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 circuit from the 40's is a conventional analog multimeter with several scales. Its accuracy will...
With this circuit, an external circuit can be controlled by turning it on or off and reversing it (if...
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...