#is this a valid NOT gate that would work in real life?
wintry stump
pearl depot
yes
but that's not the type of transistor typically used in microprocessors
that type of transistor can't be made small enough
(and neither can any type of resistor)
wintry stump
but that's not the type of transistor typically used in microprocessors
oh interesting
how are transistors made for microprocessors?
pearl depot
various methods of creating CMOS logic, or "Complementary Metal-Oxide Semiconductors"
The most common used to be MosFET or "metal oxide semiconductor Field Effect Transistors"
you would have pMOS and nMOS transistors, which differ primarily in the material they are made from, and which have different electrical properties
by putting them together, you can create CMOS logic
formal ether
I'm currently playing around with transistors myself, I'm not sure that layout for a NOT gate would work without some changes to the resistors placements
pearl depot
essentially cmos transistors connect two of their "terminals" (conceptually, they don't really have terminals the way a BPJ transistor does) as if they were a wire, provided that the gate "terminal" has the correct voltage applied
however the "wire" you get from an enabled pmos transistor is really bad at carrying low voltage signals (signals close to 0V) and complementarily the "wire" you get from an enabled nmos transistor is really bad at carrying high voltage signals (close to 5V, usually; depends on the system)
pmos transistors close (form the "wire") when the gate voltage is close to 0V. nmos when it's close to 5V
So the key idea of CMOS logic is to use a network of pmos transistors to "pull up" the value when it should be a high voltage output, and a complementary network of nmos transistors to "pull down" the value when it should be a low voltage output
Thus (unsurprisingly) a NOT gate requires two CMOS transistors. One nmos and one pmos. But it doesn't require any resistors
Nowadays we don't really use MosFETs anymore, because they can't be made small enough (!)
now we use FinFETs, which is a different structure of transistor that mostly shares electrical properties with MosFETs
however the way it is structured lets it use more vertical space and less planar space so you can fit more of them closer together
the name FinFET just comes from the fact that parts of the structure look like fins
formal ether
If you are interested, I'm watching Ben Eater make some simple transistor logic. He keeps it simple and doesn't dump alot of techno babble on you right away.
wintry stump
If you are interested, I'm watching Ben Eater make some simple transistor logic....
This video?
formal ether
yes!
wintry stump
I’m watching it too
I just thought that what I drew out would be a simpler NOT gate
formal ether
I'm practicing with transistors in tinkercad
wintry stump
Why does he put the resistors in those specific spots?
formal ether
so electricty is weird, it likes to flow in the path of least resistance
wintry stump
Right
formal ether
so you have to consider open paths and the resistances in order to "guide" it
it took me a year to finally understand it
somewhat
wintry stump
formal ether
he also didnt label them, but they are different resistor values too
wintry stump
I guess what I’m asking is why didn’t he put the resistor in the 2nd circle instead?
formal ether
the resistor needs to be both before the collector and diode to work
this isnt complete, but its most of the answer
wintry stump
is this a valid NOT gate that would work in real life?
wintry stump
have you used Tinkercad before?
Never, although I think it would prove useful for me to try out
I don’t think this will work but ¯_(ツ)_/¯
formal ether
i could test it, might need some resistors before the transistor bases
doesnt look like it works, only turns off the led when switch B is on
this one works
wintry stump
Why do you need a resistor going into the first transistor but not the second transistor?
And why are there 2 resistors coming out of the 2 buttons both connected to ground?
formal ether
So to answer the first one, the resistor only needs to go into the first one because it effects both transistors once transistor A is turned on. The 2nd transistor (the one coming off the button) prevents to many amps from reaching the base and damaging the transistor, and im not a hundred percent certain why the 3rd resistor helps, but it keeps the transistor from leaking power to the output.
the 1st is 5k ohm, the 2nd is 10k ohm, and the 3rd is 100k ohm resistor
this channel has a few step by steps that really helped me out alot
I am still very deep in the learning phase, so if you find better source that help, lemme know!
wintry stump
Thanks!