?Final Price Realized includes Buyer’s Premium added to Hammer Price
Estimate: $ 3,500 - $ 5,000
EXPERIMENTING IN VACUUM TUBE AMPLIFICATION EDISON, THOMAS A. Two graphite drawings, unsigned, on a single sheet, each a schematic diagram showing a vacuum tube amplifier in a device for monitoring sound, each with holograph caption ("Single take" and "2 Lamp take"), and holograph labels (e.g., "phone" indicating a speaker). The first diagram shows a circuit with a single vacuum tube, the second, positioned below the first, shows the same circuit with two tubes. 1 page, 4to, ruled paper; moderate toning overall, minor staining affecting first diagram, two punch holes in left margin, faint scattered soiling, folds. Np, [3 May 1927?]
