A Video Vectorscope Oscilloclock

Tek 520A Oscilloclock

Back in the days of analog TV, vectorscopes were used to view video signals. [Aaron] has taken an old Tek 520A NTSC vectorscope and converted it into his newest oscilloclock.

The scope was originally designed to look at the signal provided by composite video. It draws vectors on a polar plot. By using test patterns such as color bars, you can ensure equipment is creating the correct color output. These scopes were so commonly used that many digital systems still provide a simulated vectorscope for color analysis. Vectorscopes were designed to be left on constantly, which is a good quality for a clock.

[Aaron] has a history of converting oscilloscopes into clocks, which we have featured in the past. This build is similar, using his custom control hardware to drive the display. Since analog vectorscopes are pretty much obsolete, you can find them on eBay at low prices, so these oscilloclocks could be relatively cheap to build.

In the write up, you get a teardown of the Tek 520A, showing the modifications made to build the clock. After the break, check out a video of the Tek 520A Oscilloclock.

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Turning Grandpa’s o-scope into a clock


Around 1960, [Aaron]’s grandfather decided to try his hand at a new career in electronics repair. It didn’t pan out, but before he gave up he built a beautiful Heathkit oscilloscope, a model OR-1. Grandpa’s electronics career never took off, but years later it would serve as the impetus for [Aaron]’s own career in electronics. Now [Aaron] has too many oscilloscopes, but still wanted a way to preserve his grandfather’s legacy. An oscilloclock was just the project to do that.

Of course to turn an oscilloscope into a clock requires some interesting control circuitry, and [Aaron] didn’t skimp on his build. He created a custom control board that is able to draw any shape on the CRT screen using just circles; squashing circles to draw a line, and cutting the beam entirely to slice a circle in half.

This isn’t [Aaron]’s first oscilloclock by a long shot. He previously created this amazing clock completely from scratch. Still, using Grandpa’s old tools is a great way to make this oscilloscope useful again, even if [Aaron] is already up to his gills in test equipment.