We found this circuit in the September 1971 issue of Radio Electronics magazine. The sensor is an LDR and R1 adjusts the sensitivity. A relay with the appropriate voltage can be used instead of a buzzer.
We found this circuit in the Linear Applications Handbook by National Semiconductor. The circuit is...
This wide-range radiation monitor was found in a 1980s documentation. The circuit uses a diode as a...
This circuit is from an article that appeared in the June 1974 issue of Radio Electronics...