The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply voltage (two batteries or source) can be from 9 to 12 V.
We found this interesting configuration in a 1976 technical documentation. Equivalent diodes can...
This circuit can generate signals of different frequencies, switched by a DC voltage. The...
This circuit, from a publication from the 1970s, can be implemented with more modern transistors and 6 or...