[Elecraft] regarding the green wire

[Mark Bayern]

>>"whose output transformer is very small with few windings ...

But that is not a transformer-less SMPS. It does have a transformer.

I'm done with this discussion.

Mark



On Mon, Sep 5, 2011 at 10:05 AM, ron <roncasa at verizon.net> wrote:

> 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
>