Hi,
Another card from Wilf Rigter work, for ZX81,TS1500 or SPECTRUM.
The LCD display card.
https://quix.us/timex/rigter/ZXLCD.html
(On the SPECTRUM, you probably had to strap the diode D1)
ZX81 Wring diagram:
Kicad Project: (Gerber-PCB-ZX81 ASM)
http://abandon.pcbs.free.fr/wilfrigter/LCD_Display/
Have fun.
Wilf Rigter's LCD card [Kicad]
Wilf Rigter's LCD card [Kicad]
Xavier ...on the Facebook groupe : "Zx81 France"(fr)