Which transistor should I use for this circuit?

[rahulsathya]

Transistor - 2N222A
Motor ratings - 4.5v, 0.5A

Aim- Find the suitable transistor for this circuit
Problem - The motor is not getting enough current through the transistor when the base is high [Motor is running slow]. I think the transistor am using is not suitable for this motor. I would like to get suggestions for the transistor. Also, I have tried placing a resistor between base and ground.

[ruilviana]

Hi,
The transistor is connected wrong.
The collector must be connected to + 5V.
And I suggest a resistor between the port and the base of the transistor

RV mineirin

[rahulsathya]

I think accidentally chose PNP Transistor while drawing in a software. The transistor am using is an NPN Transistor.
Secondly, I have tried connecting a resistor between pin 8 and base. The motor was barely running when I added resistor.

[jremington]

This is a typical motor driver circuit. The diode is required, to prevent high voltages from the motor windings burning out the transistor.

You need to choose a transistor that can easily handle the motor current.

[ruilviana]

The best solution for controlling motors is Mosfet

[ruilviana]

[rahulsathya]

I'll try this and let you know

[SteveMann]

I wouldn't use a transistor. A logic-level MOSFET is a better switch. In this image just replace the relay with your motor.

[rahulsathya]

Will IRF960 mosfet be suitable for driving my motor (4.5v/0.5A) ? I'll try it if you think it will be as I have not worked in mosfets.

[LarryD]

You need a logic level MOSFET transistor.

[rahulsathya]

Should I use IRF610 or IRF960 for my motor (4.5v/0.5A)

[rahulsathya]

Which logic level Transistor do you suggest for my motor (4.5v/0.5a)

[rahulsathya]

After connecting the 10k resistor between port and base, the motor didn't run

[LarryD]

See this PDF

Logic level MOSFETS

[SteveMann]

Probably, I just posted an example schematic. I use whatever is in my junk box. Usually an IRFZ44N.

[LarryD]

10k is too large, try 220 Ω

But, the transistor may/will get hot.

Use one of the MOSFETs IN THE PDF I linked you to above.

[rahulsathya]

Thanks a lot. I'll surely check them out

[MarkT]

@jremington

You need to choose a transistor that can easily handle the motor current.

Change that 10k resistor to 180 ohms or so and you might have something plausible. As a switch BJTs need lots of base current (typically 5% to 10% of the load current) to saturate properly (so they don't overheat). Thus this circuit might be good to 600mA load or so, above that the optimal base current starts to be more than an Arduino pin can handle.