# Self made microphone burns arduino

I'm very new to electrical engineering and I'm trying to read microphone input with arduino nano. I've made a separate microphone module (based on this example) and plugged it into aruino like this:

Unfortunately it was the last time my arduino was working. It's no longer displayed as a connection, and acts "randomly", so I think my microphone toasts controller for some reason. Here are some more pictures and a scheme of my mic module, could someone explain what am I doing wrong?

simulate this circuit – Schematic created using CircuitLab

R1 - CR1/4W 10 (brown,black,black,gold)

R2 - CR1/4W 2KO (red,black,red,gold)

I have no education in electrical engineering, so I'm not sure about the corectness of this schema of units, just pasted what's written on the pack

• The resistor is 10 Ohm. Not KOhm... If I read the color code correctly. Commented Oct 3, 2016 at 13:50
• Unless I'm completely blind, or you have messed with the colors, that's Brown, Black, Black = 1 0 0 = 10 ohm.
– pipe
Commented Oct 3, 2016 at 13:55
• Huh? I see a resistor brown-black-black. Which is $10\Omega$ Commented Oct 3, 2016 at 13:55
• @Benedictus 10 ohm is not 10 kiloohm. It's off by a factor of one thousand. The schematic clearly shows 10 K. The color code for that would be Brown, Black, Orange. Maybe the other schema needed a 10 ohm resistor.
– pipe
Commented Oct 3, 2016 at 15:30
• When you put wrong components instead of the right ones, it has a good probability to burn something. How can we tell you haven't done anything else not as per "schema"? Commented Oct 3, 2016 at 16:17

I did this a very long time ago, so I might forget something. However, I'm almost completely sure I used resistors in the Kohm range.

After googling a bit I found this post, which might help you get a better understanding of how to use your microhpone.

However, I have noticed you intend to connect your microphone to the analog input of an Arduino. So remember to polarize the analog output to around 2.5V (maybe employing an Operational AMplifier to avoid distortion?) in order to avoid loosing part of your signal (if it is too close to 0V or 5V).

I have checked the circuit you provided. Indeed, it uses 10Kohm and 4.7Kohm to polarize the microphone.

That is, your Arduino gets fried because the 10ohm resistor draws relatively high currents (in the order of 500mA) which Arduino is not designed to handle.

I'm sure that once you replace your resistor your circuit will work fine :) Good luck!

• what resistors should i use?
– Ben
Commented Oct 3, 2016 at 17:39
• @Benedictus You need to use a 10 kΩ resistor for R1 and a 4.7 kΩ resistor for R2. The "k" stands for "times 1000", so they are 10,000 Ω and 4700 Ω respectively. If you're going to be doing a bit of this sort of stuff, you can get bags of a variety of resistors from eBay and the like. They may not be of the highest quality, but if you give them a quick check with a multimeter on its resistance setting to check the value (until you can read resistor colour codes straight off) they will be OK. Commented Oct 3, 2016 at 18:49
• An Arduino should be nominally able to withstand a short to ground or digital supply on any of its output pins, the pin drivers are effectively current sources limited to a couple tens of mA. It'll be overstressing the chip but shouldn't permanently damage it: been there and done that many times. The connections as shown in the question are useless, but shouldn't damage an Arduino as long as it is a model that accepts 5V inputs. Commented Oct 3, 2016 at 19:46
• @kuba thank you, I was not aware that the Arduino board could whithstand shortcuts :) Although now that I think about it, it does make sense, given that it is usually used for training. Commented Oct 3, 2016 at 21:16
• @andresgongora I should add that the "Arduino" part of it is not very relevant, it's a basic property of most CMOS microcontrollers. An Arduino typically doesn't buffer any GPIO signals: Arduino I/O pins are Atmel chip's I/O pins :) Commented Oct 4, 2016 at 13:29