The circuit is from the 1994 National Semiconductor Linear Applications Handbook but can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
This circuit was suggested by Popular Elecronics from the 90's. The circuit has high input...
Figure 1 shows a circuit than can be used as time stage in timers, and other applications....
This circuit is from a Popular Electronics from 1993. The magazine is no longer printed, but the...