in the 1930s, the superheterodyne design began to gradually supplant the regenerative receiver, as tubes became far less expensive. in germany the design was still used in the millions of mass-produced german "peoples receivers" (volksempfänger) and "german small receivers" (dke, deutscher kleinempfänger). even after wwii, the regenerative design was still present in early after-war german minimal designs along the lines of the "peoples receivers" and "small receivers", dictated by lack of materials. frequently german military tubes like the "rv12p2000" were employed in such designs. there were even superheterodyne designs, which used the regenerative receiver as a combined if and demodulator with fixed regeneration. the superregenerative design was also present in early fm broadcast receivers around 1950. later it was almost completely phased out of mass production, remaining only in hobby kits, and some special applications, like gate openers.