Need help with a Mosfet

[LazyDev]

Basically, if I set pin 9 low on the Arduino, the mosfet drops to 9 V, high is 12 volts.

 

The low is supposed to be 0 Volts as this controls power to a motor.

 

This is my very first schematic design and first use with a mosfet.

 

 

[Guest]

Whats D2 for?

[LazyDev]

When the motor powers off, prevent reverse current. Probably have it in the wrong place.

[Guest]

When the motor powers off, prevent reverse current. Probably have it in the wrong place.

You should turn around that diode.

Use quote when responding so I can see your response.

[LazyDev]

You should turn around that diode.

Use quote when responding so I can see your response.

I had the diode set the wrong way on the schematic.

[Guest]

I had the diode set the wrong way on the schematic.

So on pcb its in good way?

Did you tried to disconnect D1?

[LazyDev]

So on pcb its in good way?

Did you tried to disconnect D1?

I DC'd the diode and the power to the motor stopped completely.

[Guest]

I DC'd the diode and the power to the motor stopped completely.

There is no power even if pin9 is high?

[LazyDev]

I think I figured it out. In diode mode, my multimeter shows 0.5 on S > D, and 1.8 on D > S with the mosfet off.

 

I'll try DC'ing the gate.

[LazyDev]

There is no power even if pin9 is high?

I've separated the gate pin of the mosfet and power is still going through the d > s. Do I have a dead mosfet?

[Guest]

I've separated the gate pin of the mosfet and power is still going through the d > s. Do I have a dead mosfet?

In that case probably.

But I would check pcb again to be sure everything is connected as it should.

[LazyDev]

In that case probably.

But I would check pcb again to be sure everything is connected as it should.

Triple chacked everything, nothing is shorting. Could a PWM signal into the gate kill a mosfet?

[Charger]

Triple chacked everything, nothing is shorting. Could a PWM signal into the gate kill a mosfet?

pwm is is fine

[Guest]

Triple chacked everything, nothing is shorting. Could a PWM signal into the gate kill a mosfet?

It should work with pwm. Try to add 10k resistor between G and S

[Charger]

why are you not using something like a tip120 also do you have any images of what you are working one?

if you look for arduino tip120 you will be shown how to set that up as a motor control

its been some time since i have done anything with an arduino

[LazyDev]

Replaced the mosfet and the motor now turns on/off when requested. I've added a 16K between the gate and source, 16K is the closest I had to 10K. I did have an 8K but it's better to go over than under

 

Thsnks for the info with the Tip 120. Mosfet for a motor drawing 500 Ma probably is overkill but this circuit is designed to use a total of 1 A as it is running on a robot.

 

I don't have another spare diode, but D2 (in the pic above) should provide some protection against reverse current spikes?

[LazyDev]

PCB sitting on the part it powers.

 

I also changed D2 to a 1N5819 as the previous diode was defective.

[Guest]

Replaced the mosfet and the motor now turns on/off when requested. I've added a 16K between the gate and source, 16K is the closest I had to 10K. I did have an 8K but it's better to go over than under

 

Thsnks for the info with the Tip 120. Mosfet for a motor drawing 500 Ma probably is overkill but this circuit is designed to use a total of 1 A as it is running on a robot.

 

I don't have another spare diode, but D2 (in the pic above) should provide some protection against reverse current spikes?

D2 should be parallel with motor as D3 on this schematics

[LazyDev]

What software could I use to design a PCB within a selected size? Would prefer freeware, but would consider a paid version.