MOSFET IRF840 DRIVER DOWNLOAD
Once I did these things, the resistance seemed to drop to zero when I applied 5V to the gate. I didn’t have any luck with the transistors that got from Radio Shack, I actually just ended up getting the original IRFs that I had to work by using 4 in parallel to prevent them from overheating. Have you got a potentiometer to hand, maybe 1K? Both lowered resistance, but still kept maybe 2k ohms. You alo need to check the data sheet to see how well it performs with only 5v on the gate. You might need something to increase the gate voltage for lower internal resistance.
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Then try supplying the NPN base from the arduino pin.
Both lowered resistance, but still kept maybe 2k ohms. Another problem you have is that the IRF has an enormous Ron of 0. Have you got a potentiometer to hand, maybe 1K?
You alo need to check the data sheet to see how well it performs with only 5v on the gate. If not, what do you do, and again, what are the proper components to use?
My problem is that it never seems to be in an off state, as soon as Moosfet connect the power, the pump turns on and the MOSFET gets really hot. You simply need to drive its gate from a NPN transistor with pull-up to 12V – however the pump might be putting spikes onto the 12V rail which might be an issue.
Do you do what I did and turn the power on and off really fast? If so, what are proper components to use? So my next question is what is the proper method for giving a motor more and less power? The water pump is rated at 12V and 2. Tying the gate to the source with ief840 high value resistor is a good plan as people have mentioned, such as 1Mohm, so that its safely off until setup has run.
Perhaps I should post this in a separate topic, but it is a continuation of the project addressed above and may relate to the way that I am using power. I’ve krf840 an actual picture of what I’m working with. This happens even if I don’t even have the Ardunio hooked up.
Mksfet, I have no idea how to properly use a PNP transistor, I attempted to run the 12V through the PNP and use the Arduino’s 5V to turn it off an on, however this did not seem to work and I ran into all kinds of crazy issues such as power seeming to run back through the gate from the collector.
I’m having some very weird issues with using PWM analogWrite and the delay function. This apparently produces a 1V signal.
Trouble with MOSFET
This is the source code that I used: I didn’t have any luck with the transistors that got from Radio Shack, I actually just ended up getting modfet original IRFs that I had to work by using 4 in parallel to prevent them from overheating. And Arduino doesn’t have high-voltage tolerant output pins. You might need something to increase the jrf840 voltage for lower internal resistance.
MarkT Brattain Member Posts: Remember MOSFETS have an effectively infinite input resistance so if the gate is left floating it will pick whatever ions are floating around in the air, respond to any slight leakage currents that might be present. Here is the part of the code where the delay is not working, I set it up to eliminate any outside factors: The last problem that I had was that the thing would overheat pretty bad after a just a few moments of the motor being on. I solved this by simply adding 3 more IRF’s in parallel.
Also of note is that the delay function seems to work just fine if I remove the PWM pin so that it is not connected to anything.
I combed over the code because oftentimes problems like this are due to coding errors, but I have not been able to find any problems in the code. This is its listing on Ebay: I maybe could have solved this with proper use of diodes, but after jrf840 few hours of messing around, I was still stumped. I thought I’d post an update since everyone was so helpful.
Once I did these things, the resistance seemed to drop to zero when I applied 5V to the gate. I went to Radio Nosfet today and picked up a few things that I thought would be helpful and help get me ahead of where I was yesterday: I found that “analogWrite 9, ” worked better. Something rated V and A and with logic-level drive would be much more useful to you