Please explain me the heating principle

Thread Starter

Kadav

Joined May 11, 2018
126
Hello i have a heater that is 10W rating , that is all i know about the heater ,

I also know that it is a filament , which i guess that i can not connect on power supply directly , i have to connect it in series with a resistor to atleast heat , i connected it in series with a 1k resistor , and the power supply is drawing 10v and 6ma .

My question is how much time is it going to take to heat , and what can i do to make it heat more time .

should i increase the voltage ? or probably the heater is broken and i don't know ....

Thanks
 

Dodgydave

Joined Jun 22, 2012
9,207
10W at 10V is 1amp, you are drawing 6mA at 10V , that's 60mW!! ,

Take the resistor out and connect it directly to the PSU at it's correct voltage.
 

BobTPH

Joined Jun 5, 2013
2,435
Do you know the voltage rating if the heater? If so, connect that voltage or less directly to it.

If you dont know it, and you have a lab supply, you could connect it with the voltage set to minimum, then, monitoring the voltage and current, Raise the voltage slowly until the product (V • A) is equal to 10.

Bob
 

BobTPH

Joined Jun 5, 2013
2,435
Actually, looking at your numbers again, I think this heater is designed for 120V.

Your 6ma with a 1K resistor is 666 Ohms. That would be 20W at 120V, but the resistance would go up as it heats, so 10W sounds about right.

Bob
 

Thread Starter

Kadav

Joined May 11, 2018
126
Can you help me with this one now

I am driving the same heater 3v at 1.3 A and the arduino is a power MOSFET Of IRFZ0.

But it's not working it's only heating the mosfet but the heater is not heating , it looks like something is blocking the current to flow through because , without the arduino the heater heating at 3v 3Amps

thanks
1593435710109.png
 

bertus

Joined Apr 5, 2008
20,573
Hello,

Do you mean that you want to drive the heater with the 2N1711?
The heater has a stated current of 1.3 A, the 2N1711 can only drive 1 A (absolute maximum).
Better use a good logic gate mosfet.

Bertus
 

Thread Starter

Kadav

Joined May 11, 2018
126
Hello,

Do you mean that you want to drive the heater with the 2N1711?
The heater has a stated current of 1.3 A, the 2N1711 can only drive 1 A (absolute maximum).
Better use a good logic gate mosfet.
No i am using a IRFZ20 , but that is a nice point of view how do you see the current rating of a MOSFET
from this sheet(https://www.vishay.com/docs/91340/sihfz20.pdf) , it says drain current is 10A. I m not sure if i am correct

BUt is the wiring correct or i need to put a resistor somewhere ?
 
Last edited by a moderator:

Thread Starter

Kadav

Joined May 11, 2018
126
Hello,

Better change the IRFZ20 to a IRLZ24.
It can well be that the IRFZ20 will not be fully on at the voltage given by the Arduino.
The IRLZ24 needs less gate voltage to be fully on.

Bertus
Yeah but i have an irfz20 and it has a Cgs threshold of 4v and min the of 2 .
 

bertus

Joined Apr 5, 2008
20,573
Hello,

What is the output voltage of the Arduino?

The threshold voltage is the voltage where the current is about 250 μA.

sihfz20_data.png

You want a much higher current.

The IRLZ24 has a much lower threshold voltage:

IRLZ24_data.png

Bertus
 

bertus

Joined Apr 5, 2008
20,573
Hello,

The IRFZ20 can carry just over 2 A at Vgs = 5 Volts.
You are driving it at its limits, as the output of the Arduino will likely just a little bit lower as 5 Volts:

Atmega328_Voh.png

The IRLZ24 can carry 17 A at Vgs = 5 Volts.

Bertus
 

bertus

Joined Apr 5, 2008
20,573
Hello,

What is the supply voltage of the Arduino?
The absolute maximum voltage for the ATmega328 that is used in the Arduino is 5.5 Volts.

Bertus
 

Thread Starter

Kadav

Joined May 11, 2018
126
Hello,

The IRFZ20 can carry just over 2 A at Vgs = 5 Volts.
You are driving it at its limits, as the output of the Arduino will likely just a little bit lower as 5 Volts:

View attachment 210996

The IRLZ24 can carry 17 A at Vgs = 5 Volts.

Bertus
how do you determine that the voltage is 5v 2A . I would say it's 10 A .
But how do you read that
 

Audioguru again

Joined Oct 21, 2019
1,602
The curves on a datasheet are only for a Mosfet with typical spec's.
Where can you buy a Mosfet that has a typical saturation characteristic? Many of them conduct much less current when the Vgs is 5V. It is guaranteed to conduct only 0.00025A when its Vgs is 4V (its threshold voltage).
 

Thread Starter

Kadav

Joined May 11, 2018
126
o
The curves on a datasheet are only for a Mosfet with typical spec's.
Where can you buy a Mosfet that has a typical saturation characteristic? Many of them conduct much less current when the Vgs is 5V. It is guaranteed to conduct only 0.00025A when its Vgs is 4V (its threshold voltage).
It gets super hot when i connect it to the theater at 3v /2.7 A

How can i fix this problem
 
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