Demystifying Camcorder CRT Viewfinders

November 14, 2012 by 58 Comments

Every smartphone (and most dumb phones) has a video camera built into it these days. Some of them are even capable of recording respectable HD video. So we’d bet that the decades old camcorder you’ve got kicking around isn’t getting any use at all anymore. [John] wants to encourage you to hack that hardware. He published a post showing just how easy it is to salvage and use a camcorder CRT.

The gist is that you simply need to hook up power and feed it video. The board that is attached to the CRT has its own voltage hardware to drive the tube. He demonstrates a 9V battery as a power supply, but also mentions that it should be pretty easy to power the thing from a USB port. As for video, all it takes is a composite signal. Of course you’ve got to determine the pinout for your particular CRT module. The method he chose was to use a continuity tester to find the path from a capacitor’s negative leg to the appropriate pin header. Next he used a bench supply to inject a current-limited low voltage until he saw response when probing the pins. Finding the composite-in is a similar trial and error process.

So what can you use this for? Why not make it the display for a simple video game?

Spinning CRT Makes A 360 Degree Audio Oscilloscope

September 16, 2023 by 9 Comments

A question for you: if the cathode ray tube had never been invented, what would an oscilloscope look like? We’re not sure ourselves, but it seems like something similar to this mechanical tachyscope display might worked, at least up to a point.

What’s ironic about this scenario is that the tachyscope [Daniel Ross] built actually uses a CRT from a defunct camcorder viewfinder as the light-up bit of what amounts to a large POV display. The CRT’s horizontal coil is disconnected while the vertical coil is attached to the output of a TEA205B audio amplifier. The CRT, its drive electronics, and the amp are mounted to a motorized plastic platter along with a wireless baby monitor, to send audio to the CRT without the need for slip rings — although a Bluetooth module appears to be used for that job in the video below.

Speaking of slip rings, you’d expect one to make an appearance here to transfer power to the platter. [Daniel] used a slip ring for his previous steampunk tachyscope, but this time out he chose a hand-wound air core transformer, with a stationary primary coil and secondary coil mounted on the platter. With a MOSFET exciter on the primary and a bridge rectifier on the secondary, he’s able to get the 12 volts needed to power everything on the platform.

Like most POV displays, this one probably looks better in person than it does in video. But it’s still pretty cool, with the audio waveforms sort of floating in midair as the CRT whizzes around. [Daniel] obviously put a lot of work into this, not least with the balancing necessary to get this running smoothly, so hats off for the effort.

Continue reading “Spinning CRT Makes A 360 Degree Audio Oscilloscope” →

A tiny CRT showing an eye, inside a plexiglass enclosure

This Eye Is Watching You From Its Tiny CRT

October 9, 2022 by 25 Comments

The days of cathode ray tubes, or CRTs, are firmly behind us, and that’s generally a good thing. Display tubes were heavy, bulky and fragile, and needed complicated high-voltage electronics in order to work. But not all of them were actually large: miniature display tubes were also produced, for things like camcorder viewfinders, and [Tavis] from Sideburn Studios decided to turn one of those into a slightly creepy art project.

The heart of this build is a one-inch CRT that was salvaged from an RCA video camera. [Tavis] mounted the tiny tube inside an acrylic box on a 3D printed base. Inside that base sits a Raspberry Pi along with a high-voltage driver and a power management board. The Pi continuously plays a video that shows a human eye blinking and looking in various directions. Just an eye, floating in space, looking at the world around it.

The magic is briefly lost when the Pi starts up, because it then shows a microscopic version of the Pi’s standard bootup sequence, but once the thing is running it adds a weird vibe to a room. It actually looks like something you’d find in an avant-garde art exhibition — in the video (embedded below) it’s accompanied by eerie music that gives it an even more unsettling feel. Electronic eyes are always a bit scary, especially when they’re actually looking at you.

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Tiny TV Celebrates The Forgotten Tech Of CRTs

February 11, 2022 by 35 Comments

For those of us who grew up before the Internet, the center of pretty much every house was the TV. It was the shrine before which we all worshipped, gathering together at the appointed times to receive the shared wisdom of mass entertainment. In retrospect, it really wasn’t that much. But it’s what we had.

Content aside, one thing all these glowing boxes had in common was that which did the glowing — the cathode ray tube (CRT). Celebrating the marvel of engineering that the CRT represents is the idea behind [Matt Evan]’s tiny desktop TV. The design centers around a 1.5″ CRT that once served as a viewfinder on a 1980s-vintage Sony camcorder. [Matt] salvaged the tube and the two PCB assemblies that drive it, mounting everything in a custom-built acrylic case, the better to show off the bulky but beautiful tube.

The viewfinder originally used a mirror to make the optical path more compact; this forced [Matt] to adapt the circuit to un-reverse the image for direct viewing. Rather than receiving analog signals off the air as we did in the old days — and we liked it that way! — the mini monitor gets its video from a Raspberry Pi, which is set to play clips of TV shows from [Matt]’s youth. Rendered in glorious black and white and nearly needing a magnifying glass to see, it almost recaptures the very earliest days of television broadcasting, when TVs all had screens that looked more like oscilloscope CRTs.

This project is a nice homage to a dying technology, and [Matt] says it has spurred more than one conversation from people you grew up knowing only LCD displays. That’s not to say CRTs are totally dead — if you want to build your own old-school TV, there’s a kit for that.

A Retro Camcorder Upgraded As A Raspberry Pi HQ Camera

December 5, 2020 by 14 Comments

In 2020 when we carry an all-purpose computer and data terminal able to store our every thought and deed on a global computer network, it’s easy to forget that once upon a time we were excited by the simpler things. Take the camcorder for example, back in the 1990s the idea of a complete video recording solution that captured moving images on tape cartridges and fit in the palm of your hand was a very big deal indeed, and camcorders as we called them in those innocent times were a prized posession. Now they’re a $0.50 find a Goodwill, which is how [Dustin] picked up the RCA camcoder he’s converting into something altogether more modern. He’s gutted it and upgraded it by removing the analogue innards and retaining only the case and lens assembly to put around a Raspberry Pi and associated HQ camera module.

Opening the camcorder up reveals a ton of miniaturised analogue circuitry, but once the original assemblies are removed it’s relatively straightforward to put the Pi camera on the rear of the lens unit. There’s plenty of space for the Pi in the box, and he’s putting a touchscreen on the outside.

Sadly the camcorder’s original tiny CRT is no longer working, else that would have been the ultimate retro viewfinder. Still we hope to see some tinkering on that part of the project since those little CRTS make for delightful hacks. The project is very much a work in progress, but should serve that these once ubiquitous devices are now in the realm of the throwaway.

This isn’t the first such conversion we’ve seen with a Raspberry Pi, the original camera module is a handy fit to an 8mm movie camera.

Recording Video In The Era Of CRTs: The Video Camera Tube

February 27, 2020 by 45 Comments

We have all watched videos of concerts and events dating back to the 1950s, but probably never really wondered how this was done. After all, recording moving images on film had been done since the late 19th century. Surely this is how it continued to be done until the invention of CCD image sensors in the 1980s? Nope.

Although film was still commonly used into the 1980s, with movies and even entire television series such as Star Trek: The Next Generation being recorded on film, the main weakness of film is the need to move the physical film around. Imagine the live video feed from the Moon in 1969 if only film-based video recorders had been a thing.

Let’s look at the video camera tube: the almost forgotten technology that enabled the broadcasting industry. Continue reading “Recording Video In The Era Of CRTs: The Video Camera Tube” →

A Pair Of CRTs Drive This Virtual Reality Headset

January 23, 2020 by 12 Comments

With the benefit of decades of advances in miniaturization, looking back at the devices of yore can be entertaining. Take camcorders; did we really walk around with these massive devices resting on our shoulders just to record the family trip to Disneyworld? We did, but even if those days are long gone, the hardware remains for the picking in closets and at thrift stores.

Those camcorders can be turned into cool things such as this CRT-based virtual reality headset. [Andy West] removed the viewfinders from a pair of defunct Panasonic camcorders from slightly after the “Reggievision” era, leaving their housings and optics as intact as possible. He reverse-engineered the connections and hooked up the composite video inputs to HDMI-to-composite converters, which connect to the dual HDMI ports on a Raspberry Pi 4. An LM303DLHC accelerometer provides head tracking, and everything is mounted to a bodged headset designed to use a phone for VR. The final build is surprisingly neat for the number of thick cables and large components used, and it bears a passing resemblance to one of those targeting helmets attack helicopter pilots use.

The software is an amalgam of whatever works – Three.js for browser-based 3D animation, some off-the-shelf drivers for the accelerometers, and Python and shell scripts to glue it all together. The video below shows the build and a demo; we don’t get the benefit of seeing what [Andy] is seeing in glorious monochrome SD, but he seems suitably impressed. As are we.

We’ve seen an uptick in projects using CRT viewfinders lately, including this tiny vector display. Time to scour those thrift stores before all the old camcorders are snapped up.

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