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This is my first project:

Circuit Image

Do you think that all the pull-up and pull-dwn resistors value are good? Do the capacitor are oversized?

Any suggestions about the circuit in general?

Thank you :)

Updates: enter image description here

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    \$\begingroup\$ They could be. It sort of depends what you expect them to do and how quickly. If something must happen due to pull resistor, how quickly you want and expect it to happen? One thing is missing, a bypass cap for the RTC. \$\endgroup\$ Commented Oct 3, 2024 at 10:24
  • \$\begingroup\$ How is +12 V applied? If switched in, your 500 mA fuse may not be happy with charging up a 1 mF capacitor behind it. \$\endgroup\$ Commented Oct 3, 2024 at 10:41
  • \$\begingroup\$ @Justme I've updated the circuit. Something like this? \$\endgroup\$ Commented Oct 3, 2024 at 10:54
  • \$\begingroup\$ @winny There is an external DC power supply (a MeanWell one). Actually the circuit is designed to work with two different power supply: One pre-optocouplers, and uno post-optocouplers... but it's going to be really easy I'll use just one for everything. \$\endgroup\$ Commented Oct 3, 2024 at 10:56
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    \$\begingroup\$ Good, then should be no issues there. \$\endgroup\$ Commented Oct 3, 2024 at 11:43

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I would not use discrete level shifters. The gates on the inputs can be easily blown, and the outputs seem only to pull down. Do those NFC readers have a bus that's pulled high, like I2C? Even then, just go for a level shifter IC. It can be from the old CD4000 series if you wish - not super fast, but you don't need super fast, I don't think.

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  • \$\begingroup\$ How can be easily blown? Are you referring to the 2n7000 Q8 and Q9 (for example) ? \$\endgroup\$ Commented Oct 4, 2024 at 14:03

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