Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

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neslou
Posts: 78
Joined: Sun Apr 12, 2015 2:53 pm

Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

Post by neslou »

Hi Everybody,
Hope everyone is ok since i didn't come to the forum since a long time ( :D the family is growing..)
I am still in my research for making my Uzebox (Nuzebox exactly) but with dip components only but even if we could left aside the AD724/725 IC with scart output like i previously did, i would like to know if according to you it will be possible to replace the AD725 encoder by the Sony CXA1645?
Thank's in advance for your help as if it is possible, the kit will be really DIY for everybody.

I have attached the datasheet.

Neslou.
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cxa1645.pdf
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CunningFellow
Posts: 1445
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

Post by CunningFellow »

Like the MC1377 (the other DIP option) the subcarrier input is 1x rather than 4x. So you will need to add a divider to the 14Mhz signal normally fed into the AD725/AD723 I think.
neslou
Posts: 78
Joined: Sun Apr 12, 2015 2:53 pm

Re: Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

Post by neslou »

Thank's for your reply CunningFellow..
I will have a look at the MC1377 you mention, but if i add another crystal at 1x instead of adding a divider, it should be ok? If i understand correctly?
CunningFellow
Posts: 1445
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

Post by CunningFellow »

Adding another xtal will mean that the two clocks (28Mhz AVR and 4Mhz colour-burst) are not in phase.

This will lead to less than pleasant looking artefacts like dot-crawl.

Just put in a ripple counter (like a 7493 or a 4040) will let you drive the clock of the NTSC encoder with the same clock.
neslou
Posts: 78
Joined: Sun Apr 12, 2015 2:53 pm

Re: Uzebox with Sony CXA1645P/M RGB Encoder (DIP Package)

Post by neslou »

Thank's again!!!
I will study this solution :)
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