This VCO with discrete components was found documentation from the 1980s. The central frequency with the indicated components is 8 kHz. A BC548 can be used for Q1.
Found in a 90s Popular Electronics, this circuit monitors an RF signal providing a DC output. The...
This circuit can be used as a shield to control the matrix flow of 100 LEDs from a single output of...
The circuit in the figure generates a high continuous voltage, on the order of 40 to 6oV under a...