Please explain me the heating principle

djsfantasi

Joined Apr 11, 2010
7,689
o


It gets super hot when i connect it to the theater at 3v /2.7 A

How can i fix this problem
You were given the fix in post #10. Replace the MOSFET with an IRLZ24. Or similar n channel logic level MOSFET.

Just because you only have a different device doesn’t mean you can get it to work.

You asked for advice. Now follow it.
 

Thread Starter

Kadav

Joined May 11, 2018
158
You were given the fix in post #10. Replace the MOSFET with an IRLZ24. Or similar n channel logic level MOSFET.

Just because you only have a different device doesn’t mean you can get it to work.

You asked for advice. Now follow it.
yeah but the problem is i don't have it
 

DickCappels

Joined Aug 21, 2008
7,426
Excuse the question, I am not very knowledgeable about Arduinos, but is yours running at 3.3V or 5V?

Your MOSFET might be getting hot because it is not saturating -the whole point would be to have the entire power supply voltage drop across the drain load resistor, isn't it? If there is not a high enough gate voltage to cause the MOSFET to have a low resistance a the desired drain current, That can be helped by increasing the gate voltage, or a bertus suggests using a MOSFET with a lower characteristic gate voltage for saturation an the needed current.
 

Thread Starter

Kadav

Joined May 11, 2018
158
Excuse the question, I am not very knowledgeable about Arduinos, but is yours running at 3.3V or 5V?

Your MOSFET might be getting hot because it is not saturating -the whole point would be to have the entire power supply voltage drop across the drain load resistor, isn't it? If there is not a high enough gate voltage to cause the MOSFET to have a low resistance a the desired drain current, That can be helped by increasing the gate voltage, or a bertus suggests using a MOSFET with a lower characteristic gate voltage for saturation an the needed current.
yes it uses 5v , so how can i increase the gate voltage ?
 

andrewmm

Joined Feb 25, 2011
1,466
What do you know about FETs ?
They act here as a variable resistor.
if they are hard on or hard off, the resistance is either near zero or near infinity. In either state, the power dissipated is very low.

Look at the data sheet of the device you have used, it seems from the other reports, that you are not driving the FET hard on, so its not a low resistance, so its going to get hot.

To lower power, you need to drive it hard on,
to do that change the FET or the drive voltage ,

If you can't do that, then you have to get rid of the heat in a heat sink..
 

Thread Starter

Kadav

Joined May 11, 2018
158
It’s not going to work until you order the correct part..
Basically in context , i am working on a project that i have to finish , i am only using arduino starter kit , i would love to buy another product but i can't . and i don't have time for the presentations. so if i may get new ideas on how to do it . it will be a blessing
 

Thread Starter

Kadav

Joined May 11, 2018
158
What do you know about FETs ?
They act here as a variable resistor.
if they are hard on or hard off, the resistance is either near zero or near infinity. In either state, the power dissipated is very low.

Look at the data sheet of the device you have used, it seems from the other reports, that you are not driving the FET hard on, so its not a low resistance, so its going to get hot.

To lower power, you need to drive it hard on,
to do that change the FET or the drive voltage ,

If you can't do that, then you have to get rid of the heat in a heat sink..
Yeah i am trying the idea of driving more power . but my suggestion of combining 5v from power supply and 3v from arduino . i don't know it's a good one
 

djsfantasi

Joined Apr 11, 2010
7,689
Basically in context , i am working on a project that i have to finish , i am only using arduino starter kit , i would love to buy another product but i can't . and i don't have time for the presentations. so if i may get new ideas on how to do it . it will be a blessing
Besides a blessing, it will be a miracle, because it can’t be done.

I’ll be happy to be proven wrong.
 

andrewmm

Joined Feb 25, 2011
1,466
What do you mean by combine the 3v3 and 5v ?
If the arduino is outputting 3v3, then thats what you have.

You could change the power FET, change the arduino that has a higher output voltage or try using a smaller transistor that works off 3v3, to drive the power fet at 5v, preferabley more.
 

Thread Starter

Kadav

Joined May 11, 2018
158
What do you mean by combine the 3v3 and 5v ?
If the arduino is outputting 3v3, then thats what you have.

You could change the power FET, change the arduino that has a higher output voltage or try using a smaller transistor that works off 3v3, to drive the power fet at 5v, preferabley more.
i have a power supply that can supply 5v also
 

sparky 1

Joined Nov 3, 2018
541
James Prescott Joule studied and measured mechanical energy into power loss in (thermal units) this is Joules first law.
Coulomb used a straight forward approach his work is logical I find it reliable when things get strange.
"please explain heating principle" ok but without the quantum level or the many different mosfet, diac, control loop, comparators ect ect ect
For resistivity principle as in nichrome wire heating it works like this:

The standard industrial math used to order the correct material is like this:
https://temcoindustrial.com/product...sistance-and-non-resistance-wire/heating-wire
going further on this:
https://www.allaboutcircuits.com/textbook/direct-current/chpt-12/temperature-coefficient-resistance/

The question then becomes what level of precision is needed and why ? That could help determine the best choice. I see you have something in mind want the driver circuit to match the level shift and possibly an isolation circuit attached to an arduino.
 
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