i found an example where a potentiometer was connected to
+5V, GND and A0 on a arduino uno.... i tryed the same, butt
my potentiometer (0,25W) died.
my question: do i need a potentiometer for more Watt or did
i made a mistake in the circuit ?
I do this all the time using 10K pots. Wattage is extremely small (way less than 1/8 watt). So you must have either hooked it up wrong or used a too small resistance.
Make sure the wiper (usually pin 2 on the pot) is connected to the A0 pin and you can't really go wrong.
but am i wrong ?
at a 10k poti the resistance on the wiper is between 0 and 10000 ohm ?
You are correct. However if you miswired the pot into a circuit such that the wiper is wired to ground or +5vdc and one end or the other end of the pot is also wired to +5vdc or ground, then you can create a short circuit condition between the wiper and one end of the pot when the pot is turned to one extreme position. How you are wiring up the pot is the problem, not the pot itself.
ok, i tested the poti in on a fresh breadboard and it works.
on the new breadboard the ARef is conn. to +5V. maybe
thats the different.
now i will test the poti in the complete circuit of the PCB
(this time with conn. ARef).
i will report if it DONT work. otherwise thanks for help
on the new breadboard the ARef is conn. to +5V. maybe
thats the different.
No, you should not connect th ARef to anything.
Can't you face the fact that while you knew what to do correctly, when it came to actually doing it you got it wrong? That happens all the time in electronics to everyone, even me!
Don't connect ARef to anything, it is not needed and could potentially damage your arduino.
You smoked your pot because you wired it up wrong, plane and simple. The fact it works now is that you have it wired up right now.
somewhere i read that without a connection to ARef
the Atmega uses a 1.1V Ref.Voltage.
You either miss understood it or it was rubbish.
The value of the reference voltage has absolutely no affect on your pot. If you used a lower VRef and 5V on the pot all that would happen is that the maximum reading would be reached sooner in the rotation.
somewhere i read that without a connection to ARef
the Atmega uses a 1.1V Ref.Voltage.
Maybe this is why my poti smokes if i use it with 5V.
Your read wrong, or misunderstood what you read. For normal analogRead functions where you are reading a DC voltage between 0 and +5vdc applied to a analog input pin, you should have nothing wired to the Aref pin. Miswiring the Aref pin can also cause internal damage to the chip and should be used only when you fully understand the why and how of using external reference voltages for the arduino chip.
Posted on: November 12, 2011, 05:33:35 PM
Posted by: Frank Burns
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ok, i tested the poti in on a fresh breadboard and it works. on the new breadboard the ARef is conn. to +5V. maybe
thats the different.
now i will test the poti in the complete circuit of the PCB
(this time with conn. ARef).
i will report if it DONT work. otherwise thanks for help
Posted on: November 13, 2011, 05:21:57 AM
Posted by: Frank Burns
Insert Quote
ok, it works.....
the only thing i done is to connect ARef with +5V.
somewhere i read that without a connection to ARef
the Atmega uses a 1.1V Ref.Voltage.
Maybe this is why my poti smokes if i use it with 5V.
Do you know what you have or are you changing things and not saying until later?