Hello, my son is trying to use a MOSFET with his Arduino nano. We are having trouble understanding how to hook up the MOSFET to his output pin. He is using a n channel MOSFET and he has the Arduino programmed to for pin 2 as the output. What he is trying to do is have the Arduino send an output to the MOSFET to send 9 volts from a 9v battery to ignite an Estes Rocket motor via a HM-10 Bluetooth chip. If anyone could assist in a wiring diagram that would be awesome!
Thank you!
I googled "N-channel mosfet as a switch" and this was the very first hit. Is this the diagram you need?
There is no shortage of examples of what you want in various topics on this forum, do some searching.
Which MOSFET exactly?
A common mistake is to use a MOSFET that is not logic level, which won't turn on properly with the 5V available on the output of an Arduino pin. Often (not always) logic level MOSFETs have L in their part number.
To make matters worse, cheap MOSFETs sold on popular retail websites are sold as 'Arduino compatible' and similar, but are not logic level.
It is a logic level MOSFET and it is a N channel
There are lots of N channel mosfets. Which one exactly? Did the diagram I linked you to not show what you needed?
The 9V gets from the MOSFET to the rocket via a Bluetooth chip? That doesn't sound correct. Most Bluetooth chips are 3.3V. They would be damaged by 9V.
I believe he has the Bluetooth sending a command to the Arduino then the Arduino sends the output to the MOSFET. I'm sorry I'm just trying to be the middle guy here... He's only 13 and I figured I'd ask a question on the forums to help him.
The MOSFET he has is a N channel RFP30N06LE
Thanks. And what exactly is the question about it again? At first you were asking for a diagram on how to use a mosfet as a switch. I showed you that. So there must be more to your query.
It's ok, I get it. But English, or any other natural language, is a really bad way to describe a circuit. For example, you didn't literally mean that 9V gets transmitted over Bluetooth, but it is literally what you said. That's always the problem with using natural language to describe anything technical.
The "natural" language of electronics is the schematic diagram. A picture says a thousand words, as the saying goes. But a schematic says a thousand words simply and unambiguously.
You don't have to use a fancy software app to produce one. Pencil and paper works just fine, as only as you keep it neat and tidy. If it looks like a spider's web, try again!
Tutorial on using that mosfet
http://adam-meyer.com/arduino/rfp30n06le-arduino
We looked over that tutorial and wired it like the picture... But we aren't getting anything from the MOSFET... When he builds it in Tinkercad and simulates it, it works... Is there something we might be overlooking? We have tested the code and pin output, we can see on the multimeter the output come on and go off according to the code he has written on it.
There are literally millions of things you could be overlooking. This would be so much easier if instead of asking us to GUESS what's wrong, you showed us what you have so we could maybe SEE what's wrong.
There are hundreds of posts like this a day that drag on for days with no help until finally someone posts the code or a picture or whatever and within five minutes the solution is there. It's hard to debug what you can't see. If you'll show it to us then someone can most likely help. If all you're going to do is say that it doesn't work then all I can hazard as an answer is that you did it wrong.
I'm sorry for making it confusing... I have uploaded a picture of the tinkercad design he is using. The light bulb would be the Estes rocket ignitor... He has the supply coming from the ground on the Arduino nano and the gate from pin 2... Between both of them is a 10k resistor. Then his drain is going to the ground of the bulb/ignitor and the other side of that is the voltage lead from the 9v battery. His code is to send output from pin 2 for 5 seconds... That output will be told to send it's output via a Bluetooth chip he will be wiring up via the Rx & Tx wires. All that works fine but we are stuck on this MOSFET. The Estes ignitor needs at least 6v DC to burn. When we are testing we are using a multimeter in-between where the ignitor would be, we aren't seeing and voltage when sending the command. But can see voltage going to the MOSFET and confirm output from pin 2.
Is that the square kind of 9V battery like in the picture? They can barely make enough current to light a light bulb. I doubt they have enough for that ignitor. People love to sell kits with the little clips for them, but they're crappy batteries for anything that needs any current.
Try a group of 4 AA batteries and see what that does.
Do you have specs on the ignitor? Is the 9V battery also powering Arduino? Can you take a picture of the actual setup? Maybe you have something connected funny.
When the mosfet is supposed to be On, what are the voltages on the gate, drain and source with respect to ground?
While the Arduino is sending the output the gate is showing .4 volts, and the source is ground, the drain is nothing.
If your sketch was generated with an AI like ChatGPT or by someone else tell us in your post.
When you follow the posting guidelines, volunteers can be more effective.
Maybe something is wrong in the code. You should probably show that too.
It's really hard to debug stuff that you won't show us. Just go ahead and get it all out there and save us all a lot of time.
The threshold gate voltage of the mosfet is about 1.5V. So .4V wouldn't turn it on at all. But if you see 5V on D2, and if D2 is connected directly to the gate, why is the gate only .4V? It should be 5V too.
I don't know about the igniter, but in the diagram showing the lamp, the lamp is just a low-value resistor. So if the mosfet is actually off, the drain should be at 9V. When the mosfet is on, the drain should be near 0V, and the lamp should be lit.
