28-06-2017, 01:28 PM
Just to clarify this "holes" business. Electrons in semiconductors form part of an atom. They orbit a nucleus. I visualised a row of small groups of marbles, each with a nucleus. Imagine only the green marbles are electrons and form a line of the bunches with + one end and - the other end. You can say group A has a central marble with some normal and a green marble placed around in orbit. Next to it group B and C and so on. When voltage is supplied the first green marble of bunch A jumps into the + wire and leaves a hole or empty space in the group. No problem as the green marble in group B hops into the empty space in group A. That leaves a hole in group B so a green marble from group C fills that vacancy. So, the holes move in one direction as the electrons move in the other. The holes don't really exist but they do set up a + polarity opposite to -. Hence bipolar transistors.
The point I ought to make is transition from valve theory to transistors isn't a time consuming step. Based on my own experience to date I recommend:
(1) Learn briefly how electrons jump in atoms and how the holes appear to flow.
(2) Learn about PNP sandwiches or layers. Google potential hills - Owen Bishop explained this in 3 pages.
(3) Beta is pretty much similar to amplification factor in valves.
The holes thing is important to understand and visualisation for me was the only way. If the TV engineers of past years struggled then the use of marbles or bunches of apples and oranges is helpful.
The good news is valve people only really need to tackle the BJT.
The point I ought to make is transition from valve theory to transistors isn't a time consuming step. Based on my own experience to date I recommend:
(1) Learn briefly how electrons jump in atoms and how the holes appear to flow.
(2) Learn about PNP sandwiches or layers. Google potential hills - Owen Bishop explained this in 3 pages.
(3) Beta is pretty much similar to amplification factor in valves.
The holes thing is important to understand and visualisation for me was the only way. If the TV engineers of past years struggled then the use of marbles or bunches of apples and oranges is helpful.
The good news is valve people only really need to tackle the BJT.
