This control for 1200 W of power was found in the documentation of General Electric of 1966 has a activation delay. The triac must be according to the load.
This circuit generates sinusoidal signals between 300 and 3000 Hz. We find a 303 Circuits from the 90's....
This amplifier for audio transmission lines was found in a 1961 American publication. The critical...
Old phones with dials can be used in a simple home intercom system, as this circuit from Popular...