This circuit was obtained in an American documentation from the 80's. The transistors can be equivalent to those indicated and the crystal can reach a few tens of megahertz.
This circuit was found in Linear Circuits Applications of Texas Instruments, originally using the...
This circuit, from a 1988 publication, consists of a timer that activates a relay at the end of a...
This configuration was found in the Texas Instruments optoelectronics manual. PNP transistors...