This circuit was found in the June 1991 issue of Radio Electronics magazine. The circuit uses two Hall effect sensors of the time. It can be assembled using modern equivalents.
This configuration from the 1970s can be applied to modern equivalent operational amplifiers. The...
This simple alarm using only transistors was found in a 1990 publication. It can be powered by D...
The circuit presented was found in the 1994 National Instruments Linear Applications Handbook and...