The first commercially successful record changer was the "Automatic Orthophonic" model by the Victor Talking Machine Company, which was launched in the USA in 1927. On a conventional gramophone or phonograph, the limited playing time of 78 rpm gramophone records meant that listeners had to get up to change records at regular intervals. The Automatic Orthophonic allowed the listener to load a stack of several records into the machine, which would then be automatically played in sequence, providing a long uninterrupted listening session.
Record changers were provided in most mid-priced consumer record players of the 1950s through 1970s. Record changers became rarer in the 1980s, mainly due to the introduction of the compact disc.
Some, including the changer pictured, used a variable size sensor which allowed sizes other than the three standard sizes to be played. (Note that the pictured changer has four sizes loaded.) The more basic models required the record diameter to be set manually, and hence did not allow records of different sizes to be stacked together.
Record changers were met with disdain by audiophiles because of the compromised fidelity resulting from changes in tone arm angle with the height of the stack, and concerns about changers' seemingly rough treatment of discs, particularly slight but cumulative damage to the spindle hole, as the records were effectively dropped from a height of a few inches onto the record platter. More advanced changers, such as the TD-224 model from Thorens, went some way towards addressing these problems.
The numbering of the sides of the discs in many double and triple albums (and boxed sets of LPs and 78s) is explained by the fact that they were designed to be played on record changers. After the discs were stacked and one side of each disc played, the entire stack would be turned over as a complete unit and replaced on the changer. Thus, to be heard in the proper sequence, the discs of a four-disc set would contain, respectively, "sides" 1 & 8, 2 & 7, 3 & 6, and 4 & 5 - a practice known as "automatic sequencing", "changer sequencing", or "auto-coupling".
The above is the "drop-automatic sequence", for record changers which drop records. These record changers do not reverse the stack as they go through them. But other record changers made in the 1930s reversed the stack. These kept the stack of records on the turntable, and slid the top record to the side after playing it. A separate sequence, the "slide-automatic sequence" was made for these changers, with sides coupled 1 & 5, 2 & 6, 3 & 7, and 4 & 8. The Thorens TD-224 mentioned above also reverses the stack.
There were also some record changers which played both sides of the records. The manual sequence works with these. An example is the Markel 75.
At one time, Victor released 78 rpm record sets in all three sequences.