Sony TC-50
This is the Sony TC-50 cassette recorder. This unit came out in 1968, and was the smallest cassette machine produced at the time.
This model is famous as it was the model chosen by NASA to be taken aboard the command module of the Apollo moon missions.
There is a strong possibility this unit has actually been used by NASA, but not apparent in the pictures. The units used by the Apollo program (there was more than one) had a metal sticker on the front with operating instructions, as well as a special serial number stamped. The jacks were taped to make then unuseable. Velcro was affixed to the rear of the unit to facilitate the machine being stuck to the wall in the microgravity environment.
I have acquired two TC-50's. One was found at an estate sale back in 2007 or so. It was in very good cosmetic condition, but the motor had a problem that I made worse when trying to fix (it was my first attempt at a TC-50 repair). Later in 2013, I went to a now out-of-business place called "The Black Hole" in Los Alamos, New Mexico.
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IBM "Magnabelt" Recorder
This is a very strange recording machine indeed. Imagine a phonograph like with Edison. Yet instead of a cylinder you have a loop of magnetic tape. Instead of a cutting stylus, you have a record/playback head. The head glides across the width of the tape slowly as the tape moves, making one long, continuous spiral-shaped track.
This unit even has a "tuning" control with adjusts the alignment of the head with the track. This unit was repaired back in 2014 after getting it on eBay. The original (geared) belt was long gone, and the gear that turned the magnabelt was even cracked if I remember correctly. Luckily, I found a similarly-sized pully wheel (from a gutted VCR or something) and affixed it where the gear-shaped wheel was, and replaced the belt with a round (cross-section) belt, and the unit functions again. Yet, the battery was another issue. The unit used special IBM proprietary (does IBM just LOVE proprietary things?!) 12V mercury battery. No new replacements for that, that's for sure. So I gutted a couple of 9V PP3 batteries and got the AAAA cells out, wired 8 in series, wrapped them in electrical tape and fitted them in the battery compartment. The unit came to life. But later, the cells prematurely corroded, as tends to be the way of the AAAA cells from the 9V batteries in my experience. They have since been removed from the machine.
Also, from what I can gather, this unit is DC bias. It is best to bulk-erase the belt before recording over, although it does erase while recording.
A very fun recorder to use, though it has been a while (batteries and laziness).