This circuit aims to increase the selectivity of receivers whose FI is 455 kHz. The circuit is from 1975 documentation. The transistors can be the modern BF494 equivalents.
This circuit generates a control tone that serves to adjust amplifiers, check audio cables. The...
This circuit is suggested by Texas Instruments and is based on a relaxation oscillator with...
This is a traditional configuration of a series regulator with zeners, found in a documentation from the...