This circuit was found in a 1969 US documentation. It provides a signal that can be externally programmed as suggested circuits. The circuit can be used as a shield.
With this configuration it is possible to obtain an 80 dB gain from two 741 operational...
This is the common configuration for a 1 MHz crystal oscillator with a 7400. The circuit can...
This circuit with LDR and neon lamp has its operating frequency given by the light. The circuit is from...