This variable oscillator with power step for alarms was found in an American documentation from the 90's. The power transistor must be equipped with a heat sink.
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...