Hello Gravis! I thought of a weird thing, and its PROBABLY useless, but I was wondering if it was possible at all.
I like watching stuff on my old CRT, VHS and DVD and such. I also have used a casette Bluetooth/aux adapter, which is kinda like this actual cassette tape-looking device, that somehow converts the audio into an electromagnet which tricks the player into thinking that there's a tape.
Is it possible to do something similar with a VHS tape? Could there be like a "flash cart" VHS, maybe with a screen to select files from an SD card on it before inserting into the VCR? Would this kind of thing even be possinle?
I hope this question isnt too weird hahaa. Its SUPER impractical too, since those little video players exist, and even output via RCA, but I thought it would be a fun idea for an ask!
Great question!
ABSOLUTELY NOT. STRONG LETTER TO FOLLOW
The short answer is that VCRs are phenomenally complex compared to tape decks, so it's sort of like trying to start a nuclear reactor with a lawnmower pullrope - but I figure you might want some details!
I will try to keep this concise because it can be easy to get lost in the mechanics of it.
Video is OBSCENELY high-bandwidth compared to audio. You can fit decent-quality audio into a magnetic trace only a 32nd of an inch wide, with the tape moving at only a couple inches per second. Video cannot do this; we're talking 22 kilohertz versus six megahertz, it's literally orders of magnitude more information.
Thus, to record video magnetically, you need to move the tape past the head at something like several dozen feet per second. They tried this in the 50s; it barely worked and it ate tape at a completely impractical speed, it was totally out of the question.
The solutoin, which all successful videotape formats ever made use, is a helical scanning technique (except for quadruplex, which is transverse, but let's not get into that.) Basically, the tape is wrapped around a cylinder that contains the read/write heads, and instead of moving the tape at high speeds, the head spins against the tape at a couple thousand RPM.
From the head's perspective, the tape is moving past it at several feet per second, so it can get the necessary bandwidth. The head is also rotated relative to the tape, so instead of writing the signal along its length, it writes it in a series of stripes at an obtuse angle.
That can be hard to visualize. Here's what matters:
The reason the cassette audio adapter works is because the bandwidth is low and the head is stationary. The cassette simply contains an ordinary tape deck head, and when you put it into your tape player, the electromagnetic coil in the cassette is mashed up against the matching coil on the player. When you feed audio into it, it's simply coupled (inductively, right...?) into the coil in the player, and interpreted as audio. The heads never perfectly meet, and they aren't matched very well, so the quality of the sound is never that hot or consistent, but who cares, it's good enough.
Doing this with VHS is impossible for a whole host of reasons, but the simplest is just that you can't make an electromagnet that's shaped like the path the head would trace on the tape. You would need to somehow create a coil that's something like... 4 or 5 inches long? And that coil would need to be able to transmit a 6MHz signal without significant degradation, while also being flexible enough to get pulled into the deck and wrapped around the head without damage or misalignment.
As far as I know this is something you'd need a NASA research team and eighteen months to pull off, if it's even physically possible. Then once you're done, I think you also have to build an incredibly complex mechanical system to fake realistic tension on the capstan and reels, because VCRs are full of torque sensors and whatnot to ensure that the tape is actually moving correctly; this is less true for very old ones, but they're all busted anyway.
Here's what I recommend instead:
Buy a junker VCR and the longest VHS cassette you can get. Open up the tape and cut a hole in the bottom of the case. Glue a thin PCB in this hole, with contacts going back to some kind of gadget (exercise for the reader to build one) that plays standard-def video with analog output. Add pogo pins inside the VCR which will press against these contacts when the tape is inserted and lowered into play position; the other ends of the pins are attached to the video and audio outputs on the back. Remove the plastic window from the tape and put an LCD touchscreen in its place for selecting media.
Now you have a composite video player in a VHS form factor. You can stick it in the machine, and you'll get the satisfying motor and solenoid noises, and the whirring of a playing tape, but none of the VCR circuitry is doing anything, just playing an empty tape into the void while your digital player spits out a video signal.
It's the closest you can get to a True Aesthetic Experience, because otherwise what the VCR is doing is just fundamentally impossible to mimic; tape's properties are utterly unique.
