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Re: CPLD replacement for ZX8301

Posted: Mon Jan 30, 2023 1:28 pm
by lliont
Tested it with (but with R4=330)
scart_con.png
scart_con.png (7.37 KiB) Viewed 2000 times
and got

scart_col.jpg
scart_sub.jpg
(This small LCD TV I use just for testing is bad and darker on top than bottom so camera can't adjust brightness correctly, result is better live)

The only thing that remains to be determined is what to use for blanking signal, using just the csync works but it has some rare random very short periods of blank screen at the TV I tested it. Could be this stupid tv.
Use what QL scart cables use.

Maybe better change R88 to 47 Ohm in the above

One can also use a resistor mixer like the one on the pcb, more components but they 'll fit in the scart cable connector.

So if one doesn't need the BW video of pin 3 this is a solution, thanks tofro

Re: CPLD replacement for ZX8301

Posted: Mon Jan 30, 2023 6:16 pm
by Cristian
If I may leave a suggestion, I think one of the crucial colors to obtain is the orange (if possible!)

Re: CPLD replacement for ZX8301

Posted: Mon Jan 30, 2023 9:30 pm
by lliont
Here replaced one of the 2 blacks with light orange (4th bar) but this needs the pcb resistor mixer (2 bits per color) to be produced so the photo is from crt monitor and the composite video output. From my previous post's circuit this will look yellow.

Here with lowered monitor's brightness to look better in photo from crt
orange.jpg

Re: CPLD replacement for ZX8301

Posted: Tue Jan 31, 2023 7:28 pm
by Cristian
Great result!

Re: CPLD replacement for ZX8301

Posted: Tue Jan 31, 2023 11:56 pm
by ones' complement
Cristian wrote: Tue Jan 31, 2023 7:28 pmGreat result!
But why is orange so appeeling? (no really, I'm not just taking the pith)

Re: CPLD replacement for ZX8301

Posted: Wed Feb 01, 2023 7:26 am
by NormanDunbar
Outspanding pun!

Re: CPLD replacement for ZX8301

Posted: Thu Feb 02, 2023 11:41 pm
by ones' complement
Jape aside (no disrespect, Cristian), of course orange (& green, purple), are secondary colours in paint pigments, in light spectrum; magenta, yellow, cyan. :D

Re: CPLD replacement for ZX8301

Posted: Fri Feb 03, 2023 12:25 pm
by lliont
I don't know about the light spectrum but ZX Spectrum doesn't have orange :lol:

Re: CPLD replacement for ZX8301

Posted: Fri Feb 03, 2023 1:29 pm
by XorA
Scotland would be a much better place without Orange :-D

Re: CPLD replacement for ZX8301

Posted: Fri Feb 03, 2023 3:37 pm
by NormanDunbar
XorA wrote: Fri Feb 03, 2023 1:29 pm Scotland would be a much better place without Orange :-D
I see what you did there! ;)