This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s Electronics Now. The circuit has an active filter. Modern equivalent transistors can be used.
Pressing S1 the LED glows by a time interval depending on the capacitor. Time intervals in the...
This overtone oscillator can generate signals up to 150 MHz. The crystal determines the frequency and...
Found in a 90's EDN, this circuit generates signals in the frequency range given by the graph. The...