This circuit is from a 70s documentation. The maximum sampling rate is 800 Hz. The operational amplifier is a common type at the time.
Found in a 90's EDN, this circuit generates signals in the frequency range given by the graph. The...
The figure shows a circuit that shows how to control an optodiac to trigger a triac from the...
This circuit, from an American documentation from 1975, can be assembled with modern transistors such as...