This circuit was found in the May 1984 issue of Radio Electronics magazine. It analyzes the exhaust gases emitted by a car. The circuit uses a special gas sensor from that time.
This circuit uses an operational amplifier to simulate an inductor. The circuit is from old...
This voltage level-triggered circuit was found in a 1969 Ferranti English documentation. Modern...
Found in a 90s General Electric documentation, this circuit has a drain current of just 1.5 uA....