This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from the 1994 Linear Applications Handbook by National Semiconductor.
This sophisticated circuit with two LF411 operational amplifiers appeared in the November 1984...
This circuit uses battery power, but it can be powered by an 80 to 200 V power supply, with no...
This interesting circuit, which can be used as an alarm, was found in a 1997 documentation. It...