(Please visit the site to view this file)(Please visit the site to view this file)Hello I have read about BJT transistor and i understand better why NPN and PNP now. So I have made some replacement and I have also kept some value too. I am going to explain here what I have changed and how. 1./ First I have modified the led by red one from another manufacturer where the forward voltage seems to be 2V and the forward current 20 mA. the transistor BC807 have VCEsat at -0.7V, I am powering the cicruit with 3.3V and I have decided to use current at 25mA to have some margin security on the LED forward current. my calculation goes then as follow when the transistory is acting like a wire in closed switch 3.3 = - 0.7 +Vres + 2 so Vres = 2 I decided 25mA for current so R should be 80Ohm as per Vres= R * I Let me know if I am wrong 2./ For the relay, which the datasheet is also below, i need to give him 3V to click. at 3V the related curren tis 50mA I power in 3V3 this time I have chosen another transistor PMBT2369 with a 0.25V VCEsat. so my equation goes as follow: 3.3 = 2 +0.25 + Vres Vres = 0.05V so Vres= R x I where I=50ma so R= 1ohm Let me know if I am wrong 3./ I have a problem with my sensor. its voltage is supposed to be 3.3V and I power in 3.3V. I don't know any transistor who got VCEsat = 0 so how to do in this case ? I have use also a PNP here, but I am not sure this is the right things to do 4../ For the limiting resistor in the GPIO I have chosen 1K everywhere considerng that our transistor need 0.7V on VBE to switch and considered the current to be between 2mA and 10mA on the GPIO pins www.nxp.com/.../PMBT2369.pdf ) (Please visit the site to view this file) EDIT: I forgot to add the schematic
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