I was making an Arduino project. It was a very safe project as I copied it from Arduino's official website. The project was about adjusting the speed of blinking the LED on 13 pin of the Arduino.

I connected the potentiometer correctly as shown in the circuit diagram. Firstly the project was working fine, but after some time smoke started to come out from one of this pins - A0 , GND and 5V. I removed the power cable quickly. There was no damage to the board.

My questions are -

  1. What is the reason behind this smoke?
  2. Can these pins be used further? (I really removed power cable quickly.)

Project - https://www.arduino.cc/en/Tutorial/AnalogInput

circuit diagram below

Thanks in advance.



closed as unclear what you're asking by Chris Stratton, winny, Voltage Spike, MCG, Dmitry Grigoryev Jun 14 '18 at 6:26

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  • 3
    \$\begingroup\$ What value is the pot? \$\endgroup\$ – winny May 29 '18 at 6:01
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    \$\begingroup\$ What was the Ohms value of the potentiometer? The arduino.cc AnalogInput tutorial doesn't specify a value, but using a very low resistance value will draw excessive supply current (Ohm's law). Smoke is a sure sign that something overheated, melting insulation or burning an IC's expoxy coating, so it's very likely that something was permanently damaged. Do you have a DVM or an oscilloscope for debugging? \$\endgroup\$ – MarkU May 29 '18 at 6:02
  • \$\begingroup\$ I removed it from a lamp dimmer that have rating of 220V 60htz. \$\endgroup\$ – pra9 May 29 '18 at 9:53
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    \$\begingroup\$ That’s not a resistance value. Please measure it with s multimeter or read the markings on the pot. Also, are you sure it’s an potentiometer and not a rheostat? \$\endgroup\$ – winny May 29 '18 at 10:23
  • \$\begingroup\$ I've never seen smoke coming out of pins, and I doubt it's possible unless your pins are made of plastic. \$\endgroup\$ – Dmitry Grigoryev Jun 14 '18 at 6:25

I found my answer. My pins are working fine I don't know how but they are working fine. And answer to second question-

I found three killer who tried to kill my arduino-

  1. Arduino.cc - As they did't instructed properly.

  2. light dimmer - That dimmer don't have any indication of high and low resistance. As well its potentiometer also don't have any markings.

3.Me - Its my mistake that I did't calculated its resistance and the biggest mistake that for sometime I set the value to zero ohms' And the current crossed the limit of 40mA.

  • \$\begingroup\$ If you found the answer you needed, please accept your own answer so it's marked as resolved. \$\endgroup\$ – Phil C May 29 '18 at 13:25
  • \$\begingroup\$ it say wait 2 days to accept. \$\endgroup\$ – pra9 May 29 '18 at 13:28
  • \$\begingroup\$ Fair enough. Whenever you get the chance then. Thanks. \$\endgroup\$ – Phil C May 29 '18 at 13:30
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    \$\begingroup\$ "I set the value to zero ohms' And the current crossed the limit of 40mA." That means that it was wired incorrectly. Your wiring diagram shows the full resistance of the pot between +5 and GND and when wired like this the current will be constant and will not change with position of the pot wiper. \$\endgroup\$ – Transistor May 31 '18 at 6:13

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