Category: CRTs

  • VGA display… On a 3″ scope tube!

    Yes, you’ve all thrown away your lunky old CRT monitors, in favour of sleek ultra-thin LCD displays. And, you thought you’d never see another one again…

    But this CRT display has a twist! It’s round. It’s small at just 3 inches diameter. And it’s awfully cute.

    Oscilloclock 3-inch CRT VGA Display Assembly - overview

    Last year, I was approached by a dedicated flight simulation enthusiast, who needed a radar indicator to use in a fighter cockpit replica. The indicator should employ a CRT, for the most realistic look. Could Oscilloclock design and construct such a display?

    It didn’t take much convincing! Diverging only temporarily from building clocks, I took up the challenge to create my first raster-scan CRT display unit. In the ensuing months, difficulties sprang forth from every direction in the project, but ultimately I was able to avoid a diraster (sic) and deliver a functional assembly:

    See more related videos on my YouTube channel

    The Setup

    The key component of this setup is a new prototype VGA Board that converts a VGA signal into analogue X and Y outputs. Both analogue intensity and binary blanking outputs are provided.

    Oscilloclock VGA Board prototype
    Oscilloclock VGA Board prototype

    The X and Y outputs drive an Oscilloclock Deflection Board, while the binary blanking output drives the blanking amplifier in a CRT Board. Blanking isolation, heater, and HV supplies are provided by a Power Board.

    Oscilloclock Deflection Board - modified for ultra-linear HV output
    Deflection Board – modified for ultra-linear HV output
    CRT Board - heavily modified for improved frequency response
    CRT Board – modified for improved frequency response
    Power Board - with improved optocoupler
    Power Board – with improved optocoupler

    It all looks so easy! But noooo. Astute readers will recall from other posts that every Oscilloclock project involves sleepless slumbers, horrific hair-pulling, and forgotten family members. Let’s see what caused me grief this time…

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  • The Invisible … Beam?

    One of the most exciting things you can do with a Scope Clock is to simply look at it from behind! In many CRTs, the anode coating (a conductive black surface sprayed onto the inside of the glass) doesn’t extend all the way to the screen – leaving a nice gap of clear glass from which to observe the beautiful electron beam.

    Ha – you can put down your magnifying glasses now.

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  • A colleague asked me whether the trailing effect you see on the seconds hand was a photography trick, or something actually visible to the human eye.

    Trailing effect

    Yes, the trailing effect is real, and it’s thanks to a characteristic of the CRT’s phosphor screen called persistence.

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