I am more or less new to microelectronics but i really love to learn and create, so with the intro out of the way please forgive me for my ignorance and limited knowledge.
I want to create a DIY yogurt machine, i already have a 24v 200watt silicon heater and an arduino nano. What i am missing is a mosfet that could control the silicon heater over arduino with PWM.
Please if anyone has any mosfet to suggest or at least tell me what i have to look for in the data sheets to minimize my search scope. Let me also know if driving the silicon heater with that power consumption is even possible with a mosfet, i would like to avoid a mosfet driver if possible.
What? The MOSFET has to be part-of a driver circuit.
200W / 24V = 8.3 Amps so your MOSFET should be rated for ~10Amps or more and it will probably need a heatsink.
Another option is a relay, but then you'll need a relay driver circuit. You can buy "relay boards" with a built-in relay and driver. Relays don't work with PWM but....
PWM is not normally used with heating or cooling. The temperature can't change instantly so normally power is switched-on if the temperature is below-target, and off when it's above-target. That's how the heater in your house works and how your refrigerator works, etc.
There is also normally some "swing" or "hysteresis". That means it goes a little over-target before switching off and slightly below-target before switching on again. (It can be 1/10th of degree or something like that, if it's critical.) That way it's not turning-on & off several times a minute or several times a second. That's OK with a MOSFET but you don't want a relay to "chatter".
I think i expressed myself wrong. What i meant by "mosfet driver" is actually gate driver, i would prefer the mosfet to be Logic Level so i can directly hook it up to arduino.
Ok thanx for the advice will avoid PWM, anything else i should pay attention to besides the current rating of a mosfet?
For starters i plan on using a thermistor with PID control over arduino, i am not sure how accurate the thermistor will be, i really need to have stable temperatures since the yogurt fermentation process requires a stable and precise temperature.
I just noticed that IRF3708 can operate RDS on @10v, but can still output enough amps for my project even at 4.5v does that affect the operating temperature of the mosfet itself? Avoiding a heatsink would be ideal.
I would like to have it at least prototyped in its basic form to make further plans, this is my 1st project that will have some useful application. If you have any suggestions regarding EMI filtering i would love to hear it.
It's extremely difficult and complex. What I am actually saying is, don't do it. Your "useful application" might not be so useful if it interferes with, for example, emergency communications like fire and ambulance services, or broadcast radio.
Look for some engineered module that handles all that for you.
I think you got it wrong, i just want to make some yogurt for myself to eat
I am not going to sell it. I just want something basic that will keep a stable temperature for 6 hours.
Based on you logic noone should ever prototype anything cause we might interfere with emergency communications, please this is not helping me in any way. I am not against creating safe stuff, i am all in for that and like i said, if u have any suggestions then go ahead and let me know what do u have in mind, your advice of "dont do it" is not helping me in any way.
Good lord i am just trying to create a basic arduino PID controlled temperature device.
