As already explained,the buck converter output @5V will draw < 266mA @5V , which is only 100mA @12V.Either you are not paying attention or you have notdone the math:P= I*V(Ohms Law) Continued ignorance of this is going to get youinto trouble later.All this talk about the buckconverter supprting 2A ispointless because it is only going to draw 100mA @12V. (266mA @5V).How many times do we have to tell you this ?
P= I * V => I = P/V ( devide both sides by V)V cancels on right side leaving P/V = ISwap sides to get I= P/VOHM's LAW !266mA @5V drawn by the arduino is ONLY 190mA@7V coming from the buck converter that is supplying the arduino.You're the one who said you were going to use the buck yo power the arduino because the arduinoheats up too much with a 12V input.PS=>BUCK=>ArduinoGOT IT ?And we've already established that what you plan to use doesn't draw 800mA so why are you using that value. Stick to reality, not fantasy.
You absolutely refuse to learn ohm's law ?You've learned nothing.I give up.How old are you ?
you said 1.5A is not enough
so the current is 1.63A, @ 7V
The solenoid draws 1.2A @12V.Everything you said you planned to use drawsLESS than 333mA @5V which is ONLY 237mA @7Vfrom the buck converter. Your math is all wrong.The buck converter efficiency is probably 95% or better..The power dissipated by the buck converter is the output voltage (7V) times the output current 237mA, (1.65W) , because it based on what youare powering (the devices you listed) snd NOTthe arduino maximum (800mA@5V), so 1.2A@12V=14W + 237mA@7V (1.65W) = 15.65W15.65W/12V= 1.3A (as I stated before).The buck converter current is only 100mA @12V.You don't need 4A@12V because YOURapplication (what you SAID you plan yo useonly draws 100mA (0.10A) @12V.0.1A+1.2A=1.3A@12V, and as Georg has tod us,P=I*Vpower =1.3A *12V =15.65Wcurrent I = P/V =15.65/12V =1.3A (@12V)NOT 4A After everything you STILL Have NOT Googled "Ohm's Law".Instead you choose to consult the vendor.
I did studied ohm's law, just the basic and the formulas.
This is Reply #37 .There is not a single reply from you where you have demonstrated (or even posted calculations) , thatyou have learned anything about Ohm's Law.Not one equation.Not one formulatNot one Ohm's Law calculation.If you studied it , then you learned nothing and you need to review it.Prove that you know the basics.Post a reply that contains Ohm's Law calculations and explain what they mean.Talk is cheap.If you had replied: "You know what ? You're right.I still don't get it."then I would be posting this reply.But you said you "studied" it.What exactly is you're definition of "study" ifit does nit include understanding ?Nothing you have said indicates even the remotestlevel of understanding of Ohm's Law.Is it so important that I need to hammer away at itagain and again ? Some would say yes.