Hello
Can I use my Micro to turn on & off a 12v dc motor that draws 3 amps? I would connect 12 v to the servo power change the channel to an output. I am trying to use the micro as a timer on for 2 second off for 2 seconds and be adjustable. as a test I am doing it now with 6 v power to the servo power and a 6v relay (using the signal wire as the ground for the relay) switching 12v with the relay, would like to not use the relay and 2 different voltages. Or could I use a power mosfet in place of the relay if so could you help my with a circuit to switch the mosfet with the Micro using 12 v to power the Micro
We talked on the phone earlier today; I am sorry we did not respond to your question here. With the additional information in your post, I think I can offer some more advice than what I told you over the phone.
First, you could definitely use a MOSFET controlled by your Maestro to switch the motor on and off. You would basically connect the motor to 12 V through the source and drain, and use the Maestro’s output to control the gate of the MOSFET; you would not need to connect the 12 V directly to the Maestro. This page contains a diagram of a similar circuit.
However, I think a simpler solution might be to use our RC switch with medium low-side MOSFET. This switch expects a standard RC pulse signal, the same kind that is used to control servos, so you could connect it directly to one of the channels on the Maestro. Then you could simply connect your 12 V supply across the load supply and GND pins, and your motor across the MOSFET output and GND.
When you say your motor draws 3 amps, is that a when it’s stalled or free running? (If 3 A is not the stall current, do you know what the stall current is?) This could make a big difference as to whether a given MOSFET or the RC switch I mentioned are sufficient for powering it. Also, with these suggestions, I am assuming that you only care about running your motor in one direction at full speed; you would probably have to do something more complicated with a motor driver or controller if you want bidirectional or speed control.
The motor draws 1.5 amps at max load I have not tried stalling it but manufactuer recomends 5 amp fuse which is installed. You are correct the motors will be run @ full speed in one dirrection. I did build a mosfet circuit using the signal to trip the mosfet and switch the ground running power & ground directly from battery and powering the meastro separtly from the battery the motor takes a second or two to reach max rpm that does not happen when connected directly to battery any idea why this might happen? The RC switch you suggested that only has one mosfet so I would need one switch for each motor? Now the code question I am wanting to run the motor for about 2 seconds and turn off for about 1 second 2 different motors when 1 is off the other is on the code i came up with seems to have them on and off the same amount of time see below could you help with this?
Could you provide some details about the specific MOSFET and the circuit that you’re using? You are correct that the RC switches only have one MOSFET each, so yes, you would need one for each motor.
As for your code question, I am not sure I understand the timing pattern you are trying to get. You mentioned you want to “run the motor for about 2 seconds and turn off for about 1 second”, and also “when 1 is off the other is on”; does this mean the second motor will be off for 2 seconds and on for 1?
I am using a IRF510 power mosfet with a IN 4001 diode. I can not seam to copy my circuit to this page. I am running the power directly to the motor running the neg through the mosfet and taking the power back to ground through the diode.
I guess I need a capacitor in the circuit somewhere I will check out the link you added and find out something about capacitors and how to place them in a circuit if you think that is why the motors start slow.
I am also going to try one of your RC Switches does it need separate power from the load power and where do you connect the signal from the meastro?
I would llike to turn motor #1 on for 2 sec and turn it off for 1 sec then turn motor #2 on for 2 sec and off for 1 sec so the on time for the 2 motors would overlap is this possible?
Based on your description, I am not sure how you have your diode connected. If you have a picture of your circuit, you can attach it to your post by clicking on “Upload attachment” on the page where you write a post, under the text box.
Just to make sure, what kind of power supplies are you using to power the motor and the Maestro? (Is the Maestro plugged into USB or are you powering it through the VIN pin?) Also, have you made sure that the channel your MOSFET circuit is connected to is set to be a digital output instead of a servo output?
Since you already have this circuit and are close to having it working, I think we should continue trying to figure it out. I feel that trying to use an RC switch at this point would just complicate things.
Your code should look something like this to produce the motor timing that you described:
begin
8000 0 servo # motor 1 on
500 delay # wait 0.5 s
2000 1 servo # motor 2 off
1000 delay # wait 1 s
8000 1 servo # motor 2 on
500 delay # wait 0.5 s
2000 0 servo # motor 1 off
1000 delay # wait 1 s
repeat
