This circuit also appears elsewhere on this site, obtained from other sources. This is an 80's American schematic book. Instead the lamp can be used white high-brightness LEDs.
Any JFET can be used in this circuit suggested by Electronics Now magazine, April 1993. The...
This circuit allows you to view two low frequency signals on a single channel oscilloscope. It was...
Found in an old Popular Electronics this circuit is still current. The SCR can be of the 106...