Low blue light filter for VGA


I have created a hardware low blue light filter for VGA interface. It is useful e. g. for a vintage DOS machine that does not have software support for this. The principle is very simple - resistors are added to blue and green analog lines. The designed pcb allows for usage of trimpots to adjust the desired color shade. All other signals, including sync signals and red analog line, are connected directly. Concerning the resistor values, I came up with values of 100 Ohm for blue line and 39 Ohm for green line - this creates a nice orange-sepia tint. Adding resistor just to blue line would create image that looks very yellow, which does not look good. The circuit also contains a switch that bypasses the resistors, which in effect disables the filter and shows original colors.

Parts used:

  • Male VGA connector
  • Female VGA connector
  • 2-pole switch
  • 2 trimpots (or resistors) with appropriate values (1k trimpots should work well)


  • VGA F/F Gender changer
  • Enclosure

Schematic and PCB can be found here.

Soldering did not take too long, as can be seen in the video: