arduino mosfets and bipolars

Hi

I am trying to build circuit for arduino uno and small lego motor. Using 9v battery.

I have seen some examples of arduino circuits that don't use relays with motors they use bipolar transistors.

The one mentioned is a Tip120. When I search on my suppliers site I get two options:
https://cpc.farnell.com/jsp/search/...se&skipParametricAttributeId=&prevNValues=411

sorry for rubbish big link!

A 65mW and a 65W. Which should I choose?

I received more advice about using Logic level Mosfet. Can this be used the same way? With no relay just a diode?

Also when I search for logic level mosfets I searched for Vgs between 3.75 and 5v. Is this correct?

cpc website uk . shortened link
**broken link removed**

Which ones can I select to fit my small lego motor and 9v battery circuit?


Can anyone help me out?
Many thanks

First get ready to experiments. There are many suitable BJTs and MOSFETs but some are best with more than 9VDC.
Measure the logic output voltage from your Arduino to a 3K load resistor, and build a logic voltage source from a 9V battery, with a SPDT switch. Test a logic MOSFET from your logic source, with the motor and 9V battery before you connect it to Arduino. Be sure to connect a protection diode across the MOSFET as the motor is an inductive load.
Make sure there is a large capacitor across the 9V battery (like 1000 uF) to protect Arduino from voltage kicks the motor can generate.
BJTs have much larger resistance when open, a heat sink is needed. I would use one for the MOSFET, too. When the motor stalls, the current peaks high. Maybe your 9V battery will not live long to feed the motor.