This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and general purpose transistors can be used.
This integrating circuit multiplies the time that can be obtained with a 555 timer. We find it in...
This circuit was found in a 1967 Ferranti documentation. It takes the transistor to the conduction...
This circuit for receiving or transmitting low power was found in old American documentation. It is...