This circuit is used in VHF and UHF superheterodyne receivers. The circuit is from the 1964 RCA transistors manual. Equivalent transistors such as the BF495 can be used.
This circuit can function as a light alarm by changing the sound when light falls on the sensor....
Based on a unijunction transistor, this circuit was found in the January 1994 issue of Electronics Now...
Although it is a common configuration today, these circuits were taken from an old publication. The...