery. The idea is easy - when the phone rings, like old TVs - you could hear it. I detect that and knows when something is happening. Then I turn on some light.
This works well for 3G, but 4G does not show.
Basically my 3G detector is a coil under the table, which goes to the base of a transistor. A similar schematic is here:
However - 4G does not read out. I do get some 1-2 mV from the coil (up to 200mV from 3G)
Any ideas how I can react to 4G?
WBR Sonnich