This circuit, which can be used as a shield, was found in a 90s Electronic Design. The circuit uses a diac and the transistor can be general-purpose.
This filter, from an audio publication from 1977, passes the frequency range corresponding to the...
In the figure we have three voltage doubler configurations that can be used in high and low...
This circuit was found in Motorola documentation from 1966. The lamps are according to power and...