In this circuit of an American documentation of the 90s, when the light is cut, we have the production of a pulsating tone. R3 determines the trigger sensitivity.
This Sample & Hold circuit configuration is from an American 1980s documentation. The circuit uses...
By LED flashes you can get an idea of the degree of moisture in the soil. The sensors are wires...
Found in an old Popular Electronics, the purpose of this circuit is to give a strong discharge in an...