This constant current charger from 1997 Linear Technology Applications uses common components at the time. The transformer is the critical component, being designed according to the load voltage.
This circuit was suggested by General Electric in a 1965 documentation. The circuit can be...
This circuit of an Electronics Now from the 90's produces an intelligent direction signal that has...
This simple amplifier stage with a transistor has a linear response from 25 Hz to 120 kHz. The...