This circuit was found in the 1991 Electronics Experimenters handbook. It can be used to display RGB signals on old NTSC televisions.
We found this circuit in an American documentation from 1964, but it can be easily assembled...
This useful circuit is used to test the insulation of cables, appliances, leaks in high voltage...
Carefully removing (and a lot of work) the cover of a metallic 2N3055 to expose its joints it...