This is a small passive adapter that converts CGA, MDA or EGA TTL signals into analog signals for use with video scaling devices such as the Extron IN1606. Note: this device does not create a VGA compatible signal, it just converts the digital signals to analog. A suitable capture or scaling device, or multi-scan monitor will still be needed.

The circuit is based around simple resistive dividers to provide two brightness levels for the video signals according to the intensity signal provided by the computer. Because of pin incompatibilities between CGA/MDA and EGA there is a set of solder jumpers on the underside to select between either CGA/MDA mode or EGA mode.

Using it

Simply plug this into your vintage computer's video output, and plug a VGA cable from this into your compatible video scaler.