A simple circuit based on the LM1881 to split the Composite Sync signal into H- and V-Sync could be this:
{||-| [[File:CPC2VGAschematics.png|thumbnail|none|CPC2VGA LM1881 schematics]]|| [[File:Cpc2vga_plain.jpg|thumbnail|none|CPC2VGA - PCB fully built]]|| -|}