This circuit has a normally low output that is triggered by a high pulse. The circuit is from Radio Electronics from November 1984. The frequency is given by C1.
We found this circuit in a 1990 documentation. The operational amplifiers are type 741 and the LED is...
We found this circuit on an Elektor from the 90s. The frequency is given by capacitor C1. The...
Found in National Semiconductor publication from the 1980s. This gain-100 circuit can be...