Conference 7.286::atarist

    About a year ago I saw a similar project in the German magazine c't. I
    actually built that for my ST, and it works. But I do have some
    comments:
    	- The c't version does neither contain the delay line nor the
    transformer, it just contains standard parts. I built it onto a
    prototype board.
    	- The output is PAL, but can be changed to NTSC; the Motorola chip
    used is the same one.
    	- One of the two pots in my device has to be set VERY exactly, or
    the colors won't show, will be wrong (brown instead of green, etc.), or
    there is a moire. I don't know whether this is caused by using PAL or
    by the simpler design.
    	- It was easy to convert it from analog RGB to digital RGB for a
    friend owning an IBM clone with CGA.
    
    If anyone builds both versions and can compare them, or gets better
    results, please reply to this conference.
    
    Don't forget to have fun!
    		Jens

    Hello,
    
    	SO if I buy the kit for $30, I can produce composite video?
     Does anyone know how this compares to the "video key" that sells
    for roughtly $119?
    
    Tryin' to save another buck,
    
    _John_

    VideoKey is considerably cheaper than $119.  $69 I think is the going
    market rate.  VideoKey works extremely well, just one adjustment to
    make on a pot through a hole in the plastic to fine tune.  If someone
    wants to bring a TV to the next NaVAUS meeting, and an ST of some kind,
    I will let you try it (provided I can find the time to make it to the
    meeting).
    
    						-Dave

Yes, it produces composite video.

The modulator is merely a very low power TV transmitter to turn the
composite video into a RF (radio frequency) signal.

If your TV set already has a video input jack then all you need is the
project in the basenote. Or you could hook it right into your video input
jack on your VCR. (Your VCR has a modulator built right in.) Note that a
'video jack' is going to be an 'RCA' a.k.a 'phono' type plug (well, 99%
of them use RCA jacks...)

If you don't have a VCR or your TV set doesn't have a video input jack
then you need a modulator. These can (usually) be had for less than $5.
The kind of modulator that comes with an Atari 2600 game system, for
example, is exactly what you need. Mail order places often have them very
cheap.

The modulator will connect to the 'Antenna Input'. These will either
be two screws (for 300 ohm flat cable) or an 'F' connector (threaded
connector for 75 ohm coax cable).

Lee

    WOW, $69!  I remember seeing it for almost teice as much a year
    or so ago...
    
    Sounds like the "video key" is the way to go...
    
    _John_

    Hi,
    	Can someone tell me the conections I need to make to the 13
    pin Din monitor lead to connect it to a composite video monitor.
    Yes my ATARI does have composite output! The monitor has 75ohm sockets
    I think? Also the connections for Audio out.
    
    	- Andrew -
    
    P.S.	Can someone explain what the Audio in and general purpose
    pins are for???

    
    As far as I know the composite output of the 13-pin Atari connector
    is composite sync, a mixture of horizontal and vertical sync. No
    composite video. You can make a monochrome video signal with some
    resistors and a transistor out of Red, Green, Blue and composite
    sync to drive a standart monochrome monitor with video input.
    For a color video signal to feed in a VCR or TV you need the before
    mentioned device. I look up the schematic for the monochrome video
    for you, if you like.
    If you connect a audio source to the Audio-in pin of the monitor
    connector, this signal will be mixed internally with the audio the 
    Atari produces (in Yamaha's sound chip) and then they are together
    driving the monitor's speaker.
    
    Bernd
     

    Opposite to the previous reply some STs DO have composite video (I
    think, those with the FM suffix, like 520STFM [F=Floppy,M=video
    Modulator]). If this is true in your case, connect pins 2 (composite
    video) and 13 (ground) to your monitor. If you get a black picture
    only, your ST lacks composite video and has composite sync only.
    
    To answer the last question: The General Purpose Output (GPO) is just what
    its name says: for general purpose. It is a TTL compatible output
    signal, that can be switched on and off by using the XBIOS functions
    ongibit() and offgibit().
    
    Warning: Most docs have these routines wrong. The parameter is NOT a
    bit number, but a bit mask. For C programmers, to switch bit BITNO:
    
    	#define BITNO	/* whatever_you_need, from 0 to 7, look into any
    			   hardware description for the ST */
    	#define SWITCH_ON	ongibit(1<<(BITNO))
    	#define SWITCH_OFF	offgibit(~(1<<(BITNO)))
    
    Have fun, Jens

	Hello.
	I just get the last number of a electronic magazine,
	named 'Allt om elektronik', and this is a Swedish
	version of the English magazine 'Elector Electronic'.
	They have a description of a converter from RGB to
	PAL composite video. And it made for computers like 
	ATARI. They have description how to wire it up to
	ATARI-ST.

		Anders

    Hej pa dej anders,
    kan du skickar mej ett kopia av detta.
    tack skar du har.
    rolf'en
    vaxmail suosw4::surauf