This crystal oscillator generates a 20 MHz signal. Equivalent transistors such as BF494 and 2N2222 can be used. The stabilizing diodes can be 1N4148.
We found this simple shortwave receiver in an Electronics Now from the 1990s. Details of the coil...
This circuit is from 1990 documentation. When we press D1 the lamp remains on for a time interval that...
The circuit shown in figure 1 serves to control a servo motor with a current of up to 200 mA. The...