This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from an approaching storm. The circuit was taken from a Popular Electronics from the 90s.
This temperature compensated circuit was found in a 1980s American documentation. The power supply...
This circuit is an improved version of the previous ones with the LM3914. We found it in the March...
This indicator was found in a 1974 publication, but it can be fitted with the BC548 transistor or...