In article , David Looser
 scribeth thus
>"Don Pearce"  wrote in message 
>news:4a5c1ddc.1504123750@localhost...
>>
>> Pretty much yes. In the case of my description it is just a question
>> of where you inject signal into a transformer, and the resulting
>> phases across the various windings.
>>
>
>Exactly, the apparent complication in a real CB telephone is simply the need 
>to have the carbon microphone in the line circuit in order to get the DC 
>line current flowing through it. But the principle is exactly the same.
>
>Of course these days it's all done in a chip which does everything: puts a 
>low value resistance across the line (whilst powering itself from it) 
>provides a pre-amp for the electret or moving coil microphone and a 
>low-impedance output to drive the moving coil earpiece, and performs the 
>hybrid function using an op-amp. No fun anymore.
>

And receives mobile phone signals so you know its going to ring before
it does;!...


-- 
Tony Sayer