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I'm pretty new to electronics, I'm more of a computer guy.

I followed this tutorial to build a vibration sensor. My circuit looks like below.

When I turned it on everything worked, but within a few minutes I noticed a burning smell and my microcontroller stopped working ever since. I suspect I fried the onboard voltage regulator. I tried providing 3.3V to 3.3V pin, now the ESP8266 module is heating up.

I am afraid to use a new microcontroller to fry it again with the same circuit.

What am I doing wrong? I checked for a short circuit, my soldering looks okay. Do I need a resistor to D0 of SW420?

enter image description here

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    \$\begingroup\$ +/- 5V? that means you effectively connected 10V to the 5V input... ya that would do it. Did you measure the input voltage 5V to Gnd at the module? Or is it just an oddly labeled schematic? \$\endgroup\$ – vicatcu Sep 24 '20 at 1:11
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    \$\begingroup\$ maybe something weird happened with the buck converter, since it requires 18 V between the input pins and you supplied only 9 V \$\endgroup\$ – jsotola Sep 24 '20 at 1:25
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    \$\begingroup\$ Did you measure the buck converter output before you connected to the ESP8266 module? It should be 0V (not -5V) and +5V for G and +5 inputs respectively. \$\endgroup\$ – Spehro Pefhany Sep 24 '20 at 2:34
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    \$\begingroup\$ Thank you everyone for your comments. My schema was wrong in my original question, I edited with the correct one here. @ChrisStratton: Yes, my board is not actual ESP8266, it's Wemos D1 mini. I measured the Buck convertor output, the output is 5V to the ground. \$\endgroup\$ – ramesh Sep 24 '20 at 3:30
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    \$\begingroup\$ @tlfong01 please stop cluttering the page with irrelevant comments, this ongoing habit of yours across many questions is quite problematic and needs to stop \$\endgroup\$ – Chris Stratton Sep 24 '20 at 4:07
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Have you configured pin D0 as an input in the software? If D0 is inadvertently set as an output there could be an issue where the SW420 signal is shorted.

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  • \$\begingroup\$ That's unlikely to cause the observed problem. I/O contentions are not good but don't tend to cause lots of heating as I/O drivers are typically fairly weak. \$\endgroup\$ – Chris Stratton Sep 24 '20 at 11:48
  • \$\begingroup\$ What will give if DO is set low as an output and pinned at Vcc by the output of the sensor. Something's going to give. \$\endgroup\$ – mhaselup Sep 24 '20 at 12:01
  • \$\begingroup\$ Losses in the chip output driver will mean the current isn't high enough to cause the described level of heating. Try it on one you don't care about and you'll see. \$\endgroup\$ – Chris Stratton Sep 24 '20 at 12:11
  • \$\begingroup\$ I believe you. It would be seen interesting experiment. \$\endgroup\$ – mhaselup Sep 24 '20 at 12:47
  • \$\begingroup\$ Yes, D0 set to input, there is nothing wrong with the driver. Everything works okay when I provide power via MicroUSB, the board heats up and kills itself if I provide power to 5V pin. \$\endgroup\$ – ramesh Sep 24 '20 at 15:41

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