Found in a Popular Electronics from the 90s, this circuit presents the difficulty of obtaining the Geiger Tube. The other components are common, admitting equivalents.
Using a 741 op-amp this circuit high-pass to 10 kHz was found in the February 1995 issue of...
This circuit produces an intermittent ring tone being triggered directly by the telephone line. However,...
This two-port configuration of the 4001 was found in the April 1988 issue of Radio Electronics magazine....