Amstrads in the US

From: Lawrence Walker <>
Date: Fri Jan 16 23:17:55 1998

On 15 Jan 98 at 22:59, Tony Duell wrote:

> >
> > OK I'll get an EE to help me out. Did you ever used that with a monitor? is
> > the 60 Hz vs 50 Hz a problem?
> AFAIK, no computer (at least no micro or mini) ever used the mains
> _frequency_ for anything more than a real time clock interrupt and
> running the fans.
> Ditto monitors. Every monitor I've ever looked inside (or read the
> service manual for) has used the mains to produce DC rails only. I've got
> a lot of 60Hz video monitors here (UK, 50Hz mains) with no problems.
> TV vertical rates are close to the mains frequency. This was for a couple
> of reasons - to prevent the image 'beating' with room lights and to
> prevent any residual mains hum causing very annoying flicker if the TV's
> smoothing wasn't perfect.
> Some disk drives (large hard disks, 8" floppies, etc) did have
> synchronous motors. There's typically a different pulley and belt needed
> when you change frequency.
> -tony
 One of the problems was the frequency. I have some old Atari
programs that allowed you to change between 50mhz <>60 mhz
to get rid of the screen flicker.

ciao larry
Received on Fri Jan 16 1998 - 23:17:55 GMT

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