16 Jan
1998
16 Jan
'98
3:17 p.m.
On 15 Jan 98 at 22:59, Tony Duell wrote:
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
lwalkerN0spaM(a)interlog.com
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