This circuit is from the National Semiconductor's Linear Applications Handbook of 1994. The circuit can be implemented with equivalent operational. The detected voltage is given by the diode.
This circuit is from an old manual of operational amplifiers. The setting can be adapted to work...
The operational amplifiers used on this Motorola circuit from the 1970s are no longer common, but...
This circuit uses a feedback system that latches the relay when closed. The circuit uses an...