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.


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

Back to the Index Page

Main Site - The Inland Marine Radio History Archive

Complete page revision with added links - 04/16/2023

Valid HTML 4.01 Transitional