This circuit triggers a small water pump when the humidity detected by the sensor is reduced in a flower bed or potted plant. The circuit must use a source according to the driven water pump.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...