BBC PAG/1/01 portable frequency generator, 1948. Orchestral 'A' portable generator, international model. Provides a consistent musical note at an a 'A' pitch, similar to that of an oboe, at a frequency of 440 Hz. Orchestral ‘A’ Frequency Generator 1948
BBC TV tone generator, used on the BBC television programme 'Mastermind' as the end of time bleeper. Mastermind tone generator
