Circuit Documentation

Summary

This circuit appears to be designed to control a water pump based on the moisture level detected by a soil moisture sensor. The SparkFun Soil Moisture Sensor is used to measure the moisture level of the soil, and when the moisture level falls below a certain threshold, the sensor's signal triggers an NPN transistor to switch on a water pump. A resistor is used to limit the current to the transistor's base, and a diode is placed in parallel with the water pump to protect against voltage spikes (back EMF) when the pump is turned off. The entire circuit is powered by a 5V battery.

Component List

NPN Transistor (CBE)

• Description: A bipolar junction transistor used as a switch or amplifier.
• Pins: Collector, Base, Emitter

Resistor

• Description: A passive two-terminal electrical component that implements electrical resistance as a circuit element.
• Properties: 200 Ohms resistance

Diode

• Description: A semiconductor device that allows current to flow in one direction only.
• Pins: Cathode, Anode

SparkFun Soil Moisture Sensor

• Description: A sensor that measures the volumetric content of water in soil and gives a moisture level as output.
• Pins: VCC, GND, SIG

5V Battery

• Description: A power source for the circuit.
• Pins: Positive (+), Negative (-)

Water Pump

• Description: An electromechanical device designed to move water through the system.
• Pins: Positive, Negative

Wiring Details

SparkFun Soil Moisture Sensor

• VCC: Connected to the anode of the Diode and the positive terminal of the 5V Battery.
• GND: Connected to the emitter of the NPN Transistor and the negative terminal of the 5V Battery.
• SIG: Connected to one end of the Resistor (pin1).

Resistor

• Pin1: Connected to the SIG pin of the SparkFun Soil Moisture Sensor.
• Pin2: Connected to the base of the NPN Transistor.

NPN Transistor (CBE)

• Base: Connected to pin2 of the Resistor.
• Collector: Connected to the negative pin of the water pump.
• Emitter: Connected to the GND pin of the SparkFun Soil Moisture Sensor and the negative terminal of the 5V Battery.

Diode

• Cathode: Connected to the positive pin of the water pump.
• Anode: Connected to the VCC pin of the SparkFun Soil Moisture Sensor and the positive terminal of the 5V Battery.

5V Battery

• Positive (+): Connected to the VCC pin of the SparkFun Soil Moisture Sensor and the anode of the Diode.
• Negative (-): Connected to the GND pin of the SparkFun Soil Moisture Sensor and the emitter of the NPN Transistor.

Water Pump

• Positive: Connected to the cathode of the Diode.
• Negative: Connected to the collector of the NPN Transistor.

Documented Code

There is no microcontroller code provided for this circuit. If the circuit is intended to be controlled by a microcontroller, the code would be necessary to read the sensor data and control the transistor gate to activate the water pump. Since no code is provided, it is assumed that the sensor directly controls the transistor without the need for a microcontroller.