I am trying to heat up resistors at different timing intervals. Currently I am using 10 Ohm resistors, each connected to a different digital pin on the Arduino. However, they are not heating up as if I were to connect them to the 3.3V or 5V pins. Any suggestions?
And where did you learn that the Arduino Digital pins will happily supply half an Amp of current each?
OR, are we to assume that when you state that you have 10 Ohm resistors connected to a digital pin that you actually mean that they are hooked up to some kind of driver CONTROLLED by a digital pin?
Please share your wiring diagram
And where did you learn that the Arduino Digital pins will happily supply half an Amp of current each?
I never said that I thought each digital pin supplied half and Amp of current. Sorry I could have worded it better. What I am trying to do is heat up each resistor as if I was trying to turn on different LED's, each of which connected to a different pin. However, when looking at the spec's of the UNO, I know that each Digital pin supplies 20mA. I already know when I connect a 10 oHM resistor to the 3.3V pin it begins to heat up. So I thought maybe increasing the current output of each pin could maybe help?
LPDE:
I never said that I thought each digital pin supplied half and Amp of current.However, when looking at the spec's of the UNO, I know that each Digital pin supplies 20mA.
I already know when I connect a 10 oHM resistor to the 3.3V pin it begins to heat up.
So I thought maybe increasing the current output of each pin could maybe help?
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You are only trying to do so.
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Wrong. The pin supplies 5volt.
Current will only flow when you connect a load to the pin.
When you connect a load with 10ohm resistance, then 5volt / 10ohm = 0.5Amp wants to flow.
The pin can't supply that, and the pin voltage will collapse.
And possibly damage the transistors in side the chip. -
The 3.3volt pin (of an Uno) can supply more than a pin.
About 150mA.
You are trying to extract 3.3volt / 10ohm = 0.33Amp = 330mA from that 3.3volt regulator.
Overloading it more than two times.
That regulator chip will die shortly too. -
You need external transistors to switch bigger loads.
Then the Arduino only has to deliver a much smaller base current.
Or only a gate voltage if you're using a fet.
But that big current has to come from somewhere.
Hopefully not from Arduino's 5volt pin.
Try to get a better understanding of Ohm's law before you set off frying things.
Leo..
The output pins don't give you a current. They give you a voltage. And they also specify a maximum current. But it's up to you to not go passed that current. If you do, you'll probably damage the Arduino. And a 10Ohm resistor will draw halve an amp at 5V so that's way over that given limit you had to watch 
- The 3.3volt pin (of an Uno) can supply more than a pin.
About 150mA.
You are trying to extract 3.3volt / 10ohm = 0.33Amp = 330mA from that 3.3volt regulator.
Overloading it more than two times.
That regulator chip will die shortly too.
Ah I see now, so I should really be using a 22 Ohm resistor when connected to the 3.3V to be on the safe side? I can already tell that the resistor doesn't heat up as fast.
You need external transistors to switch bigger loads.
Then the Arduino only has to deliver a much smaller base current.
Or only a gate voltage if you're using a fet.
This approach sounds like what I'm looking for. Is there any examples available that I could look at using transistors as I already have some?
read about an XY PROBLEM
then post what you really want to do.
and, at what temperatures you are trying to achieve.
I would wager that heating resistors in leau of turning on LED's is not your goal.
I can assure you that you will not be heating 10 ohm resistors to anything like 'hot' that are directly coupled to an output pin of an Arduino.
if you are after heat, then I would offer that some solid familiarity with OHM's law, especially when used to determine amperage and to determine wattage would be in order.
LPDE:
This approach sounds like what I'm looking for. Is there any examples available that I could look at using transistors as I already have some?
google arduino transtor.
you can put arduino into any search term
and you can find a diagram for a relay and swap our resistor for a relay in those sketches.
for help from us, you would need to tell us what part numbers you have. pick any one of the ones you have to get started.
then post what you really want to do.
and, at what temperatures you are trying to achieve.
How do I heat 3 resistors in turn at a temperature of around 50 degrees Celsius?
and you can find a diagram for a relay and swap our resistor for a relay in those sketches.
Like this:
and
https://learn.sparkfun.com/tutorials/transistors/applications-i-switches
?
Have you read the XY problem thing?
And ever used Google?
Heating something with a resistor is pretty easy. Precisely controlling the temperature of something is not...
google arduino transtor.
you can put arduino into any search term
and you can find a diagram for a relay and swap our resistor for a relay in those sketches.
Sorry if I am being confusing but if I type in 'Arduino transistor' I don't find anything with a relay.
Heating something with a resistor is pretty easy.
An example would be helpful?
Here's an example.
Buy the transistor at Digikey.com
The low Rds means it will dissipate very little power and stay nice & cool.
At 1.2A for example and 5mOhm Rds, it will dissipate just 7mW.
LPDE:
Sorry if I am being confusing but if I type in 'Arduino transistor' I don't find anything with a relay.
I typed
Arduino transistor
into google and THE TOP HIT was:-
https://www.arduino.cc/en/Tutorial/TransistorMotorControl
A relay and a motor are electrically the same thing. You just don't need the diode if you are using a resistor.