1946 · Germanium Point-Contact Diode · Work 814 of 1,871
A small diode of 1946 lying on the glass counter of a radio parts shop in a small American town, a slender plain white glass body six millimetres thick, smooth and unmarked, with bright metal end caps and a long thin wire from each end, the whole about nine centimetres from wire tip to wire tip, beside it a spool of copper enamelled wire, a black Bakelite headset, a soldering iron with a wooden handle, a hand in a rolled-up shirt sleeve reaching for the diode, shelves soft in focus behind the counter, sunlight through the shop window from the right.
What it was used for
Sylvania Electric Products released the 1N34 in 1946, per the Transistor Museum card quoted in the Computer History Museum catalogue entry as a general-purpose diode and radio detector in a white ceramic cartridge. The Transistor Museum names the classic crystal-diode medium-wave receiver as an example application and calls the part a general-purpose diode for commercial and hobbyist use. Radio-Craft of March 1946 gives the 1N34 with pigtail leads an average anode current of 22.5 mA, peak currents of 60 mA and surges up to 200 mA, a peak inverse voltage of 50 volts, a capacitance of the order of 3 pF; per the article, crystal diodes in general tolerated minus 40 to plus 70 degrees Celsius.
What was new
What was characteristic was the packaging, not the principle: the germanium point contact sat fixed in a sealed cartridge with wire leads and per Radio-Craft could be soldered directly into the circuit; the radar diodes before it also had their point set at the factory, but plugged into holders and were designed for 1 or 2 mA, whereas the 1N34 was electrically much more rugged. Per Radio-Craft of 1946 the 1N34 worked up to 500 MHz; its capacitance, per the article, was several times lower than that of a conventional vacuum-tube diode. The barb: the type number outlived its construction. The Transistor Museum credits the 1N34 with the longest continuous production history of any germanium device type and states that other firms copied it and still make it in different case styles; yet per prc68.com the 1N34 in the DO-35 glass package is not a point contact at all.
What the sources leave open: None of the sources opened gives sales figures or prices; the Transistor Museum states only "Common (Large Scale Commercial Use)". The description "first commercial germanium diode" appears on the Transistor Museum card quoted in the CHM catalogue entry and in the Transistor Museum's own texts, so from a single hand, not in a 1946 maker's publication.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.