This circuit visually indicates that a high voltage is present in an outlet or other point. The neon lamp is common, and the appearance of the assembly is suggested in the same figure.
In the figure we have the way to use a common operational amplifier for AC signals. The resistor...
This configuration presents a negative resistance caracteristic such as the one found in...
The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x...