[rec.video] Video signal generator

khayo@sonia.cs.ucla.edu (Erazm J. Behr) (01/14/88)

Is there a *simple* circuit that would produce a video signal
which could be recorded on a VCR as a "blank space" between
programs, movies etc.? When no signal is present the VCR has
no synch information (or so it seems to me, I know *0* about
this) which gives unpleasant results. I'm sure a $500 diagnostic
signal generator would do that, but I'd like to make a bare-bones
little gizmo that would hook up to the video input and do this.
Is it feasible?  Thanks in advance!                    Eric

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          >>>>--------------->         khayo@MATH.ucla.edu 

brown@nicmad.UUCP (01/16/88)

In article <10423@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr)) writes:
<Is there a *simple* circuit that would produce a video signal
<which could be recorded on a VCR as a "blank space" between
<programs, movies etc.?

I use a camera with the lens cap left on.
-- 
	       harvard-\	       ihnp4--\
Mr. Video               !uwvax.................!nicmad!brown
	       rutgers-/  terminus-/  decvax--/
"... a can of deodorant that measures nine on the Richter scale?"

khayo@sonia.cs.ucla.edu (Erazm J. Behr) (01/17/88)

In article <2341@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
 >In article <10423@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr)) writes:
 ><Is there a *simple* circuit that would produce a video signal
 ><which could be recorded on a VCR as a "blank space"...
 >I use a camera with the lens cap left on.
Hah! good idea, but I *don't have a camera* ! Thanks anyway.
By the way, I wouldn't throw flames as Mr. Milne does, but as a dedicated
enemy of kludges of all shapes and forms I can sort of see what he means,
Mike. But thanks for all the other :) useful info you post.     Eric
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          >>>>--------------->         khayo@MATH.ucla.edu 

brown@nicmad.UUCP (Mr. Video) (01/18/88)

In article <10494@shemp.UCLA.EDU> khayo@MATH.ucla.edu (E. Behr)) writes:
<In article <2341@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
< >In article <10423@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr)) writes:
< ><Is there a *simple* circuit that would produce a video signal
< ><which could be recorded on a VCR as a "blank space"...
< >I use a camera with the lens cap left on.
<Hah! good idea, but I *don't have a camera* ! Thanks anyway.

I was afraid that would be the case.  But sometimes a simple answer like
using a camera is easily forgotten/overlooked.

If you can find a sync generator chip, it wouldn't be hard to build one.
The sync generator chip that I have is no longer made, so I haven't looked
to see what is out there nowdays.  Maybe someone else on the net can
recommend the latest chip that is out there.  From there spec sheets can
be found to help build a circuit.

<By the way, I wouldn't throw flames as Mr. Milne does, but as a dedicated
<enemy of kludges of all shapes and forms I can sort of see what he means,
<Mike. But thanks for all the other :) useful info you post.     Eric

Thanks for the confidence.

You know, maybe I should put together a black level generator/switcher
and sell it.  The circuit would allow you to input video and audio from
a source and output black level until the stuff you wanted to record
started.  I have that problem all the time.  An interesting thought.
-- 
	       harvard-\	       ihnp4--\
Mr. Video               !uwvax.................!nicmad!brown
	       rutgers-/  terminus-/  decvax--/
"... a can of deodorant that measures nine on the Richter scale?"

tim@mtxinu.UUCP (Tim Wood) (01/19/88)

In article <2341@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
>In article <10423@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr)) writes:
><Is there a *simple* circuit that would produce a video signal
><which could be recorded on a VCR as a "blank space" between
><programs, movies etc.?
>
>I use a camera with the lens cap left on.

Or, just switch the VCR input to LINE (CAMERA).  My Sony SLHF750 shows
a uniform light gray screen for the floating video input, and no audio signal.
No as nice as black screen but I don't have $x000 for a camera & lenscap :-)!
-TW
-- 
{ihnp4!ptsfa,pyramid,{uunet,ucbvax}!mtxinu}!sybase!tim

brown@nicmad.UUCP (Mr. Video) (01/20/88)

In article <554@mtxinu.UUCP> tim@mtxinu.UUCP (Tim Wood - Sybase Inc.) writes:
<In article <2341@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
<>In article <10423@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr)) writes:
<><Is there a *simple* circuit that would produce a video signal
<><which could be recorded on a VCR as a "blank space" between
<><programs, movies etc.?
<>
<>I use a camera with the lens cap left on.
<
<Or, just switch the VCR input to LINE (CAMERA).  My Sony SLHF750 shows
<a uniform light gray screen for the floating video input, and no audio signal.
<No as nice as black screen but I don't have $x000 for a camera & lenscap :-)!

What is wrong with this idea is that:

	1. Not all VCRs play back this blank area as gray.
	2. There isn't any sync for the VCR and TV to lock on to.
	   This creates a jump problem when playing back the tape.
-- 
	       harvard-\	       ihnp4--\
Mr. Video               !uwvax.................!nicmad!brown
	       rutgers-/  terminus-/  decvax--/
"... a can of deodorant that measures nine on the Richter scale?"

khayo@sonia.cs.ucla.edu (Erazm J. Behr) (01/21/88)

Thanks to all who responded to my original question.
Sorry, can't acknowledge by mail.
Looks like one has to have a generator of some sorts. Switching
to Line input causes problems with synch, as Mike noted. Norm
Strong suggested this plus *shorting* the input - may help, but
haven't tried it yet. It seems strange that no VCR I know of
has this feature (a la "rec. mute" in most audio decks). Eric
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          >>>>--------------->         khayo@MATH.ucla.edu 

ags@j.cc.purdue.edu (Dave Seaman) (01/21/88)

In article <10594@shemp.UCLA.EDU> khayo@MATH.ucla.edu (E. Behr)) writes:
>It seems strange that no VCR I know of
>has this feature (a la "rec. mute" in most audio decks). Eric

The Sony SL-HF1000 has a built-in "black screen generator" as well as a
built-in character generator.

-- 
Dave Seaman	  					
ags@j.cc.purdue.edu