Circuit Project Electronic

Yesterday I tours an orchard of a friend. He consults about Moisture Meter Circuit. By this circuit uses for level moistness temple of the earth. Fine the value R2 give Meter read the value has 1mA. When the moistness in the earth is in the level that wants thus Meter will read level moistness lowland value have more. For Sensor Probe use copper wire or a nail is clean all right. The transistor use 2N2222 numbers or 2N2907 or BC549 or C1815 all right. The detail is other see in the circuit.