Found in Popular Electronics from the 90s, this circuit generates signals in a frequency range set to R7 and basically determined by C1. Operational and equivalent transistors can be used.
This circuit was found in an Electronics World of 1968. It can be applied to any modern triac and...
This circuit is from a documentation from the 70s. The transistors are types of germanium of the...
Obtained from a 1996 documentation, this circuit uses common components and has a voltage gain of 200...