On 30/07/18 14:20, Andrew Smallshaw wrote:
> On 2018-07-29, R.Wieser  wrote:
>> The Natural Philosopher,
>>
>>> Its more a case that a higher voltage needs less current for the same
>>> power.
>>
>> True. But you need to be able to convert that power to a lower voltage to
>> again become usable.  Where with AC that can be easily managed with a simple
>> transformer, that doesn't work as well for DC.
>
> You'll generally want some form of voltage regulation at the load
> end of the run in any case (to compensate for losses in the cable)
> and while in the past that may have been a linear regulator these
> days switch mode supplies are relatively simple to design thanks
> to off-the-shelf chips.  Given the reduction or elimination in
> heatsinking and/or active cooling you are likely to find such a
> solution is actually cheaper and more compact than a linear regulator
> to boot.
>
> SMPSes work theoretically losslessly by charging and discharging
> (usually) an inductor so while a linear regulator would take a
> higher voltage at full current the current decreases with voltage
> in the case of an SMPS.
>
yep. its tare to even see a transformer - just an inductor anbd
capacitor and a fast switch is all it takes

a 50% duty cycle switch feeding a eries indictor with a cap to te other
termninal on te far side will in general give a 50% voltage reduction, etc.

The higher freq. you switch it, the smaller the LC can be.

Buck converters use the flyback voltage  of an inductor (think car
ignition coil)  to generate step up voltages

transformers not used unless isolation needed.




--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

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