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Topic: My Nano's pin 9 is outputting 1 mA only!!! (Read 123 times) previous topic - next topic


Jan 12, 2019, 03:45 pm Last Edit: Jan 12, 2019, 03:48 pm by sidsr003
I'm using an Arduino Nano to control the base of a 2N2222 to drive a 200 mA motor.
The power supply at the collecter is 3V 1A max so it is sufficient.

When I connect the 5v pin to the base, it runs amazingly, however, when I connect to
pin 9 on HIGH, it barely moves. I used a multimeter to check the current and I see that
the 5V pin allows about 8 mA to the base, while pin 9 on HIGH allows only 1 mA.
Why is this? How can I use pin 9 for around 10mA?

Btw, even the other pins output less current. Only 5v outputs sufficient current.


Did you set pin 9 to OUTPUT mode?
Code: [Select]
pinMode(9, OUTPUT);


Can you provide a schematic for us ?

What value of resistor have you got in series with the connection to the transistor base ?


I have set the pin as OUTPUT and there is no resistor to the base. That's what surprises me.


Sorry, this is a quick MS paint schematic.


You need a resistor between Arduino pin and base of the transistor. You need a reverse diode over the motor.

You might have blown the pin of the Arduino; if above does not help, use another pin to test.
If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.


You might have blown the pin of the Arduino; if above does not help, use another pin to test.
...after adding the current limiting resistor and snubber diode!
Experienced responders have a nose for laziness, (they were beginners once)... Sure, there are trolls, chest-beaters, and pretenders - but the help you'll get here is about as good as it gets - if you try to help youself!.

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