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can you give me advise which transitor is best for switching 5V usb voltage in o...

pmamatis

@copilot can you give me advise which transitor is best for switching 5V usb voltage in order to drive waterpumps with 300mA

copilot

For switching a 5V USB voltage to drive a waterpump with a current requirement of 300mA, I recommend using a N-channel MOSFET due to its high efficiency, lower voltage drop, and simplicity for such an application. A good choice would be to select a logic-level MOSFET, as it will be fully turned on (saturated) at the lower gate voltages provided by microcontroller GPIO pins, such as those on the ESP32.

Here are two commonly recommended logic-level N-channel MOSFETs for your requirements:

IRLZ34N
- Threshold Voltage (Vgs(th)): Typically around 1V to 2V, ensuring it fully turns on at the 3.3V logic level available from the ESP32.
- Continuous Drain Current (Id): Greater than 300mA, specifically around 30A, which is way more than what's required for your application but provides a good safety margin.
- Rds(on): Very low on-resistance, ensuring minimal power loss across the MOSFET when on.
2N7000
- Threshold Voltage (Vgs(th)): Approximately 2.1V, making it suitable for logic-level operation as well.
- Continuous Drain Current (Id): Up to 200mA, which is slightly lower than your requirement. For a safety margin, it's often recommended to use components rated for higher than the actual anticipated current. Therefore, consider this option if your water pump can operate slightly below 300mA or if you can find a variant or similar MOSFET with a higher current rating.
- Rds(on): Slightly higher on-resistance compared to power MOSFETs but still acceptable for low current devices.

Given that the 2N7000 is on the edge of your current requirements, I'd lean towards recommending the IRLZ34N for its higher current capacity, low Rds(on), and overall headroom for your application. This will ensure reliable operation and reduce the chances of overheating and failure.

When interfacing this MOSFET with your ESP32, ensure you include a pull-down resistor (10kΩ is a common choice) between the gate of the MOSFET and ground to prevent the MOSFET from turning on unexpectedly when the ESP32 pin is in a high-impedance state (i.e., during reset or not actively driven).

Connecting the MOSFET:

Gate: Connect to ESP32, for example, U1:D5 (assuming D5 will be the control pin)
Drain: Connect to one of the waterpump terminals.
Source: Connect to GND.
Pump's other terminal: Connect to the positive side of your 5V power supply.

And, of course, do not forget to connect the ground of the 5V power supply to the ESP32's ground to ensure a common reference point for all components in your circuit.

pmamatis

can insert the Mosefets 2N7000 and already connect them to GPIOs of the ESP32?

copilot

Certainly! I'll guide you through inserting two MOSFETs of type 2N7000 into your project and connecting them to GPIOs of the ESP32 for control. Based on the list of available pins, I'll use D5 and D18 GPIOs for these connections. Let's assume each MOSFET will drive a separate water pump, requiring a control signal.

Project Update with 2N7000 MOSFETs

Components to Add:

Q1: 2N7000 MOSFET for water pump 1
Q2: 2N7000 MOSFET for water pump 2

Connections:

Connecting Q1 (MOSFET for water pump 1):
- Connect U1:D5 (GPIO for control) to Q1:Gate.
- Connect Q1:Drain to one terminal of water pump 1.
- Connect Q1:Source to U1:GND (common ground).
- The other terminal of water pump 1 should be connected to the positive side of the 5V power supply.
Connecting Q2 (MOSFET for water pump 2):
- Connect U1:D18 (another GPIO for control) to Q2:Gate.
- Connect Q2:Drain to one terminal of water pump 2.
- Connect Q2:Source to U1:GND (common ground).
- The other terminal of water pump 2 should be connected to the positive side of the 5V power supply.

Additional Components:

Make sure to add a pull-down resistor between the gate and source pins of each MOSFET to ensure they remain off unless explicitly driven by the ESP32:

R1: 10kΩ, connect between Q1:Gate and Q1:Source.
R2: 10kΩ, connect between Q2:Gate and Q2:Source.

This configuration ensures that the MOSFETs are in their OFF state when the ESP32 GPIOs are not actively driving them, preventing unintended water pump activation due to floating gate voltages.

Summary of New Connections:

Connect U1:D5 to Q1:Gate.
Connect Q1:Source to U1:GND, and Q1:Drain to Water Pump 1 (+ terminal).
Connect R1:1 to Q1:Gate and R1:2 to Q1:Source.
Connect U1:D18 to Q2:Gate.
Connect Q2:Source to U1:GND, and Q2:Drain to Water Pump 2 (+ terminal).
Connect R2:1 to Q2:Gate and R2:2 to Q2:Source.

Remember: The negative terminal of each water pump should be connected to the 5V power supply's ground, which must be shared with the ESP32's ground to complete the circuit.

Resistance

10kΩ

J1 P2 - U1 GND

Resistance

10kΩ

Resistance

10kΩ

J1 P2 - U1 GND

Resistance

10kΩ

Resistance

10kΩ

J1 P2 - U1 GND

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ESP32 waterpump interface

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pmamatis / ESP32 waterpump interface

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