This sensor circuit for currents of the order of nanoamperes was found in an American documentation from the 1980s. The components are from that time.
This lock-up alarm circuit was found in a 1990s Radio Electronics magazine. The sensors are...
This bass and treble control only attenuates the corresponding signals, requiring further...
I found this circuit in an article in a 2003 publication. The circuit is an example of how to...