ELF Monitor (CB21055E)

This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the 90s.

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Low Consumption Clinical Thermometer (CB14000E)
We found this circuit in the 1982 Selezione Radio magazine in Italy. The circuit uses an...
3 W Amplifier (CB6201E)
This circuit was obtained from Dutch documentation from 1967. It uses transistors of the time...
Triac photoelectric control (CB8274E)
This circuit was found in a 1966 General Electric book. The triac and the day are from that time...