Metal locator (CB7506E)

This simple metal detector was found in a 1960 Sylvania transistor manual. The phone must be high impedance or crystal.

AC Triac latch (CB7237E)
This circuit is suggested by a 1965 General Electric documentation. The triac must be in...
Precision Current Monitor (CB3995E)
This circuit is from the 1990 Motorola Linear Databook. The integrated circuit used is the LF355,...
High Speed Buffer (CB4991E)
This circuit from an 80's publication also features low input capacitance. FET can be a modern...