This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
Ordinary batteries cannot be recharged, but they can go through a process of "rejuvenation" that...
We found this basic circuit of a relaxation oscillator with unijunction transistor in a 1976...
This circuit, from a 2006 documentation, automatically controls the activation of a water pump, and...