This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent of BC548. Observe the relatively high supply voltage.
This circuit can be implemented with other operational amplifiers. The formulas for calculating the...
This circuit is from a 1953 publication, consisting of an AM radio with 3 germanium transistors that,...
The sensor of this circuit is a common silicon diode and it directly drives a small cooler with a...