Hi,
I have been using a logic level MOSFET for driving solenoids which was working great (with the help from this forum members)
I have a bunch of tip120 darlington transistor and I was wandering if I can drive solenoids/dc motors with that part?
is there any schematic someone can please share?
why to choose one over the other? (TIP120 over MOSFET)
Thanks
You should be able to use your TIP120 easily with a 5v Arduino.
Circuit B1 should suffice.
Darlington transistors consume more voltage (1-2V) than MOSFETs (mV). That voltage is lost for the load and costs battery energy.
what do you mean by consume? where does this consuming happening? is it because there is less resistance between collector to emitter?
BJTs are subject to one diode voltage drop; a Darlington is two BJTs so you get that drop twice.
From the table one can see:
3A means 3x2=6W heat
5A means 5x4=20W heat, and heatsink, and fan?
So darlingtons still can be used for moderate currents, but for new projects I'd only use logic level MOSFETs.
Thanks for that info!
If I would like to control the speed of the motor and the direction of a dc motor - how can I do that? what type of circuit I will need?
The motor controller typically has a direction pin and a PWM pin for power (speed...) control for each motor.
The consume means heat is generated in the diode junctions inside the transistor. That is why your TIP120 will get warm/hot when you use it. Are you going to mount them on heat sinks?
You will need a H-Bridge drive to do all that.
Preferably a MOSFET type to keep your heat low and efficiencies high.
Tom.. 
is there a schematic you mind sharing? or direct me to a circuit I can look at?
Hi,
Google;
arduino H bridge circuits
Just don't use the 298 H-Bridge, it is a dinosaur and very inefficient.
Tom....
This is a circuit I have found: link
a 2N3904 and 2N3906 will be valid for it?
This circuit have only 2 control pin from arduino - I have seen other H bridge with 4 control inputs. What is the differences?
The circuit is crap 
Your motor will not get more voltage than the controller Vcc - 1.4V, regardless of the external supply voltage.
Do you want to invent your own H-bridge circuit or buy one?
I would prefer to make one on stripboard from a working schematics.
Otherwise - buying a board is also an option.
Most H-bridges use integrated chips so that available circuit diagrams of those chips are not well suited for building a discrete clone.
But if you want to learn more then you can study the data sheets of such chips. Other topics are low-side and high-side switches from which you can form a discrete H-bridge.
Is there any specific H-bridge board you recommending?
Is this board is a good choice for driving 12V DC motor?
Fortunately that board from stone age is currently unavailable and hopefully will not become available any more.
Don't wonder if you don't get any more answers if you did not read carefully preceding answers.
Could you please explain to me why this is the case with this circuit? Where should the motor get the controller VCC -1.4V, if only the base of the transistors is connected to the controller.
