Magnets in Video Tape: Turning Iron Particles into Visuals
In the 1970s, VHS waged a videotape formatting war with the now defunct Betamax, much like the competition between DVD and Blu-Ray within the last decade. VHS may have won out in the end thanks to its affordability, but the format has since been pushed to the limits with today’s streaming, digital, and Blu-Ray technology.
Still, VHS technology isn’t completely obsolete –– or, at least, not yet. It’s true the last manufacturer of VCFS ceased production in 2016 after the industry sold about 750,000 units the year before. As for blank VHS tapes, you can still find them on the bottom shelf at a number of electronic stores.
While the ever-rolling train of technological revolution leads us to abandon certain products in favor of “the next best thing,” we can’t help but mourn the decline of VHS since these tapes really go the distance when it comes to creatively harnessing the power of magnetism.
How Did Your VHS Show Movies?
If you were to take apart a cassette and run your fingers through the tape, you’d find your hands covered in a dark, sooty substance made of trillions tiny magnetic particles (either iron oxide or iron-cobalt.) This substance is precisely distributed across the mylar –– the strong, flexible plastic that the tape is made from –– during the recording process. Unique patterns are created, similar to what you’ll see on the back of a credit card.
When the tape is rolling inside the VCR, it passes over an electromagnet spinning at 1,800 rpm. As this happens, the electromagnet decodes the magnetic particles on the mylar and sends them to the TV screen, where the electromagnetic signals are converted into images and sounds.
Blank Tapes: How They Worked
When tapes are manufactured, the iron particles are mixed with solvent and dispersants and painted onto the plastic before the tape is cut to size. When a videographer records, the video head inside the camera rearranges the particles based on voltages received from the video signal. Once the tape is placed in the VCR, the arrangement is interpreted as image and sound.
Magnets from Apex Magnets