Neon lamp heads or tails (T438E)

This simple circuit was found in a popular Electronics from August 1957. The circuit has few components and can still be assembled with ease today.

Current sensor shield (CB5250E)
Found in a 2005 Linear Technology application manual, this circuit provides 12-bit resolution output...
Power grid Interference Filter (CB6737E)
Found in a 1968 US publication, this circuit can operate on any power grid. The thickness of the wire...
Optical Shield for Medical Application (CB1556E)
The circuit shown in the figure is intended for medical applications where the sector in contact...