If you’ve ever watched ’70s-era Doctor Who or tuned into The Hitchhiker’s Guide to the Galaxy on BBC Radio, you’ve probably heard the Synthi 100. Designed by hardware engineer David Cockerell, this instrument helped define the sound of ’70s sci-fi. Produced by London’s Electronic Music Studios, the EMS company was to the European synthesizer market what Moog and ARP were to the American market. This particular Synthi 100 was housed within the Soviet Union’s Radio Melodiya, and was most famously featured in the score to Andrei Tarkovsky’s 1979 film Stalker.