3 4 c m
40cm
actual image size: 32cm x 26cm
Description
By the 1920s valves were effective amplifiers and could be used in the home to drive loudspeakers. This amplifier gave out as much power as a modern transistor radio. Printed circuit boards are composed of an electronic circuit based on thin strips of a conductor on an insulating board, made by etching.
Image Details
Image Ref.
10325997
© Science Museum / Science & Society Picture Library