should I do the composite mod?

[Seeker]

I'm thinking about doing a composite mod on my 81. Is it worth it, is the picture visually enhanced a lot?

[Moggy]

The short answer is yes most certainly.

Unless you posses an old style CRT B/W television then the odds are you have a modern LCD type. These do not play nicely with with the 81 sadly but luckily there are ways to combat this.

One such method provided by 1024MAK is in a thread here near to the thread bottom..
viewtopic.php?f=7&t=872&p=8749#p8749

Another way is to do the single transistor mod which is the most primitive method as it does not provide a back porch signal which is needed for modern TV's and unless you have the later ULA found in most issue three 81's which does provide that signal then this method may not be so useful
viewtopic.php?f=7&t=3677&p=41051&hilit= ... mod#p41051

One of the best ways in my opinion is ZX8-CCB video board made and sold by Pokemon on the sell my retro site unfortunately I believe he has stopped making them during the current pandemic but the site is worth noting if he should start up again this board also provides inverse video with full black border either by way of added switch or jumper.
https://www.sellmyretro.com/offer/details/3712

There me be other ways that others are aware of and no doubt will be glad to help you with.


EDIT
Whilst I remember, I only seem to get the "jailbars " effect when using the transistor mod.

[1024MAK]

Does it improve the quality of the picture compared to RF/UHF? Yes.
Will the simple composite modification using a NPN transistor and resistor produce the best picture? No, but it’s better than the picture via the RF/UHF connection.

I recommend one of Pokemon’s ZX8-CCB boards. There are other alternatives available. These clean up the video signal and give a nice sharp clean display.

Mark

[Seeker]

I'm using it with an older 14 inch CRT TV, But it sounds like If I want to use anything else I need to do the mod, so I will.
Thanks for the links!

[Spinnetti]

There's also this one which seems a bit fancier and is more expensive, but I don't know the technical differences. I ordered one but not got it working yet.

https://www.sellmyretro.com/offer/detai ... it%29-2338

[Lardo Boffin]

There is a discussion here about the various composite mods:

viewtopic.php?p=21765#p21765

I have a TS1500 and a ZX81 with the ZX-Vid fitted.

[1024MAK]

There is also the composite video board based on the NE555 chip...

And a general composite video board (from the future is eight bit) that is just an emitter follower transistor circuit...

So plenty of choice

Mark

[mrtinb]

If you havn't seen it, there is also now the ZX-Wespi-V model, that outputs flawlessly to VGA. Cheap ZX81-to-VGA board with built-in tape-emulator.

[Lardo Boffin]

If you havn't seen it, there is also now the ZX-Wespi-V model, that outputs flawlessly to VGA. Cheap ZX81-to-VGA board with built-in tape-emulator.

Looks interesting. I keep meaning to have a go at doing one of those.

[Seeker]

If you havn't seen it, there is also now the ZX-Wespi-V model, that outputs flawlessly to VGA. Cheap ZX81-to-VGA board with built-in tape-emulator.

WOW! VGA for the 81!?? That's amazing!