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I have the following pcb design working based on a previous question. When I plug the circuit all works as expected, the relay does not get energized but when I press the reset button the relay flash very fast 3 or 4 times and gets closed as expected, It works but .. how can I avoid this situation?

My original design was :

enter image description here

I have tried R10 with values 1K, 10K and 47K with same result.

EDIT: Reset schematic

enter image description here

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  • \$\begingroup\$ Check your reset circuitry and button. You may actually be getting multiple resets. \$\endgroup\$ – Trevor_G Jul 6 '17 at 17:19
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    \$\begingroup\$ I don't see any reset button. Edit your question to show where it is. Does the LED flash? What does "relay flashes" mean? Sparks in the relay? \$\endgroup\$ – Transistor Jul 6 '17 at 17:55
  • \$\begingroup\$ Yes, led flash at the same time as the relay open and close 5 times in a few ms \$\endgroup\$ – Marc Jul 6 '17 at 18:55
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    \$\begingroup\$ Try 47 k with a parallel, good-sized cap. I bet the output floats during reset. \$\endgroup\$ – John Birckhead Jul 6 '17 at 19:06
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    \$\begingroup\$ It appears, from your update, that N$14 is driven from a micro-controller - although I can't see N$14 on the main schematic. This means that the problem is in your code which you haven't provided. \$\endgroup\$ – Transistor Jul 6 '17 at 19:09
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I have found the problem, I never mentioned I was using the Arduino Bootloader in my custom PCB, the problem was that I connected the relay to the pin number 13 of the Atmega328, At reset and only on reset the Arduino Bootloader flashes the led conected to pin 13 by design

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