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Historical
Background
The tunnel diode is a truly unique
semiconductor, with a number of interesting characteristics and an unusual
historical past. Developed by Leo Esaki at Sony in 1957, and made public
in 1958, the tunnel (or Esaki) diode was the first device that demonstrated
the validity of quantum physics. Very high switching speed (quantum
tunneling) and the performance attribute known as negative resistance
appeared to position the tunnel diode as the successor to the transistor
for many applications. Although several companies invested heavily in
tunnel diode development, this unique technology has found only niche
applications and since the mid 1960s has been largely seen as a
technological curiosity.
Circuit design with the tunnel diode is very challenging, due
to its unusual characteristic known as negative resistance, which is found
in only a few other obscure devices (point contact and unijunction
transistors, for example). Your GE 1N3712/TD-1 is a general purpose
device, well suited for experimentation as a very low power amplifier or
oscillator. You’ll be intrigued with this 45 year old germanium device,
which functions by the mechanism of quantum tunneling of electrons.
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