This circuit was obtained in a 1967 Electronics World. The components are still common today, the SCRs can be replaced by equivalents and the unijunction transistors the 2N2646.
For measurements between 30 and 40º C this circuit was found in the documentation of 1968. The...
This circuit was found in the ON Semiconductor's Thyristor manual of the 1980s. The high quality...
Found in an old Radio Electronics, this circuit applies to frequency meters for frequencies up to 100 MHz....