This detector uses an unusual sensor today. The circuit is from an 80s documentation. Its sensitivity is 10 ppm. The transformer has two secondary voltages.
With the configuration shown in the figure, a single pulse for a counter can be obtained from a...
This is one of the possible timer configurations with the 555. We found it in October 1986 Radio...
Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can...