Ryo Mukai's One-Component Light Pen Build Replaces a Hard to Find 1980s Vectrex Accessory

Maker Ryo Mukai has designed a simple, low-cost accessory for one of the most unusual consumer electronics products of the 1980s: the Vectrex vector-based games console.

The Vectrex, designed by Smith Engineering's John Ross and launched by the General Consumer Electronics company before moving to Milton Bradley, was unique among second-generation games consoles — and remains so to this day — as being the first and only to use a vector-based display. Where rival devices like the Atari 2600 used blocky bitmaps, the Vectrex drew smooth lines on its unusual portrait CRT display.

It's the monitor which forms one-half of Mukai's build, the other half being a TT Electronics OPL801-OC photosensor. "[The] OPL801-OC is a sensor [which] consists of a photodiode, a linear amplifier, and a Schmitt trigger on a single silicon chip," Mukai explains. "The output is [a] TTL [Transistor-Transistor Logic] compatible logic level, inverted and open collector."

These features make it ideal for taking the place of the Vectrex's official light pen accessory, which allowed the user to draw directly on the screen — in a single component. Wired to the nine-pin joystick port of the Vectrex, the sensor is able to interact with the display — acting as a stand-in for the now hard-to-find original accessory.

The simple schematic for the light pen build is available on Mukai's Hackaday.io page; finding a working Vectrex, though, is an exercise left up to the reader.