Mattel Synsonics drum synth. Courtesy of spheremusic.com
A drum synthesizer marketed by Mattel, the toy manufacturer, beginning in 1981. The Synsonics contained four stick-played drum pads and produced six drum sounds: two toms (one tuneable), a snare, a cymbal, a closed hi-hat, and a kick drum. All of the sound-producing circuitry was analog. Despite its origins and its somewhat toy-like appearance, the Synsonics was taken seriously in some quarters and used in some professionally produced music. It was far less expensive than competing products of the era, and many drummers in the '80s got their first exposure to electronic drumming via the Synsonics. It was battery powered, but could also be powered from an external "wall wart" supply.
The Synsonics also contained a rudimentary sequencer. For the toms, snare, cymbal and kick sounds, there were buttons that would play each sound at quarter, eight, or sixteenth note intervals, as driven by an internal clock. (The sequencer was the only way to play the kick, since it had no associated pad.) Pressing an "accent" button changed the cymbal to the closed hi-hat sound; it was not possible to make them both sound at once. The sequencer had memory for three tracks, and the pads could be used to play along when a sequence was playing. Unfortunately, the sequencer did not have any non-volatile memory, which meant that all sequences were lost each time the machine was switched off. For synchronizing the clock, the sequencer had one of the first implementations of tap tempo; if a button was pressed twice, the CPU that ran the sequencer measured the interval and used that to set the clock rate. (There was no way to synchronize to an external clock.)
Opinions on the Synsonics' sounds varied. The tom sounds were generally well regarded. Some drummers appreciated the white noise-y snare and cymbal sounds, but others regarded them as too top-ended, and the non-adjustable envelope on the snare was thought to be too long. The kick was "clicky" and not very bassy, and was downrated by most reviewers.
Kraftwerk was one of the major artists that used the Synsonics, though the extent of its use in their material is unknown. The progressive rock band Saga made a notable use of a Synsonics in a piece called "A Brief Case"; during their live shows, multi-instrumentalist Michael Sadler brought out on stage a Synsonics mounted in a road case, set it on a table, and used to play a drum duet with drummer Steve Negus (who played his part on a Simmons set). The short piece ended with Sadler slamming the case shut and carrying it off stage.
The pads were velocity sensitive and have held up surprisingly well. A five-pin DIN jack on one side appears to be a MIDI interface, but it is not (MIDI had not yet been invented); it was intended for an auxiliary pedalboard that allowed the user to control the kick drum and to open and close the high-hat. It is unclear how many units were made or when the model went out of production, but a large number are available inexpensively on the used market. Many modifications are available on the Web.