The Open Hardware Driver For CRTs

driverCRTs are the king of displays for any homebrew project. They have everything – high voltages, high vacuums, X-rays, and the potential for a vector display – that makes a project exude cool. Getting an old CRT up and running, though, that’s another story. Never rear, because now there’s an Open Hardware eletrostatic CRT driver for your next display.

[Eric] designed a driver circuit that should be able to send a picture to most 2″, 3″ and some 5″ electrostatic CRTs, the kind found in ancient TVs and oscilloscopes. The 1kV power supply uses a transformer usually found in a CCFL bulb, and is able to produce several milliamps. You’ll want to keep one hand behind your back when working on this.

The driver circuit takes a 0-3.3V analog signal for deflecting the beam along the X and Y axis. The amplifier has enough bandwidth to handle NTSC video, so displaying video along with vector letters and shapes is also a possibility with this circuit. Most of the files are available on the git, with three boards available to be ordered from OSHPark.
Thanks [Mike] for the tip.

23 thoughts on “The Open Hardware Driver For CRTs

  1. i have not read the full article but CCFL transformers are generally not designed to run at full voltage continuously but start in a few KV then drop to a few hundred volts, but i mean if it works it works!

    1. The only thing we have to fear, is rear itself. Or is it the only thing we have to rear, is fear itself?

      Fear was just a young beastie, being reared by his godparents Phobos and Deimos, when he met Harry Dresden…

    2. “…Rear is the mind-killer. Rear is the little-death that brings total obliteration. I will face my rear. I will permit it to pass over me and through me… Where the rear has gone there will be nothing….only I will remain.”

  2. This is actually a damn sweet hack. I have a few small CRT’s lying around and have occasionally thought of purposing them. If these boards were available assembled or as a kit I’d be whipping out the plastic. I may yet order a set of boards since the self-kit from mouser is a possibility, but I’ll have to take a closer look since I’ve got a lot of other stuff going on.

  3. Would this deflection-board be suitable to convert a 37cm (about 15 inch) TV to a XY monitor? I’m trying to create a monitor for my old Asteroids board :). The old HV and everything on the TV is intact.

    1. No, Those picture tubes use magnetic diflection with coils wrapped around the neck of the tube, this circuit looks like its designed for electrostatic tubes that have plates built into the neck instead.

    2. The old Asteroids game used a monitor that is very similar to a TV. The monitor was more or less a TV with lots of parts missing. If you talk to an old technician then he/she will be able to convert a TV for you.

      Be warned though that even a small 15″ screen has a HV drive of 14,000 Volts to 17,000 Volts. That’s more than enough for electrocution. Electrocution being the ‘fatal’ version of electric shock.

      Also there are still many retro arcade web sites that will sell you a monitor.

      1. Well, I just did a lot of googling and I was wrong.

        The vertical deflection bandwidth of a TV is far too low to be used as a vector display.

        Converting a TV would require rewinding of the vertical deflection yoke and co-responding changes to the drive circuitry. It is NOT a simple conversion as I previously thought.

  4. Nice design, but I’ll pass.

    I’m not into retro or steampunk, so I’d rather ewaste those old heat generators and use either a nice juice sipping LCD/OLED or better yet, why do I need numerous displays, just pipe the info to my smartphone.

    CRT’s are oh so last century, and although they exude something, I’m pretty sure it’s not cool. YMMV.

    1. Yeah, MMV.

      CRT hacks are not about presenting information. They are about putting on display something functional and elegant. Yes, junior, we all have smartphones and I could use mine as an alarm clock if I needed to. But I built one with Nixie tubes because it has a three dimensional presence modern displays don’t, and it’s a very cool thing you don’t have.

  5. Quote: ‘[Eric] designed a driver circuit that should be able to send a picture to most 2″, 3″ and some 5″ electrostatic CRTs, the kind found in ancient TVs and oscilloscopes’

    Um, oscilloscopes yes, TV’s no!

    Electrostatic deflection is build into the tube (CRT). TV’s are electromagnetic deflection and can’t be modified for electrostatic deflection.

    All is not lost, there are plenty of old oscilloscopes around and sometimes you even find just the tube on offer.

    TV’s have a horizontal scan rate (approximate bandwidth) of about 16Khz and a vertical scan rate of 50 – 60 Hz, electromagnetic deflection is fine for these low frequencies.

    Oscilloscopes have horizontal and vertical deflection rates of 10’s of MHz, this is far too high a frequency for electromagnetic deflection so electrostatic defection is used.

  6. “You’ll want to keep one hand behind your back when working on this.”

    Or even in you pocket. In case of shock, electricity will go directly into your legs instead of your torso.

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