Suggested by Raytheon in 1967 documentation this circuit uses a lightbulb and LDR optical coupler of the time. The transistor determines the maximum current.
This notch filter was found in National Semiconductor documentation from the 1980s. Operational...
This circuit can shift the phase of a signal from 0 to 360º. FETs admit equivalents and the...
Suggested by Motorola documentation from the 1980s, this circuit makes use of MOSFETs of the time....