This 1968 circuit makes use of MOSFETs of the time. The circuit can be mounted based on modern common FETs. Observe the high supply voltage.
This circuit was found in an 80's documentation using an NE5514, operating at the time. The font...
This circuit generates sinusoidal signals between 300 and 3000 Hz. We find a 303 Circuits from the 90's....
This circuit from a 2003 documentation, has a protection system that disarms the power supply if...