Analog Devices rock

ttooddddyy · Nov 19, 2003

Finally got around to wiring up the sample AD725 PAL/NTSC encoder tonight, It works really well (better than expected for some reason) btw this is my first supergun project. Its running PAL and I must say the results are good. Connected to comp video there is very little cross chrominance or anything else anoying thats really noticable, yet to wire the s-video. Im sure there have been several threads on this, but thought that AD was worth a mention again. Anyone with any tips on the usage.

norton9478 · Nov 19, 2003

Great...

where did you get your chip from???

I'd like to learn how to wire these but I don't quite have the skills yet/.

ttooddddyy · Nov 19, 2003

Go to ADs website, there you can order two free samples for evaluation/development purposes, they ship straight away, get the data sheet there. http://search1.analog.com/searchProxy.asp?queryText=

Arakon · Nov 19, 2003

argh.. how did you wire it up? if possible take a few pics of the pcb..

I still have interferences in mine, like thin shadow lines in the background, and no matter how I wired it up and set up the combination of components, they always are there.

ttooddddyy · Nov 19, 2003

The AD 725 was piggy back superglued to the top of the74HC04 hex inverter. I used a project board, not vero with the continuous tracks, it makes it easier for this type of project Ive found.
Then jumped off the AD725 pins to the project board.
OK its not a pretty sight but it works, very slight cross chroma but hardly noticable, im going to fine tune the luma trap to reduce this, it will not be noticable on s-vid anyway. Otherwise no hint of interference of any kind.

norton9478 · Nov 19, 2003

Yay... I ordered two free samples to my fake company....

I get two chances to make one without messing up...

I might make a TV adaptor for my VGA card if i get it on the first try...

Now all in need to do is learn how to read electronics schematics....

I can ignore the whole Y (luma) trap part right? I don't plan on using composite.

Where did you get the other parts such as the clock and stuff?

Reznor007 · Nov 19, 2003

You can make a VGA adapter, but you must force your video card to run at 15KHz. It normally works at 31KHz or higher, which will not work on a TV.

ttooddddyy · Nov 19, 2003

norton9478 said:
Yay... I ordered two free samples to my fake company....

I get two chances to make one without messing up...

I might make a TV adaptor for my VGA card if i get it on the first try...

Now all in need to do is learn how to read electronics schematics....

I can ignore the whole Y (luma) trap part right? I don't plan on using composite.

Where did you get the other parts such as the clock and stuff?

You will not require the luma trap components if you intend to use s-video only.
I got the other components from Radio Spares Australia. The trickiest thing to locate is the xtal which is 4X chroma reference oscillator frequency. 14.32 Meg for NTSC.

ttooddddyy · Nov 20, 2003

Arakon said:
argh.. how did you wire it up? if possible take a few pics of the pcb..

I still have interferences in mine, like thin shadow lines in the background, and no matter how I wired it up and set up the combination of components, they always are there.

Arakon
Are you runing the encoder in ntsc or pal, dont really think its an issue, but pin (forget the #) enables one or the other and it has an affect on the luminance trap. What does your set up look like using s-video ???

Electroman · Nov 20, 2003

You guys ought to consider using surfboards for prototyping your SMD devices.

Digikey has a whole array to choose from:

Digikey part number A726-ND is a 16SOIC to DIP adaptor.

Capital Advanced Technologies has a whole array of 16 SOIC to miniboard adaptors you can use too. Just search in Digikey for "Surfboard", then select 16-pin.

Arakon · Nov 20, 2003

I've used NTSC. where does that hex inverter come into play, I don't recall one in the datasheet?

http://pirate.sparkhost.com/~arakon/encoder.jpg

Robert · Nov 20, 2003

What is the SP bottle close to the TV? Beer?

ttooddddyy · Nov 20, 2003

Robert said:
What is the SP bottle close to the TV? Beer?

South Pacific Lager. The beer of paradise

ttooddddyy · Nov 20, 2003

Arakon said:
I've used NTSC. where does that hex inverter come into play, I don't recall one in the datasheet?

http://pirate.sparkhost.com/~arakon/encoder.jpg

Its part of the 4FSC clock generator. 14.3 MHz in NTSC and 17.7 MHz in PAL. What clock circuit are you using ?

norton9478 · Nov 20, 2003

I think my radioshack sells the adaptor for this chip...

wiseman9986 · Nov 20, 2003

what does the clock do??

ttooddddyy · Nov 20, 2003

wiseman9986 said:
what does the clock do??

Its for the chrominance (color signal) sub carrier sampling reference.
In this circuit it is actually 4 X the normal reference oscillaor freq.
Its called 4FSC. 3.58=14.3 MHz in NTSC and 4.43=17.7 MHz in PAL

Arakon · Nov 20, 2003

I'm using a straight 14.318 mhz oscillator for the clock.. the color is perfectly fine, except for the interferences.

ttooddddyy · Nov 20, 2003

Are you using the 5 volts thats supplied to the edge connector. If so I wonder if there is any noise.Try running off the 12 volts through a 7805. Just a long shot.

wiseman9986 · Nov 20, 2003

any body else that has built this can u campare with jrok??

Arakon · Nov 20, 2003

I have done that, and used an external PSU too, with no change at all to the interferences. I built circuits with both the 724 and 725, with way different component placements and stuff, without any change whatsoever... changed from normal to high quality components, with "great RF qualities" etc, with no difference.

ttooddddyy · Nov 20, 2003

Arakon
Could you put up a piccy of the interference. We must get to the bottom of this

Reznor007 · Nov 21, 2003

wiseman9986 said:
any body else that has built this can u campare with jrok??

I built one using an AD725. My Street Fighter 2 CE PCB looked really good, but a few other games just looked bad...like, messed up colors and such. I never really looked into that part much though as I ordered a JROK.

I would rate the JROK a bit above my encoder, with the simplicity level way above it

MKL · Nov 21, 2003

Reznor007 said:
I would rate the JROK a bit above my encoder

Anyone know what encoder chip is used on the jrok? certainly not the AD725 cause the pin number is different...I can't seem to read anything on it in closeup pics, probably they sanded it...

ttooddddyy · Nov 21, 2003

I read somewhere its a Sony ?

Analog Devices rock

PNG FTW,

So Many PostsNo TimeFor Games.

PNG FTW,

Robert Garcia's Butler

PNG FTW,

So Many PostsNo TimeFor Games.

Host for Orochi

PNG FTW,

PNG FTW,

, ,

Robert Garcia's Butler

,

PNG FTW,

PNG FTW,

So Many PostsNo TimeFor Games.

Krauser's Shoe Shiner

PNG FTW,

Robert Garcia's Butler

PNG FTW,

Krauser's Shoe Shiner

Robert Garcia's Butler

PNG FTW,

Host for Orochi

Basara's Blade Keeper

PNG FTW,

So Many Posts
No Time
For Games.

So Many Posts
No Time
For Games.

So Many Posts
No Time
For Games.