Issue with IRLZ44n

Other Hardware General Electronics
1

Hi, this is my first time using mosfets and want to use it as a switch to switch a 5v pump from a esp32 super mini c3. I've tried like every combination and the mosfet always gives 5ish volts or nothing except the one time I wired it High Side instead of low side in which it only would output the same voltage input into the gate. This is what my wiring is which I think matches what I found on google but still nothing.

Schematic_New-Project_2025-06-28(1)
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Here is the mosfet I ordered: https://www.aliexpress.us/item/3256806042313742.html?spm=a2g0o.order_list.order_list_main.23.b1c11802mqGQZK&gatewayAdapt=glo2usa

2

How much current (Amps) does the pump require?

3

Shouldn’t there be a 10K resistor between gate and GND ?

Something like this

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1 Like
4

When you measured "5ish" volts, where were your voltmeter probes connected?

5

Schematic_New-Project_2025-06-28(1)
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  • The pump will require a kickback diode.

  • Show us an all encompassing schematic.

  • Show us good images of your ‘actual’ wiring.

  • BTW, 3V3 on the gate might be too low.

1 Like
6

The pump motor will destroy the MOSFET with high voltage spikes, unless you use a kickback diode, as show below (D1).

Also, you should NEVER use the Arduino 5V output to power pumps, servos or solenoids, as that may damage the Arduino or even the host computer, if connected via USB.

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2 Likes
7

I will take a SWAG as it appears the part you have is not the part you think you have. Looking at your link and what info I could find the part will be marginal on a 3V3 system. Read the comments the first one when I looked stated you needed about 5V to get it to work. @jremington is the best solution. @LarryD will also work but you need to make the suggested changes. @UKHeliBob is a common way to connect them but I do not like it as the resistors become a voltage divider although it generally works.

A much better answer could be obtained if we knew the pump parameters and what the power supply is rated at. Connecting to the Arduino is a No-No.

8

Thanks for the replies, I fixed it with a 10k resistor between gate and GND, so thank you UKHeliBob, I seem to be able to power the pump fine now and the esp32 works fine, the pump is kinda weak and works from 5-12v at like 100ma and the esp32 is rated to handle up to 6v but in my experience (cranking up the bench power supply till it dies) can handle like 7v. Is the kickback diode necessary? I really don't want to wait for shipping again.

Here is my wiring that works rn:

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9
  • Yes
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10

If you continue without the kickback diode, you will soon be ordering a replacement MOSFET.

1 Like
11

Only if you want the transistor to be able to switch on a second time.

To be fair, the first kickback may not kill the transistor. It might survive several kickbacks. But it might not. And it will die. And that could happen the first time you switch it off.

12

Alright then, what diode should I use?

13

1N400x will do. The diode current flow does not exceed the pump current flow, so check the diode data sheets for the maximum allowed pulsed current.

Kickback diodes can be salvaged from any discarded toy with a motor.

14
  • Many here use 1N40XX
    example, 1N4007.
15

Thank you both, now give it 2 weeks to show up.

16
  • Do you have any diodes ?
17

Wait, I found one in the bottom of my random crap bin, does it just go in between the drain and the motor negative or did i read the drawing wrong?

18

The drawing in post #6 is correct. Observe the indicated diode polarity when installing.

19

Does this look right? I don't want to fry anything

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20

No. The diode arrow symbol points toward the white band on the diode casing.

The diode should actually be placed across the motor terminals, with the white band closest the positive motor power supply connection.

Keep in mind that breadboards are designed for low power logic circuits, not for motor or servo current levels. The tracks may burn.