[Elecraft] regarding the green wire

[ron]

On 09/04/2011 08:07 PM, Mark Bayern wrote:
>  >>"I am aware of transformer supplies. I was referencing to switch-mode
> supplies (transformer less). I believe they have isolation between
> primary and secondary.
>
> Without a transformer? How are they getting any galvanic isolation? The
> transformer-less switched mode power supplies I'm familiar are
> most definitely _NOT_ isolated. I would like to see a design that was
> isolate.


not a bulky heavy transformer you would think of,
The inverter stage converts DC, whether directly from the input or from 
the rectifier stage  to AC by running it through a power oscillator, 
whose output transformer is very small with few windings at a very high 
frequency. (I understand the frequency is usually chosen to be above 20 
kHz, to make it inaudible) The output voltage is OPTICALLY coupled to 
the input. The switching is implemented (to achieve high gain) MOSFET 
amplifier. MOSFETs are low on-resistance and a high current-handling 
capacity.
Unless well designed, they can cause hash in AC line and be picked up by 
our ham radios.

72
Ron, wb1hga