Semiconductor Oddities - Negative Resistance
Semiconductors can be used, connected or combined in unusual ways to produce different characteristics or modes of operation or can even be made DIY using unusual materials. I have experimented with transistor simulations of the Lambda diode (negative resistance) and with other types of compound-connected devices, and have collected considerable information on this topic. This page unifies that information. On-site PDFs noted.
A
compound connection
of one sort or another is the key to using bipolar and FET
transistors in various combinations to simulate other
semiconductors and to produce other devices or unusual
effects. Lambda
diode, Darlington, Sziklai, negative resistance, tunnel diode,
unijunction transistor, etc. are some of the words often associated
with the results of these compound connections. The use of
a bipolar transistor with shorted or open connections to
produce a diode is another unique way of
using
transistors. Perhaps the strangest of all is the use
of the galvanic couplings of materials, not generally considered as semiconductor materials, to make semiconductors.
Diodes:
Wideband
RF noise generator - a diode and
4 parts
Wideband RF noise
generator - a transistor junction and 5 parts - VK1BL
A
Crystal Diode Noise Generator - From 73 Magazine - W5TEV
The Diode Connected Transistor - Short Base to Collector
Compound connections - Darlington, Sziklai, Cascode etc:
Bipolar-FET Parings - PDF - 4 combinations with characteristic curves - Great article
Wikipedia
on Darlington compound connection
Wikipedia
on Sziklai compound connection
Wikipedia
on the Cascode connection
FET Cascode Combination - PDF
Darlington-Sziklai
Tutorial
Sziklai
vs. Darlington
Darlington
& Sziklai pairs
Sziklai
connection
Darlington
connection
Temperature Stabilized Darlington - PDF
DIY Dual Gate FET - Hot Iron #91 - Pages 2-4
Tunnel Diodes, Lamba diodes & Negative resistance:
Tunnel Diodes From 73 Magazine - K8TSQ
Lost
in a Tunnel From 73 Magazine - K5JKX
Wikipedia
on the Lambda diode
Three DIY Negative Resistance Circuits - PDF
Lambda Diode with FETs - Incomplete Article
Negative
Resistance Revived - VK5BR
DIY Lambda Diode - PDF - WB5DEP
A
Dip Meter Using the Lambda Negative
Resistance Circuit - VK5BR
More
on Negtive Resistance Including a
Regenerative Receiver - Ramon Vargas-Patron
Unijunction Transistors - UJTs
The
Unijunction Transistor - From 73 Magazine - VK3ZRY
DIY Unijunction Transistor - PDF - Make a Unijunction using 2 Bipolar Qs
DIY semiconductors:
Make semiconductors with unusual materials and put them to work - A fascinating site
Of course there's more about this topic - Have anything to contribute?
Contact Me
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Complete page revision with added links - 04/16/2023