Hi guys Ihave just started with electronics. Im struggling with using a mosfet to operate a low voltage RC-servo with the arduino. It was suggested that I use a IRF630 or IRL540. I have being reading and if you don't apply the max voltage at the gate then the current draw will be limited. My servo maxes out at about 400ma. 5v Would either of these be a good choice
Another question I was looking first at using a TIP122 NPN but I think now I understand that a NPN would switch the neg. side not really good for arduino.
Thanks
Rick

 

The arduino will directly feed the data pin on a servo but it sounds like you are trying to switch the power to the servo. This isn't normally necessary but you could do it with a PNP transistor such as 2N2907 which would easily handle the 400mA while being driven by the arduino.

 

Thanks
I think that the servo will always be on (trying to stay in last position) so i wanted to turn it off as it would not always be used. I have the above mentioned mosfets but you think the 2N2907 would be better

 

If servo at final position, and there is no torque on its shaft, then current stops
except for internal control circuit.

https://www.jameco.com/jameco/workshop/howitworks/how-servo-motors-work.html


Regards, Dana.

 

Ok Im just using the servo to lift the flapper in the toilet I read the article at the link you sent danadak. I want the servo to move 180 degrees. I see that the rest position is at 0 then it will rotate 90 degrees in both ways. So my servo will never be in the rest position. Im not sure if this makes a difference
Rick

 

Take a look at his article.

Yes, you servo is at a resting position when its position, as deemed by the controller
insider servo, is at correct position. Note comments on decreasing torque with small
position errors.

Regards, Dana.