transistor usage

Hello World!

First of all, I am a newbee in electronics...

I would like to manage a water pump (max 6V, 30mA) with an arduino uno. The pump works well if I connect it on the 5V pin and the ground. To manage it, I have a NPN S9013 transistor. My schema is : - arduino 5V connected to the collector - arduino pin 8 connected to the base through a 1kOhm resistor - the emitter connected to - of the pump - the + of the pump connected to the GND pin of the arduino

The arduino is power by the USB port.

The arduino code is as simple as:

void setup(){ pinMode(8,OUTPUT); digitalWrite(8,LOW); }

void loop(){ digitalWrite(8,HIGH); delay(2000); digitalWrite(8,LOW); delay(2000); }

It doesn't work and I don't understand why. Can anyone help me?

The transistor is in the wrong place. It should be pump + to 6V, pump - to collector, emitter to ground. The 1K base resistor is fine. I find it hard to believe that the pump only draws 30mA. Do you have a datasheet or a photo of the pump nameplate?

groundfungus:
The transistor is in the wrong place. It should be pump + to 6V, pump - to collector, emitter to ground. The 1K base resistor is fine.

Or to put it pictorially, see attached. (My pic shows pin 7, but whatever…)

motor and transistor.png

First of all, thank you for your answers!!!!!!

It is a really cheap one: http://www.ebay.com/itm/Peristaltic-dosing-Head-6V-DC-Dosing-pump-For-Aquarium-Lab-Analytical-water-DIY/111343325641?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=23490&meid=60d22153fcd24cd197779d1f7bc2a00f&pid=100005&prg=10073&rk=3&rkt=6&sd=201087635665&rt=nc

I tried your solution without any success. I do not understand why did you put this diode.

I also tried another thing, with a 9V battery.

9V battery + connected to the arduino 5V and to the + of the pump Pump - connected to the collector emitter connected to the arduino GND and to the battery -

The pump works but it does not stop each 2 seconds... it should be because of the missing diode or is my transistor broken?

Hi, try +5V to pump +, collector to pump -, emitter to gnd, leave base connecton open, if motor runs then transistor is u/s. The diode is to prevent damage to the transistor and the arduino from current and voltage spikes fro the DC motor.

Tom..... :)

Do not put 9V on the arduino 5V pin.......

And the diode goes "backwards", cathode to +ve supply

Ok my transistor is OK.

Thank you for your explanation about the diode.

I will not try the 5V supplied with 9V any more, promise… (I have to leave my computer a bit…)

I think that it should be a loss of power because my pump, in rare situation moves a little bit (<1sec)

Thank you guys!

You help me well on my project.

I tried with another type of water pump which is asking 9V. Powering either the arduino and the pump with my battery, my pump works as wanted

Thank you!!!!