This circuit was found in a 90s Popular Electronics. The circuit operates in the range determined by L1. The integrated circuit used is uncommon today.
This powerful amplifier was part of commercial sound circuits from the 90s. The integrated circuit...
This circuit generates a control tone that serves to adjust amplifiers, check audio cables. The...
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...