ZX80 Composite Mod

[Brinmania]

Hi

I've just bought my first ZX80, and at some point in the past it has had a rough and ready composite mod done to it (the same type as you can do the the spectrum). my question is can you improve this with a capacitor, like on the spectrum, or is it better to do the transistor composite mod

Thanks

Andy

[1024MAK]

Hello Andy

Because the video is mixed with the sync signal via resistors (for both the video and the sync), an active amplification stage is recommended, hence I suggest the transistor version. You can see my transistors version for the ZX81 via the link in my signature (below).

Mark

[Paul]

For a ZX80, that never had a backporch, I recommend adding a backporch generating device. I use Pokemon's version.
Kind regards Paul

[1024MAK]

For a ZX80, that never had a backporch, I recommend adding a backporch generating device. I use Pokemon's version.
Kind regards Paul

Yes, his ZX8-CCB is what I would normally recommend, but his shop is currently closed due the the COVID19 Corona virus outbreak. His Sell My Retro shop is here.

Mark

[Brinmania]

Thanks for the advice guys, I'll have a look at both your circuit Mark and Pokemon's as well

Thanks

Andy

[bola_dor]

I have my ZX80 connected with non backporch mod but the TV takes it well. I was lucky I guess. Some times I have to force it making it SAVE and when back the video is OK.
But if you are not lucky with the TV with the simple transistor mod you can go with the 555 based mod that builds the missing backporch
http://zx.zigg.net/misc-projects/