This circuit was found in a 1968 US publication. Transistors used are uncommon today. The circuit can be adapted to operate with modern equivalent components.
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...