https://www.hi-fi.ru/audioportal/topic/5978-stabilizatory-nakala/page/

http://www.bartola.co.uk/valves/dht-filament-regulator/

Регулятор накала Рода Колемана (Rod Coleman DHT Filament Regulator):
http://lyrima.co.uk/dhtreg/dhtRegIntro.html