Hi everyone,
I recently started learning about MOSFETs and wanted to use them to PWM control my ceramic heater on my 3D printer with 12v 3A (36W) Power supply. I found some MOSFETs that I think will be good for the purpose: NTD3055L104, NTD20N03L27, MTP3055VL, and IRLZ44PBF.
I will be connecting the MOSFET gate on digital PWM pin and I wish to control the Current or Voltage through MOSFET. The Ceramic heater will need around 40W to be at its full potential. Therefore, I need the MOSFET to allow full 12V and 3Amp through at 5V.
I also have a doubt. Does the MOSFET reduce the voltage or current, or does it convert some voltage into current.
Thank you
That's not how PWM works.
PWM switches the load fully ON/OFF say 500 times per second.
The ON/OFF ratio is the average power that the heating element consumes.
Leo..
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Ahh, okay. Thank you, Leo. So, can I use PWM with a MOSFET to switch it on and off really fast when it reaches the required temperature and switch it off slowly when it is below it? It won't ruin my ceramic heater, right?
Can I also generate a PID equation for the same?
I also found an old working MOSFET; its model is IRLB4132. Will it be usable with my circuit?
Thank you
Usually you change the duty cycle, not frequency.
But before you start switching anything, you need to verify that your heater is ok with your power supply. What are the specs for the heater, resistance?
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Hi Kmin. Sorry I meant duty cycle (thank you for clarifying that kmin). The heater requires 40W for its full potential. Its resistance is 6ohm. I have a 12V 3amp power supply that I will only attach to the heater.
Also, I found this datasheet for IRLB4132 MOSFET that I found.
Yes
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Hi jim-p. Just to clarify it will allow full 12V and 3amps through at just 5V on gate, right?
Also, a dumb question: Do I need to connect Arduino gnd to the mosfet source? As I already am connecting DC powersupply negative to it.
Thank you
Yes.
Do I need to connect Arduino gnd to the mosfet source?
Yes
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Also, I have a 10kohm resistor. Is it ok to use it as a pull-down resistor?
Thank you
How do you measure the temperature?
I have a 100Kohm thermistor that I will use with the voltage divider eq and another 100kohm resistor to find the voltage and then use its Beta value to calculate approx. temp.
Then I guess you are all set.
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Thank you everyone for all the help
FYI:
That MOSFET can easily handle up to 12A without a heatsink
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Oh ok. Thank you
Also, can I create a PID eq using a software for the same?
Be aware that the heating power of 6ohm resistor with 12V PSU is 24W, not 40W.
Its actually a ceramic heater not a resistor. Which, as per its specsheet, requires 40W at 12V for its full potential.
There are quite a few PID libraries for the Arduino, however I've never used any of them, so don't know which is the best. Do you really need PID?