400 Hz

Jon Elson elson at pico-systems.com
Wed May 5 11:14:04 CDT 2021

On 05/05/2021 10:07 AM, Grant Taylor via cctalk wrote:
> I have found the Motor Generator thread to be fascinating 
> and enlightening.  But it has made many a reference to the 
> 400 Hz or other frequency much higher than mains line 
> frequency.  Despite the comments about the frequency, I'm 
> still confused as to why the higher than mains frequency 
> was used.
> Were the higher frequencies used because it directly 
> effected the amount of time / duration in (fractions of) 
> seconds between peaks of rectified (but not yet smoothed) 
> power?
It made it possible for transformers, inductors and 
capacitors to be much smaller.  The 2500 Hz power supplies 
in the 360's delivered 40 A at 6 V, and used inductor-input 
filters and a final series-pass germanium transistor for 
regulation.  They were about the same size as a 6V 2 A 
regulated power supply running on 60 Hz.

So, to an extent, the answer to your question is yes.  But, 
not exactly just that, because the size of the transformer 
scaled inversely with frequency.


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