Did some work on ZX Spectrum 128 +3 I have. One thing was I wanted to make it work with small “TFT Color monitor” (for a car rear view). This monitor has a composite video input.
First I tried using CSYNK and GND signals for a composite video input. You get the video but it was terrible quality. It seems that “The 128 ZX Spectrums including the +3 (and +2A, +2B) have audio sound modulated onto the video, which reduces the clarity of the composite signal that is available at the modulator input.”(1).
Then I found this document – “Video fixes and video cables
for all ZX Spectrum 128K models”. There is a chapter on Creating composite video-out on a +2A / +2B / +3:
“Although the ZX Spectrum 128K heat sink model and the grey ZX Spectrum +2 have a composite video-out signal on pin 1 of the RGB connector, the ZX Spectrum +2A, +2B and +3 are missing this feature.
Instead of the composite video signal they have a dangerous 12V on pin 1 that will seriously damage your TV or monitor!
But you can add the composite video signal yourself, with the same fairly simple circuit as that is integrated on the heat sink model and +2.
1. First remove the 12V from pin 1 by removing resistor R44 (should be the same for +2A, +2B and +3, and very close to the RGB connector).
2. Add this circuit:”
Recently have finished this book. From the times of Plato and Aristotle our brain and way of thinking is changing and adapting to our way of living. Every tool we use becomes a part of us, but also we become a part of a tool we use. Clock, written word, computers, world wide web. Everything we use changes us, changes how we think, changes how we remember things.
Its a good read that raises a lot of interesting topics.