This circuit uses a resonant reed relay to recognize the frequency of an input signal. Adaptations can be made to obtain functioning as a shield. The circuit is from 1965 documentation.
This circuit can be used on sound mixers to obtain effects. We found the circuit in a 1997...
This circuit was found in documentation from the 90s, being indicated for use with tape recorders given...
This circuit can control motors up to 40 V with a current up to 2 A and with appropriate...