Ambient EM fields can easily affect it, and with nothing connected the voltage can fluctuate and take on just about any value. Yes, 47 or ohms in series with the gate is a good idea, as are the s. If so, what value would be good? The motor runs away. I’ve got a 12V 1.

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The FET still gets very hot as well. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Aula 8 – Controlo Motor 24VDC MOSFET IRF | engenhocas4you

Should I keep increasing the Capacitor? Currently I am using a ohm gate input resistor, It is working fine. The diode is across the motor to prevent current flowing back when the motor is switched off and still turning. Why does the get hot when the doesn’t?

What are the specifications of your motor esp. I’ve got a diode in place between the drain and source to prevent the flow of current when the motor switches off. Post as a guest Name. The drain and source are supposedly not connected if there is no moor voltage applied and thus the motor should not spin but it does spin I’ve connecting it correctly, just the standard way that is found all over the internet.


I have done experiments increasing the gate voltage until the drain voltage changed no more and found 8 volts met this requirement. There are too many people showing us cartoons in their questions instead of schematics already.

I know about heat sinking and current protection circuits but sometimes this still happens. Rif540 going to be interesting finding out.

Thank you for your answer I was thinking of ohms so I am way under the maximum you have given me. The middle pin should go to the motor.


Sign up or log in Sign up using Google. Two small transistors is better. With the IRL, the circuit runs away. My question is thus: By using our site, you acknowledge that you have read motpr understand our Cookie PolicyPrivacy Policyand our Terms of Service. Your transistor is getting hot because it is not turning on all the mltor. Look at the 10K resistor in the pictures below: So, I tried increasing the C2 to 1uF electrolytic and it started rotating.

The Arduino’s 40mA output maximum per pin is not going to be an issue. Hi, After spending a lot of time working with the Raspberry Pi in its mootor guises, I got hold of a copy of Getting Started with Arduino.


The resistor ensures there is always a known state, and only an active output HIGH from the Arduino will cause it to actually turn on. By “no gate voltage applied”, I assume you’re not driving it – it’s unconnected, or connected to mktor impedance such as an input pin.

Do you have a NPN transistor ex: The text I’m working from recommends the IRF series. Post as a guest Name.

The IRF works with much lower light levels, with and without the pulldown resistor. Would it actually destroy the purpose of controlling motor speed with PWM? Can you increase your gate voltage to 10V minimum? This is why you ,otor always have a pullup or pulldown resistor on your MOSFET’s gate if there’s any chance it might be otherwise undriven.