A Volume Control From A VCR Drum

The VHS VCR has now passed from widespread use, and can thus be found as a ready supply of interesting parts for the curious hardware hacker. [Clewsy] has a novel use for a VCR head scanning drum, the part that is supposed to be tasked with reading information off of magnetic tape. Instead, it’s reading information from fingers as the knob for a USB volume control. Underneath the drum is an optical encoder disk which is read by an ATmega32U4 for USB interfacing with a host computer.

The helical-scan video recorder was a mechanically complex solution to the problem of recording a high-bandwidth video signal onto a tape that could be made slow-moving enough to be practical. By recording the video in diagonal stripes across the tape from a fast-moving spinning head they avoided the need for huge reels of tape, enabling hours of video to be fitted into a roughly book-size cassette.

While over time the mechanics of a VCR mechanism were simplified and cheapened to a great extent, the heads and drum were the one area that could not be compromised. Thus the VCR head was for a time the most high-precision mechanical device owned by most consumers, and the drums usually have exceptionally nice bearings. All of this makes one a particularly good choice for a volume knob or indeed any other large rotational control, so much so that we’re surprised it hasn’t become a more frequent occurrence. So scour the electronic junk, and you might just find the ultimate in free high quality control hardware.

Of course, this isn’t the only thing a VCR head drum can do.  How about a centrifuge?

Retrotechtacular: Home Video Recording

The news has been full of reports that the last company manufacturing consumer VCRs will cease making them this year. I think most of us are surprised that the event is only happening now. After all, these days, video recording is likely to be on a hard drive, a USB stick, or on a server somewhere. Even recording to DVDs seems a bit quaint these days.

VCR-03Back before there were web sites, people had to get information from magazines like Popular Electronics, Radio Electronics, and a few others. In the late 1960s and early 1970s, it was common to see these magazines predict that this would be the year of the home video recording system. For example, in 1971, [Lou Garner] wrote: “…they [Sony] hope will put home videotape playing in the same living room as conventional high-fidelity sound systems.” You should know that the video cassette he was talking about was 8 inches wide by 5 inches deep (a big larger than a VHS tape) and contained 3/4 inch magnetic tape (VHS used 1/2 inch tape). The 32-pound player had a retail price of about $350 (about $2,000 in today’s dollars; remember gas was $0.36 a gallon and eggs were $0.53 a dozen). It would be several years before VHS and Betamax would duke it out for home supremacy.

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VCR Centrifuge

VCR’s practically scream “tear me open!” with all those shiny, moving parts and a minimal risk that you’re going to damage a piece of equipment that someone actually cares about. Once you’ve broken in, why not hack it into a centrifuge like [Kymyst]? Separating water from the denser stuff doesn’t require lab-grade equipment. As [Kymyst] explains: you can get a force of 10 G just spinning something around your head. By harvesting some belt drives from a few VCR’s, however, he built this safer, arm-preserving motor-driven device.

[Kymst] dissected the video head rotor and cassette motor drive down to a bare minimum of parts which were reassembled in a stack. A bored-out old CD was attached beneath the rotor while a large plastic bowl was bolted onto the CD. The bowl–here a microwave cooking cover–acts as a protective barrier against the tubes spinning inside. The tube carriers consist of plastic irrigation tubing fitted with a homemade trunnion, which [Kymyst] fashioned from some self-tapping screws and a piece of PVC. At 250 rpm, this centrifuge reaches around 6 G and best of all, gives a VCR something to do again. Take a look at his guide and make your own, particularly if your hackerspace has a bio lab.

Hackaday Links: September 1, 2013

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[Anton] has been doing some Commodore 64 Datasette experiments. He managed to connect the C64 audio traces to his smartphone and use it for tape playback.

Not wanting to actually disassemble his Mendel 3D printer, [SteveDC] figured out how to make extenders that increase his build height by about 40%.

We have fond memories of owning an 8088 PC. We did a lot of experimental programming on it but never anything as impressive as getting the TCP/IP stack to run on it. Then again, we’re not sure there was such a thing back when we owned the 10 MHz hardware. That’s right, the microcontrollers we mess around with now days are much faster than that old beast was.

When he goes running at night [Tall-drinks] straps a pico projector to his chest. We guess you’d call the readout a heads-up display… but it’s really more heads-down since it’s projecting on the pavement.

See how things heat up as a Raspberry Pi boots. This video was made using a thermal imaging camera to help diagnose a misbehaving board.

We don’t have very many trinkets on our desk (that would steal space normally reserved for clutter). But be would happily make room for this motorcycle model made from VCR parts (translated).

Pan/Tilt Wheel Trainer Ends Up Being A Different Way To Play Quake

This is a special controller that [Gary Scott] built to help train camera operators. The pan and tilt controls on high-end movie cameras use wheels to pan and tilt smoothly. This rig can be built rather inexpensively and used to practice following a subject as you would with a camera. This is where the project takes a turn into familiar territory. [Gary] set up a system so that you can play the game Quake using this controller, with your feet doing the rest.

The pan/tilt controller uses two heads from an old VCR. They are mounted above the guts from an old ball-type mouse. A couple of rubber belts connect the heads to the two mouse bars that are normally rotated by the ball. This gives him control of where the Quake game is looking. But he still needed to be able to move, jump, change weapons. and shoot. So he built a second controller for his feet. It uses a CD and some switches as a joystick, and a set of buttons for the other controls. He actually rigged up solenoids to each of those foot switches to physically press keys on a keyboard. You really must see it for yourself. We’ve embedded his set of videos after the break.

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Classical VCR Head Jog Wheel

[Osgeld] takes on the classic VCR head jog wheel in this instructable. He has done a fantastic job not only in his build quality, but in the quality of the writeup. As he points out, the idea of using the head as a jog wheel isn’t new. His construction and build quality however have yielded a fantastic looking reliable device that we would be proud to have sitting on our desk.

As usual, the most interesting bits of the writeup are how he solved problems he encountered. For example, he’s using an optical mouse to detect the motion of the wheel. This requires that he print out a pattern to mount opposite the optical sensor. This sounds straight forward enough, but he found the results to be less than stellar. He documented his fix, basically reworking it in GIMP, so others can save some time. That is how tutorials should be. Great job [Osgeld].

Rotary Display Uses VCR Head And LEDs

[Daniel Daigle] is developing a rotary display that uses persistence of vision to graph data. The hardware he used includes a spinning head from a VCR, some LEDs, and a timing circuit to display 360 degrees of data. His timing input uses a waveform so this will work with any application where you can generate a PWM signal.

Check out his videos after the break that demonstrate a graph with a single line and another with six display lines.

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