12V DC Water Pump to be controlled by Arduino?

So I’m a super newb when it comes to the electronics in general. I’m working on a project though, and I’ve managed to make everything work so far. I just got stuck now that I have to connect my DC pump to my arduino, and control it with the arduino. I’ve been searching the internet, and I’ve seen that everyone seems to be using some sort of relay, which I dont have for the time being. I was wondering if there was a super simple way of connecting the pump to my arduino and controlling it with digitalWrite? I do have a BC547 transistor if it could help, but as I said, I actually have no idea of what I’m doing lol.

Any help is appreciated <3

thanks in advanced

Bc547 might be suitable, depending on the model of pump. If it is very low current, say less than 600mA, then bc547 might be ok. You will need a resistor in series with the base, such as 330R. You will also need a diode to protect the circuit from damage caused by the reverse voltage generated when the pump is switched off, such as 1n4001 or similar.

But only tiny pumps would draw less than 600mA. If the pump needs more current, get a MOSFET with a logic-level gate such as IRL520 or STP16NF06L. You will still need the diode, but the resistor won't strictly be needed.

The pump requires 5W, so that would be around 0,55 Amps, as I have a 9V powersupply. I know it's a 12V pump, but isn't it fine with only 9V, as I don't need the full power of it?

Maybe. But at 9V it may draw more than 0.55A. You will have to measure it.

You may wise to use 2 or 3 bc547 in parallel to boost the current capacity, as the current at startup can be much higher than the normal running current. Each will need is own base resistor. 330R should be ok for 2, but for 3 go with 470R.

Ok, thanks a lot!!

A DC pump has a DC motor. Any DC motor that runs at 0.55A normally will pull many amps at switch-on
which will destroy a BC547.

A logic level MOSFET is appropropriate here, 0.05 ohms or less will handle many amps of pulse load.

Note that the power supply will have to either handle the max current spike, or current limit during the
spike. If its the sort of supply that cuts out on overload it will need to be rated for larger current than
the motor's startup spike (aka stall current).

Whether a 12V pump works at 9V is hard to be sure, but its pretty plausible.

All DC motor/inductor/relay switching circuits require a free-wheel diode, if this is omitted then you'll
damage your circuit.

I was wondering. I've got 5 h-bridges in my project controlling 5 seperate motors. Would I be able to control the DC pump with a h-bridge aswell? Those h-bridges are build with 2 BC547, 2 TIP-120 and 2 TIP125 transistors.

Yes. When the H-bridge is set for the forward direction. If the H-bridge is set for the reverse direction, that does not mean the pump will pump backwards. It will probably still pump forwards, but less efficiently.

Those Tip120 and Tip125 are very old designs and may get hot while the pumps pump less efficiently. Modern MOSFETs are more efficient and stay cool.

Ok, I saw that it was mentioned that DC motors will kill bc547. I just wanna make sure the DC pump dont kill my bc547 transistors if I test the pump with my h-bridges?

I would guess no. The tip-120 and tip-125 handle the high current. The bc547 are safe. But without a schematic, that is a guess.

If you have a few spare TIP120s around, better use those to switch the pump. No need for the high side switch (the TIP125 PNP Darlington), that's just unnecessary loss.

And do get yourself some modern-day parts. Logic level MOSFETs for switching your pumps, and H-bridges like the DRV8835 or TB6612FNG. They'll work much better, and produce little to no heat.