zx2020 - zx81 hybrid composite video mod
Nice mod to enable composite video on the zx81
Feed it the 5v line and the video line that normally go into the RF modulator and attach it to any earth. Inside the RF modulator detach the phono socket from the RF circuit. Then reroute the output from this mod to the phono socket.
Only try to install this if you know what you are doing. We will not be held liable for damage incurred to your zx81.
Nice mod to enable composite video on the zx81. It offers an option where the back porch isn't needed and an option where a back porch is needed.
1 on / 2 off = Requires back porch
1 off / 2 on = No back porch