>>"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 <ronc...@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 > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
