A word of caution: switching 10amp is no small matter. You want to look into 2n3055's datasheet to make sure that it is up to it.I would also look into what value-add, if any, that little capacitor is doing. It is forming an lc tank with your motor and can cause ringing.
However a MOSFET might be a more sensible choice
I need to control the speed of a dc motor (0.5 A no load, to 10 A full load). In the picture you can see that I'm using a 2n2222 that controls a TIP3055 (or a 2N3055). The circuit works but I'm not sure that is perfectly ok... Can you check it out?I don't know if I need the two green resistors (with question marks), I didn't use them in the test but I saw that some people use them. What should be the values?Also: what is the functionality of the 1N4007 diode next to the motor? And do I need to put another diode from the collector to the emitter of the 3055?Thanks!!!
VCEsat is also 3V @10A, so there will be 30W of heat to dissipate. Well within the capability of a 2N3055, but it will require a fairly big heatsink nonetheless.May I suggest an IRL540 MOSFET? It could be used by itself and would not even need a heatsink with a gate drive of 5V and a drain current of 10A. It can handle sustained currents of up to 28A and peak/pulse current over 100A, so it should be able to cope with stall and start conditions fairly well.
IRL540 is not a good mosfet to use for switching 10A, its Rds(on) is 0.077 ohms max so it will dissipate around 7.7W when carrying 10A. Look for a mosfet with much lower Rds(on), such as IRLU8726PBF (0.008 ohms max).