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Diavolino C6 capacitor

I am using the Diavolino diagrams to help me create my own ATMega prototype special purpose board and I have 0.1 capacitors that have a negative lead.

While studying the Diavolino I am not understanding the purpose of the C6 capacitor and so I therefore am not sure which direction to place the negative lead of the capacitor into the circuit.  I have bought several of the Diavolino kits but the capacitors included with them are not polarized like the ones I am working with so I am a little puzzled here. 

Any help appreciated...

Thank you for the Diavolino. It is a great product and launching point for us beginers.

Sincerely Kurt Jensen


  • Hi Kurt,
    C6 is part of the "auto-reset" circuit along with R1.  This is part of the "RC" circuit that resets the microcontroller to allow programming.   Early generations of the Arduino did not have this, so required you to manually press the reset button to initiate programming.   
  • I knew that it was part of the reset but I was unsure about the current flow direction when a reset occurs.  I need to know which direction to insert my polarized capacitor.

    Does the negative lead connect to the USB connection or does it connect towards the ATMega?
  • This is a good application for an unpolarized capacitor, such as a ceramic cap.  No reason at all to use a polarized type.
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