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 1967 Electronics World circuit is suitable for frequencies up to 1 MHz. The setting applies...
This circuit allows linear brightness control of an LED from an input voltage. The power supply must...
This circuit was obtained from my Mechatronics Sourcebook, published in the United States. In it...