In comparison with a contemporary MP3 participant, which is totally digital all the best way all the way down to the storage, the tape decks of the previous are ridiculously sophisticated. When the Compact Cassette (the usual “cassette tape”) first got here to market within the Nineteen Sixties, digital audio was nonetheless a pipe dream. Appropriate analog-to-digital conversion was nearby, however inexpensive storage wasn’t. So, the general public turned to cassettes tapes with their complicated electromechanical recorders and gamers. As a result of he appears to be some type of masochist, Igor Brichkov is on a quest to construct his personal DIY tape recorder/participant.
As a result of he nonetheless has some regard for his personal sanity, Brichkov appears to be focusing solely on the electrical and digital circuits. He isn’t trying to recreate the assorted winding mechanisms. That’s in all probability for one of the best, as a result of these mechanisms are notoriously temperamental — even in manufacturing tape decks. As a substitute, Brichkov is utilizing the mechanisms from an outdated tape together with his personal digital circuits.
These circuits broadly match into two classes: playback and recording. On a manufacturing tape deck, there would seemingly be extra intermingling between these with the intention to minimize prices. However on this case, Brichkov stored them largely separate and simpler to know.
The 2 most necessary parts listed here are the recording head and the playback head. Brichkov selected to salvage the playback head from an present tape deck, however constructed his personal recording head. That’s basically simply an electromagnet. As voltage from the audio supply sign passes by means of, the recording head produces a magnetic area that varies in the identical means. Run a magnetic storage medium, like tape, close by and it’ll obtain a magnetic imprint of the audio. The playback head then does the identical factor in reverse to breed the audio.
Whereas that idea is straightforward to know, the precise execution required a deep dive into analog sign processing. Brichkov relied on op-amps as pre-amps to extend the amplitude to one thing usable, however he additionally needed to embody options like AC bias mixing with the enter sign. That’s along with the recording and erasing options, in addition to a VU meter made up of eight LEDs to supply rudimentary stage visualization.
Brichkov feeds the pre-amp output on to a wired amplifier, however he linked a Bluetooth receiver module to the enter aspect. That lets him ship an audio sign from a smartphone or pill for recording. The parts are nonetheless on strip boards, however we’ll be all for seeing the place Brichkov takes the challenge from right here.