[QuadList] Servo Modes

[Norman Hurst]

The Dischert invention was demoed to lock in less than 6 frames from the time you pushed play.  That's 200 ms.  It was amazing.


The figure on the first page of the patent shows the acceleration profile relative to house reference.  

  http://www.google.com/patents?id=K043AAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false



________________________________
 From: C. Park Seward <park at videopark.com>
To: Norman Hurst <gnormhurst at yahoo.com>; Quad List <quadlist at quadvideotapegroup.com> 
Sent: Thursday, August 23, 2012 12:26 PM
Subject: Re: [QuadList] Servo Modes
 

I can get my 1200s to lock up almost instantly. It usually requires tweaking the servos for that particular tape. But most any tape will lock in two seconds or less.


Best,
Park

C. Park Seward
Cell: 818-535-2747
Home: 541-476-6657
2" Quad and 1" "C" transfers
The Transfer Lab at Video Park
Visit us: http://www.videopark.com



On Aug 23, 2012, at 5:21 AM, Norman Hurst wrote:


>
>In the 1970s, my father led an Advanced Development group at RCA Broadcast and one of their projects was to improve the lockup time for VTRs.  Using a TR-70C, they developed a way to achieve lockup within a time measured in frames, not seconds:
>
>  
>
>  http://us.mg4.mail.yahoo.com/neo/launch?.rand=229377417&clmigstart=20110815
>
>
>
>It worked by applying an acceleration profile such that when the tape reached the correct speed, it was also in phase with house sync.  I remember that to demonstrate it they had to manually hold the pinch roller against the capstan and keep the electronics in E-E until playback was locked.
>
>
>
>The group was in the Terminal Equipment group, not in the VTR group.  When they demoed the system to the VTR group, it got the "NIH" reception: Not Invented Here.  It never made it into any product.
>
>
>
>
>________________________________
> From: Don Norwood <dwnorwood at embarqmail.com>
>To: Quad List <quadlist at quadvideotapegroup.com> 
>Sent: Tuesday, August 21, 2012 2:38 PM
>Subject: Re: [QuadList] Servo Modes
> 
>
>
>
> 
>Hi Chris:
> 
>I have a VR-1200 that has a mod so that in H-lock mode, it 
functions exactly as you have described for the RCA LineLock.  It's a small 
circuit board added in the control panel.  Basically an NE555 
timer controlling mode selection when Play is activated and the 
servo selector is set for H-lock mode. 
> 
>Don Norwood
>Digitrak Communications, Inc.
>www.digitrakcom.com  
> 
>----- Original Message ----- 
>From: Chill315 at aol.com 
>> RCA offered four modes of lock, Pixlock, LineLock, Switchlock, and  TW or Tone Wheel.
>> 
>>Pixlock was the same as Automatic in the Ampex Machines.  Linelock  starts in full automatic and then after lock reverts to the same as  Horizontal, Switchlock was vertical lock, and TW is the original servo  system.
>> 
>>RCA did have the advantage with LineLock that it would always lock  vertically for a clean switch and then if there was a problem, have a fast  servo recovery.
>> 
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