This circuit was found in a 1968 RCA documentation. The circuit can be designed with operational equivalents. Input signals can be up to 6 V in amplitude and the limitation is 78 dB.
This freezer alarm was found in a 1980s American documentation. The circuit uses a reed switch and...
This circuit was found in a Popular Electronics documentation from the 90s. It is possible to switch...
This circuit was found in an old Radio Electronics, but can still be assembled as the components are...