The Philips EL 3583 was an office dictation machine that used small cartridges of ⅛-inch tape. It appears to have been introduced around 1963, around the same time that Philips also introduced their Compact Cassette system, and it may have replaced the EL 3581 system.
The threading mechanism was unusual; a supply cartridge and a separate take-up cartridge would be placed in the machine and lever would be depressed causing a latch at the end of the supply cartridge’s tape to be pulled across and to lock into the take-up spool.
Like other dictation machines, the microphone also acted as a small speaker and contained a control to begin recording.
It’s unclear when the system was produced until, but it seems unlikely to be much beyond the early 1970s as Philips own Compact Cassette and mini-cassette designs, as well as other competing cassettes such as the Microcassette were available.