convert VHS to DVD

Tim ignored_mailbox at yahoo.com.au
Wed Mar 14 04:19:22 UTC 2007


On Tue, 2007-03-13 at 11:29 -0600, Mike McCarty wrote:
> Yeah, I didn't like the output stage, either. It consumes a *lot* of
> power. It would be much better with active pull-up, or even just an
> emitter follower output stage. He's creating a 75 ohm output
> impedance, and wasting a lot of power doing so.

I'm not so sure that he's even managing that (75 Ohms).  I have my
doubts you'd get the normal responses to a proper 75Ω output if you
played around with the end termination.  I've found circuits like that
to do strange things with frequency response if you have less than ideal
termination in the rest of the signal path.

> Also, I'd rather have a couple of crystal controlled counters than
> one-shots controlled by pots. Its one big advantage is being cheap
> and easy to build. 

I used to build vision mixers that did wipes that way.  I gutted an old
TV game with X-Y pot controllers to build a square wipe controller.  One
game controller controlled the top-left corner position, the other did
the bottom-right corner.  It made it quite easy to position a mask
around things.  ;-)

-- 
(This box runs FC6, my others run FC4 & FC5, in case that's
 important to the thread.)

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