This circuit, from the 70's, can be assembled with a more modern FET like the BF245. The circuit is powered by a 9 V battery, as its consumption is very low.
This circuit with signal acceptance filter was found in the June 1993 Electronics Now magazine. Other...
We found this 555 integrated-circuit tester in an old Electronics Hobbyst from 1977. The circuit is...
Found in a1969’s neon lamp documentation, this circuit uses a high voltage transistor. The output...