Hello,
I would like to know if this coil heating module 5v-12v can be operated by Arduino mega?
if yes, can I use PWM to control it? depending on the duty cycle? and how the code should be.
I would like to use it for heating an air inside the box to remain a temperature stable.
Thank you.
Ýes, but no PWM. It's already switching to drive the coil. If you know the schematic you might be able to hack into the oscilator and control it from an Arduino as well in some sort.
If you just want to control the output power to heat stuff you can do it by switching it off and on. I don't call this PWM because I mean on and off for some seconds. This is how electric stoves and heaters do it. Because something will not cool down instantly it kind of levels out.
What are you using for temperature feedback
?
I wouldn't buy it because there are no specs or application information... Or, did you find the specs somewhere?
...There's not even a wattage or amperage spec.
Heat is directly proportional to power (Watts) and power is the product of voltage x current. For example, a 120V / 1200W hair dryer requires 10A. A 12V / 1200W hair dryer would require 100A!
The most straightforward way to make a heater is to use a [u]power resistor[/u] (or multiple power resistors). If you know the voltage & desired wattage, you can calculate the resistance (Ohm's Law and the power formula). Then, choose a resistor with about double the power rating so you don't push it to it's limits.
Or you can use [u]Ni-Chrome[/u] wire, shich has a certain Ohms-per-foot (or per-meter) resistance depending on the wire gauge. Hair dryers, toasters, soldering irons, etc., are made with Ni-Chrome Wire.
You'll have to guess & experiment to find the required power. It depends on the outside temperature, the size of the box and how well it's insulated. And it might depend on how fast you need to heat it, if that's important to you. So rather than measuring the insulation (thermal resistance) and doing a bunch of complicated calculations & estimations, it's easier to stick a heater/resistor inside to see how much heat rise you can get with 5 or 10W, or whatever.
PWM is rarely used with heaters, ovens, toasters, air conditioners, refrigerators, etc. Since the heat can't change instantly, your heater switches-on whenever it's too cold, and then switches-off when the target temperature is reached. (With a little "swing" or hysteresis so it doesn't switch on & off several times per second.)
Great write-up by DVDoug!
I would add one thing: Ways of driving the Power Resistor(s) or NiChrome wire [hereafter referred to as the Heater or Heating Element], since in most cases an Arduino output will NOT be able to source or sink the required current AND/OR if the voltage supplied to the Heating Element is greater than +5.
OK, one other thing: How about using a thermistor to implement a control loop. Use the Arduino to turn on the heating element until, via the thermistor, a target temperature is reached. In which case, turn the heating element off. And, as DVDoug suggested, have two "set points", one slightly higher than the other such that, the heater is left on until the temperature reaches the first set point, then turn it off until the temperature falls to the second set point. The difference between the two temperature set points, is called the "deadband" and causes a hysteresis effect. The smaller the deadband, the more often the heating element will cycle.
In the attached schematic, a MOSFET drives the Heater, and the Thermistor is the upper part of a voltage divider, and the voltage at H3 varies with temperature. Since you didn't divulge the target temperature (in the box), you will need to select an appropriate thermistor, OR if it's a temperature so high that no thermistor will suffice, then consider a thermocouple or other means of determining the temperature.
The values and Jameco part numbers are merely suggestions. Choose a "Logic Level" MOSFET that can easily handle the current required to drive the heater. The suggested RFP12N10L is a 100V device that can handle up to 12Amps (though, a heat sink may be required at currents that high). I selected it because it's low cost (only 79 cents), yet has some beef to it.
R1 is to limit current in cases where the MOSFET's input capacitance is high enough to cause an inrush current that might damage the Arduino output. 1/4 Watt is fine.
PWM is rarely used with heaters, ovens, toasters, air conditioners, refrigerators, etc. Since the heat can't change instantly, your heater switches-on whenever it's too cold, and then switches-off when the target temperature is reached. (With a little "swing" or hysteresis so it doesn't switch on & off several times per second.)
I have read this or heard it said many times, and it seem like it should be obvious but apparently not.
The argument against PWM control of heating is specifically relevant when the system supply is AC since the PWM will be chopping the sinusoidal waveform and creating masses of harmonic noise. In such cases 'burst' control is normally used whereby the power is switched on and off for several (or many cycles) and should be switched at the zero crossing point to minimise noise.
If you are using DC as a supply source then PWM is perfectly suitable for driving an oven type device. In fact it's actually better than burst control since the overshoot and hysteresis can be minimised by using suitable PID control.
When you consider that a DC motor's power output is normally controlled via PWM there is absolutely no difference in replacing the motor with a power resistor.
By way of example, a 50watt resistor running at 50% PWM will output 12.5watts (50% mean voltage and 50% mean amps = 25% mean power)
Uhmm, no. If at full load it's 50W it's 25W @ 50% duty.
Instantaneous power is given by:
P(t) = U(t) x I(t)
Average power is:
For a 50% duty cycle that's the same as T = 1, Ton = 0,5 and Toff = 0,5. Filling that in gives:
And that's why we use RMS (although mostly for sinusoidal AC). So you could still use:
Pavg = URMS x IRMS
For the above PWM for example with 5V and 10A:
And 3,54V x 7,07A = 25W again 
GREAT REFRESHER COURSE !
Deleted by author
Is that an INDUCTION heater designed to heat ferrous objects like steel bars or bearings by magnetic eddy currents? If so, it won't heat air.
Induction Heater
septillion:
Ýes, but no PWM. It's already switching to drive the coil. If you know the schematic you might be able to hack into the oscilator and control it from an Arduino as well in some sort.If you just want to control the output power to heat stuff you can do it by switching it off and on. I don't call this PWM because I mean on and off for some seconds. This is how electric stoves and heaters do it. Because something will not cool down instantly it kind of levels out.
No, I don't have a schematic.
Ummm yes I want to control the output but not only on/off.
Thank you so much.
raschemmel:
What are you using for temperature feedback
?
A thermistor sensor, 10k ohm.
raschemmel:
I have read this or heard it said many times, and it seem like it should be obvious but apparently not.
Um, so you advise me to do this ?? an on/off switch.
In that case, I won't be able to control it accurately. because I want the temperature to be stable at 37 degrees.
if more then 38 degrees the heat should be off, if less than 36 degrees the fan should be off.
but I want something heats 37 and can control the heat change with decimals.
such as if the desired 37 and the actual 36.5. I want it to increase the heat so it comes 37.
Thank you so much
DVDdoug:
I wouldn't buy it because there are no specs or application information... Or, did you find the specs somewhere?...There's not even a wattage or amperage spec.
Hello dear,
Thank you so much for your reply
I have seen videos and other websites that sell and describe it.
DVDdoug:
Heat is directly proportional to power (Watts) and power is the product of voltage x current. For example, a 120V / 1200W hair dryer requires 10A. A 12V / 1200W hair dryer would require 100A!The most straightforward way to make a heater is to use a [u]power resistor[/u] (or multiple power resistors). If you know the voltage & desired wattage, you can calculate the resistance (Ohm's Law and the power formula). Then, choose a resistor with about double the power rating so you don't push it to it's limits.
Umm, I don't really know the watts and voltage, but I want if to be stable at 37 degree.
DVDdoug:
Or you can use [u]Ni-Chrome[/u] wire, shich has a certain Ohms-per-foot (or per-meter) resistance depending on the wire gauge. Hair dryers, toasters, soldering irons, etc., are made with Ni-Chrome Wire.You'll have to guess & experiment to find the required power. It depends on the outside temperature, the size of the box and how well it's insulated. And it might depend on how fast you need to heat it, if that's important to you. So rather than measuring the insulation (thermal resistance) and doing a bunch of complicated calculations & estimations, it's easier to stick a heater/resistor inside to see how much heat rise you can get with 5 or 10W, or whatever.
PWM is rarely used with heaters, ovens, toasters, air conditioners, refrigerators, etc. Since the heat can't change instantly, your heater switches-on whenever it's too cold, and then switches-off when the target temperature is reached. (With a little "swing" or hysteresis so it doesn't switch on & off several times per second.)
the box is made of wood and acrylic, it's around 25 cm * 25cm insulated.I need this to be a simulation of the baby incubator. I need something gives a heat and able to be controlled with small changes, the decimals.
as I mentioned in my previous post does this Ni-chrom work?
thank you so much
Then you need a simple resistive heating element driven by a PID controller
How many watts of heat ?- you need to consider the thermal transmission properties of the enclosure walls, including top and bottom, (watts per degree differential per square metre), the surface area of the enclosure, the range of external ambient temperatures and the desired controlled internal temperature.
jackrae:
The argument against PWM control of heating is specifically relevant when the system supply is AC since the PWM will be chopping the sinusoidal waveform and creating masses of harmonic noise. In such cases 'burst' control is normally used whereby the power is switched on and off for several (or many cycles) and should be switched at the zero crossing point to minimise noise.If you are using DC as a supply source then PWM is perfectly suitable for driving an oven type device. In fact it's actually better than burst control since the overshoot and hysteresis can be minimised by using suitable PID control.
When you consider that a DC motor's power output is normally controlled via PWM there is absolutely no difference in replacing the motor with a power resistor.
By way of example, a 50watt resistor running at 50% PWM will output 12.5watts (50% mean voltage and 50% mean amps = 25% mean power)
Umm, I am thinking of replacing the control of heat element by the control of fan, using PID control only if I give up from controlling the heating element.
jackrae:
Then you need a simple resistive heating element driven by a PID controllerHow many watts of heat ?- you need to consider the thermal transmission properties of the enclosure walls, including top and bottom, (watts per degree differential per square metre), the surface area of the enclosure, the range of external ambient temperatures and the desired controlled internal temperature.
What do you suggest as a resistive heating element? I don't know how many watts will be good. in this project we will regret the transmission properties as a noise.. we need only to focus on the air desired and actual temperature,
thank you so much
A thermistor sensor, 10k ohm.
What is the operating temperature range for the heater ?
ReverseEMF:
Great write-up by DVDoug!I would add one thing: Ways of driving the Power Resistor(s) or NiChrome wire [hereafter referred to as the Heater or Heating Element], since in most cases an Arduino output will NOT be able to source or sink the required current AND/OR if the voltage supplied to the Heating Element is greater than +5.
OK, one other thing: How about using a thermistor to implement a control loop. Use the Arduino to turn on the heating element until, via the thermistor, a target temperature is reached. In which case, turn the heating element off. And, as DVDoug suggested, have two "set points", one slightly higher than the other such that, the heater is left on until the temperature reaches the first set point, then turn it off until the temperature falls to the second set point. The difference between the two temperature set points, is called the "deadband" and causes a hysteresis effect. The smaller the deadband, the more often the heating element will cycle.
In the attached schematic, a MOSFET drives the Heater, and the Thermistor is the upper part of a voltage divider, and the voltage at H3 varies with temperature. Since you didn't divulge the target temperature (in the box), you will need to select an appropriate thermistor, OR if it's a temperature so high that no thermistor will suffice, then consider a thermocouple or other means of determining the temperature.
The values and Jameco part numbers are merely suggestions. Choose a "Logic Level" MOSFET that can easily handle the current required to drive the heater. The suggested RFP12N10L is a 100V device that can handle up to 12Amps (though, a heat sink may be required at currents that high). I selected it because it's low cost (only 79 cents), yet has some beef to it.
R1 is to limit current in cases where the MOSFET's input capacitance is high enough to cause an inrush current that might damage the Arduino output. 1/4 Watt is fine.
actually yes that's what I was thinking about, considering the maximum degree(38), minimum degree(36), and the difference between the actual air temperature (a) and the setpoint temperature. (s)
where above the max, off, level 0% or a-s>= 1 degree
below the min on, the highest level 100% s-a>= 1 degree
if a-s< 1 degree on, level 25%
if s-a< 1 degree on, level 75%
if a=s on, lever 50% which should be the default at start.
and yes, I am using thermistor 10k ohm as a temperature sensor,
will the NI-chrom wire going to work in this case ?
thank you.
raschemmel:
What is the operating temperature range for the heater ?
between 36 and 38 degrees
septillion:
Uhmm, no. If at full load it's 50W it's 25W @ 50% duty.Instantaneous power is given by:
P(t) = U(t) x I(t)Average power is:
For a 50% duty cycle that's the same as T = 1, Ton = 0,5 and Toff = 0,5. Filling that in gives:
And that's why we use RMS (although mostly for sinusoidal AC). So you could still use:
Pavg = URMS x IRMSFor the above PWM for example with 5V and 10A:
And 3,54V x 7,07A = 25W again
I thought it's 30 watts at 5 volts, Thank you for your explanation!!
could you please explain me the RMS? how can I apply it?
Thank you
outsider:
Is that an INDUCTION heater designed to heat ferrous objects like steel bars or bearings by magnetic eddy currents? If so, it won't heat air.
Induction Heater
Ummm I don't know if its only for objects,
between 36 and 38 degrees
Why aren't you using a DS18B20 sensor ?
They are much easier and more accurate than a thermistor.
