I am following this tutorial: http://diyhacking.com/arduino-lamp-dimmer/
For making a dimmer controller for a heater lamp (No light, just ceramic with a heat wire inside).
With this tutorial I can make my prototype work with a 40w lamp (light lamp) like a charm. But whenever I connect the heat lamp (100w) it fails. Arduino sends the right signal to the mosfet but this start smelling bad and can't control it. Temperature starts to get higher and higher.
I think it is because the watts this mosfet can dissipate is 74w and 100w is higher. I would want to find one for 300w at least or 500w because I would want to connect a heater lamp bigger in near future.
Can you recommend me a mosfet similar to irf830 but with better dissipation?
PD: Maybe the problem is another one. In that case, what would the solution be?
My guess is that your problem relates to the gate-source threshold voltage of that MOSFET.
You really need a "logic-level" MOSFET for it to switch fully on with an Arduino.
With 5V on the gate, the IRF830 won't be switching right on, so the Rds(on) will be quite high, resulting in excessive power dissipation.
I don't know where you buy your supplies, so can't recommend anything specific, but look for a MOSFET with a gate-source threshold voltage <2V.
What voltage are you working with? And I hope it's DC, and not AC. A MOSFET can't be directly used to switch AC of course.
Suriken:
I am using some arduino mini 3.3v to control the dimmer.
The threshold voltage for an IRF830 is 4V, and the actual voltage must be considerably higher than that for it to work well.
You still didn't say what voltage you're switching, and therefore we don't even know how much current either, making it impossible for anyone that does have any ideas to suggest a particular MOSFET. You'll need one with a very low Vgs(thr) to work well on 3.3V. Please verify that it is DC you're switching and not AC, too.
For supplies I was thinking on ebay. I usually buy everything there.
Perhaps you could do a Google search for "MOSFET 3.3V", then make a list of those that can handle the voltage and current that you're switching, then see if you can find any of those on eBay?
Edit: Perhaps you should post your schematic before going further, just in case. I haven't bothered hunting through the tutorial you're following trying to find it.
I am sorry. I don't know much about electronic. I don't know what you mean about the voltage I am switching. do you mean 220? it is an AC lamp at 220v.
Suriken:
I am sorry. I don't know much about electronic. I don't know what you mean about the voltage I am switching. do you mean 220? it is an AC lamp at 220v.
See my last post. Please post your schematic, rather than making us go hunting for it in tutorials. Obviously there's more going on than meets the eye if you're switching a 220VAC lamp with a MOSFET.
This sounds very much like it's a project that you should not be attempting if you have little or no electronics experience.
So, that schematic diagram please.
intledPin = 3;
void setup()
{
Serial.begin(9600);
Serial.println(“Serial connection started, waiting for instructions…n0 = Offn1 = 25%n2 =50%n3 = 75%n4 = 100%”);
}
void loop ()
{
if (Serial.available()) {
char ser = Serial.read(); //read serial as a character
//NOTE because the serial is read as “char” and not “int”, the read value must be compared to character numbers
//hence the quotes around the numbers in the case statement
switch (ser)
{
case ‘0’:
analogWrite(ledPin, 0);
break;
case ‘1’:
analogWrite(ledPin, 64);
break;
case ‘2’:
analogWrite(ledPin, 128);
break;
case ‘3’:
analogWrite(ledPin, 192);
break;
case ‘4’:
analogWrite(ledPin, 255);
break;
default:
Serial.println(“Invalid entry”);
}
}
}
Components:
Resistors: 330ohm(1No.s), 33k(2no.s), 22k(1No.s), 220ohm(1No.s)
Optocoupler: 4N35(1No.s)
Diode: 1N5408(4No.s) The one shown in the diagram, the list shows 4508,
1N4007(1No.s),
Zener 10V.4W(1No.s)
Capacitor 2.2uF/63V(1No.s),
220nF/275V(1No.s)
MOSFET: IRF830A
Well I was wrong about needing a logic-level MOSFET. I originally thought you were building a relatively low voltage DC circuit, with the MOSFET driven by the Arduino. My apologies.
But when you mentioned switching 220VAC with a MOSFET in reply #4 I expected to see a circuit like this. As a newcomer to electronics, I recommend that you forget it.
And you won't get it to work up to the power levels that you want anyway. The MOSFET can never be turned hard on, so will get very hot very quickly. No wonder you're having MOSFET failures.
Circuits of this nature are best left to the professionals.
So, even if I change the mosfet by another with better specs, I will keep having the same issues, don't I? I will try to find another way to achieve this.
I want to put those component inside a box and keep this working 24/7. It worked fine with a 40w lamp during a couple of weeks.
If I were doing it, I'd use a TRIAC with an opto-isolated TRIAC driver that incorporates zero crossing switching. That MOSFET/diode bridge method is crude, to say the least.
And really, newcomers to electronics shouldn't be trying to build mains powered circuitry without the benefit of a nice, safe, step-down transformer.
OldSteve:
And really, newcomers to electronics shouldn't really be trying to build mains powered circuitry without the benefit of a nice, safe, step-down transformer.
Agreed !! That is a good way to fry yourself or your equipment (or start a fire) - none of which are good things. Also your statement about wanting a 500 watt MOSFET for a 500 watt heater is not valid. The wattage rating of the MOSFET (or other control device) is the dissipation the device can handle with a proper heat sink and is determined by the voltage drop across the device and the current through it. The current through it is a function of what you are controlling, but the voltage across the MOSFET is a function of the control gate voltage and if it is in saturation or not. The important rating is the current through the MOSFET and the voltage being controlled - it must be rated higher than what you are controlling.
gpsmikey:
Also your statement about wanting a 500 watt MOSFET for a 500 watt heater is not valid. The wattage rating of the MOSFET (or other control device) is the dissipation the device can handle with a proper heat sink and is determined by the voltage drop across the device and the current through it.
I thought I'd mentioned this. I noticed that mistake in his thinking too.
I accidentally lost a lengthy reply last night, and I think I mentioned it in that one. (I was too lazy to try to remember everything and re-type it.)
OldSteve:
I thought I'd mentioned this. I noticed that mistake in his thinking too.
I accidentally lost a lengthy reply last night, and I think I mentioned it in that one. (I was too lazy to try to remember everything and re-type it.)
It's tough getting old (I'm there), but, on the other hand, I'm still on the right side of the sod, so all is good (and my wife lets me buy toys like these to play with).
gpsmikey:
It's tough getting old (I'm there), but, on the other hand, I'm still on the right side of the sod, so all is good (and my wife lets me buy toys like these to play with).
Haha. We need our toys.
Actually, you can really read this:-
I was too lazy to try to remember everything and re-type it.
OldSteve:
If I were doing it, I'd use a TRIAC with an opto-isolated TRIAC driver that incorporates zero crossing switching. That MOSFET/diode bridge method is crude, to say the least.
And really, newcomers to electronics shouldn't be trying to build mains powered circuitry without the benefit of a nice, safe, step-down transformer.
Thanks both of you.
You mean to implement something like this but with the correct elements:
I can't try anything this week until saturday but I will try to find components and some theory to read before that date.
