So I have the mostfet swiching away with this gate/drain/source all connected and happy.
Now I'm curious how it will workin the real application.
If my arduino is circuit is driven by a seperate power supply or a battery.
How can I use a mosfet to control another power source. When there does not appear to be a common ground.
i.e. I can intrerupt the higher voltage ground easy enough. But then there doesn't appear to be anyway that the gate can complete it's circuit to turn on and off.
Am I over thinking this? or....
Should I be looking for some type of isolator device between the two circuits?
An optical isolator would allow one to not have to connect the ground connections between the Arduino and the external power source being switched by the MOSFET. Otherwise it is required that the grounds be connected.
I was thinking that I could use the optoisolater..
Soooo... with that said.
The ones that I have been looking at have 8 legs... 2 of the six aren't connected.
So we have 3 legs on one side and 3 legs on the other.
On the left side, you would have the low level logc vcc and gnd. Then there is the signal pin.
On the right side you have high level vcc and ground and the output pin.
Now my question is.
How will the mosfet handle the voltage.
I'm assuming that when I trigged on the low side. The high side voltage triggers. Which means that I would have a 90v feed coming out and into the gate.
If I understand the mosfets correct. Most of them have a 20volt over ground signal.
Am I looking for certain kind of mosfet to handle the 90v. Or do have to do something else.
Without knowing what specific isolator, MOSFET, load device and external circuitry wiring and power, it's hard to comment on it. If you could provide a drawing of your complete circuit maybe we could have input for it.
This is a continuation of my other random learning posts.
I'm attempting to use an arduino to control the speed of a 90vdc/1a motor based on the input from two optical encoders. I have the encoders working and I can update the PWM value as required.
In addition to controlling, I also need to provide power to the motor. Currently, I believe the motor is being fed with a ~120VDC. But I'm concerned about how that will effect the life of th emotor.
So I need to take the AC convert to DC. This seems to be an adventure.. At this point, we will assume that I buy a 90v power supply.
I need to take that power supply and interupt it with a mostfet to create the on duty cycle. At least that is my understanding.
Now since the arduino and the motor are using different power supplies.
I need to figured out how to make them play nice. I'm assuming that I can do this via a optoisolater.
But now, I run into the problem of trying to control the mosfet's gate. Without making magic smoke.
I would have thought that I could do all these alot easier than it has become. I'm starting to becoming a little disheartn.
Let me know if you have trouble, I have a similar circuit... I can take pictures for you..using 5v to switch the mosfet... and the mosfet is actually with 12v on the other end...
That's not completely case. And honestly, it boggled my brain a little bit. I need a pocket EE that I can tug on their shirt sleeve and ask for the english version of a definition.
I'm trying to understand how it will help me overcome the dual power supply issue. I don't understand how I can use the 90v supply to trigger a gate rated for 10-20 volts... or even 5. Without making smoke.
And I don't see how I can interupt the circuit on the motor with a mosfer that does not have a common ground with the circuit it's interupting.
Please excuse any obvious ignorance on my part. but be sure to point it out so I can overcome it.
