Running a small 3v pump

[tobz]

Hi all,

For a project I'm working on I need to turn a small pump on/off.
This is the pump I have https://sparks.gogo.co.nz/Miniature-Air-Pump---KPM14A-Model_-3v-p814.html

Its 3v 380ma (apparently only really draws about ~200ma) - this is way over the 6ma recommended for the Pycom pins right?

So what do I need to be able to run it safely?
(I'm a noob at this, the programming side is more my thing)

Thanks

[Eric73]

@tobz Hi, yep you need an hardware advise , what are the characteristic of the +5V power supply you use to power your pycom board? can it draw such current+power supply of pycom board?

[tobz]

@eric73 The plan is to run on battery 3.7v lipo + solar. The pump is only on for a few ms.

[robert-hh]

@tobz You'll need an external transistor for switching. A n-channel MosFet would do, like a 2N7002A or similar with 500 mA Drain/Source current capability.

Gate -> GPIO port
Source- -> GND
Drain -> Motor -
Vcc -> Motor +

You can also us a bipolar transistor, but then you need a resistor between GPIO port and base.

[Eric73]

@tobz I dont now if you prefer SMD or traditionnal component , so this value are for traditionnal.
PIN_CTRL is pycom pin you use for command, 3.7V is directly your battery source, D2 is only here to drop 0.6V so your pump only have 3.1V on is indcutance (i dont know what happen if you drive directly your pump on 3.7V there no real datasheet for your pump) D1 is free wheel diode to protect other component when you switch off the pump.

[Martinnn]

1N4148 is maybe a bit underpowered with 0.3 A rating. Better use 1N400x.
Do you mean BS170? BS170 has a RDSon of 6 ohms... gives 2.3 V drop at 0.38 A. Not funny.
You need something with lower RDSon (maybe < 0.1 Ohms) and low VGSth.
https://www.mouser.ch/Semiconductors/Discrete-Semiconductors/Transistors/MOSFET/_/N-ax1sfZ1yzvvqxZgjdhub?P=1yuk7vzZ1z0z63xZ1yzxnagZ1z0y3zr&Rl=ax1sfZgjdhp5Z1yw8qn6Z1yw8pmiSGTax1sfZgjdhp2Z1yw72sfZ1yw78hpSGT&Ns=Pricing|0
LiPo voltage range is 4.2 downto maybe 3 V, around 3.6 V nominal. So I'd maybe drop D2; if you really need 3.0 V (I doubt it) you'll have to add an LDO.

[nespressif]

Hello, I usually use this mosfet, I leave you the link and the assembly scheme.

IRF520

Scheme

[tobz]

Thanks everyone I'll figure out how to put your feedback into place :)