In other words, can I make a personal 8 track player with just headphones in the style of a Walkman?
How small can I make it? Bear in mind it needs quite a bit of power to move the tape loop around inside the cartridge.
Before anyone asks what the point is, it is to see if I can do it, just like most other things I make. I accept this one is only of super-niche interest.
A couple of years ago I bought a really cool "Lear-Jet" 8 track tape cartridge player and got it working for an old car. These preceded cassette players and were unusual in that the tape runs in a continuous loop - you cannot fast-forward or rewind them like a cassette. They were the first usable in-car entertaiment device and sold mainly in the US. After doing more research I found out more:
a) The cartridges had reputation for jamming and sticking. However the internal mechanisms can usually be restored to work properly.
b) The tape moves much faster past the tape head than in the later cassette tapes. This is so the "hiss" becomes higher frequency than you can hear, necessary as Dolby hiss reduction did not come along until later.
c) Therefore, with a high-end 1970's indoor HiFi player, the sound quality can actually be very good.
d) No matter how old they are (1970's and early 80's) the actual tape itself does not degrade much. I have some that sound stunningly good against all expectations.
e) I like 70's rock!
I would recommend younger viewers to read around this subject, the history of the 8 Track player is an adventure in itself featuring people such as William Lear of Lear-Jet fame and "Mad-Man" Muntz, an early affordable TV pioneer in the US.
Everything you may want to know can be found on these pages, especially the first one: